Questions turned in during previous semesters, sorted by category.
The categories are:
  1. Solar System Exploration and Space Travel
  2. Planets (including the Earth) orbiting the Sun and planets orbiting other stars
  3. Stars
  4. Life and Search for Life
  5. Black holes and other strange objects or concepts
  6. Galaxies
  7. Cosmology
The easiest way to find answers to questions you may have is to search within this file on the main topic of your question, using the text search feature of the web browser that you are using to see this page (e.g. under the "edit" menu within the mozilla browser).


Solar System Exploration and Space Travel
Do we photograph mostly from satellites? [Yes, but also from telescopes on the ground]
What is the temperature on the moon when the US landed there? [The moon has no atmosphere to speak of, and as a result the temperature differences between day and night side are enormous, from +257F day (hotter than boiling water on earth) to -283F night side. You may want to look up the exact landing sites of the astronauts (they were on the day side) to find the exact temperatures].
Is it possible to use a gas or diesel engine in space, considering the lack of oxygen? For example a space rover, how is it powered? [As long as you bring the oxygen along to burn the diesel or gas. Space rovers are powered by electricity, generated by voltaic cells on their solar panels.]
 What is the size of Jupiter's moon Europa compared to Earth? [Look it up!]
Are the rovers on Mars still being used to this day? [Yes! In 4 years Spirit has traveled about 4.5 miles, Opportunity has gone about 7 miles, and they are both still going strong. However, winter is approaching and so the rovers will find a “winter perch”, a safe place to wait until the Sun gets high enough in the sky for the rovers to be able to generate more electricity. They are still exploring and taking data, and will continue to do so until their batteries wear down and lose the ability to be recharged.]
How much does it cost to send a craft to space? [About $500M to $1.3B per shuttle launch, depending on who you ask. The cost comes to $10,000 per pound. This includes the entire cost of the program, not just the actual launch. The "space tourists" flying on the Soyuz to the space station paid about $100,000/lbs of body weight. Presumably it can be done cheaper....Even the "space tourists" flying from New Mexico, if it ever comes to pass, will be charged $200,000 for a 10 minute flight. That comes to $2,000 per pound of useful cargo. The rest that goes up is only there to bring the tourists up, so this is the actual cost. And the craft does not go into orbit so it seems a lot cheaper than $20,000 but you definitely get less in return compared to orbiting on the space station. If you consider the cost of unmanned robotic missions and the success and life times of those missions, the cost are far more reasonable because you get a long-lasting instrument in space. ]
Is the E2 mission to Europa, scheduled for launch in 2008 still on? [No, but a mission to Europa has been selected for further study.]
If Mars had ozone like earth, would it receive enough light from the Sun to heat up Mars to a habitable temperature? Is Mars in the habitable zone? [Mars differs from Earth: 1.5AU away, on average, so factor 2.25 less sun light, much more elliptical orbit; seasons on mars are to some extent affected by being closer to sun in N. hemisphere winter, less atmosphere, avg temp = -50C, hottest day time temp. I have seen published is 27C at equator. That won't last long, so question is how much more atmosphere you need to trap that heat. I don't know that. Perhaps the terraforming link will give some speculative answers. Note that Mars did seem to have liquid water in the past, so it had a much denser atmosphere at some point.]
Is it possible to use reactive elements to travel? [We use radio active elements to power the instruments on small space craft that travel too far from the sun to use solar power. We have not used radio-active elements to power the
thrusters on rockets. That likely would take more power than we would find comfortable risking launching, plus it is likely heavy equipment.]
What does "space" consist of? Nothing? Gases? Dust particles? [All of the above, in a way. A real "vacuum" is probably not present anywhere, there is always some stuff. However, the density of matter in interstellar space is so low that we can almost call it a vacuum.]
How far is a light year? [Light moves at 300,000 km/s so multiply that with the number of seconds in a year.]
How many times have we visited the Moon? [I think the first manned landing was in the Apollo 11 mission, Apollo 13 was the infamous failure, and the last one may have been 17. So, 5 or 6 times.]
 With the debris flying around in space, is it at all dangerous to launch satellites or plant satellites in space? [Yes, it can be. So far very few collisions have happened, but even something as small as a bolt could be dangerous because of the high collision speeds. Most of the junk in orbit around Earth will stay there for very long times and not fall back to Earth. It just keeps orbiting.]
 How far in the sky do you have to be in order to float rather than falling back to Earth? [The force of gravity between two objects decreases as the square of the distance between them. This is pretty fast decrease. E.g. if you move away from the surface of the Earth, which is about 4500 miles from Earth's center, to a distance of 45000 miles (10 times further), the force of gravity is 100 times weaker. Still, in principle, gravity never really goes completely to zero. The homework addresses the issue of weightlessness, free-fall, and gravity in more detail.]
 Is it possible to create zero gravity on Earth? [Yes, when you are in free-fall or e.g. when you float under water.]
Why isn't the Hubble telescope in higher orbit? Couldn't we see more at higher altitude? [Because it couldn't be launched into higher orbit or serviced by astronauts in higher orbit. It was a decision that was made at the time that they wanted to be able to visit it to upgrade and fix instruments. That limited the orbit to where  the shuttle can reach it, which is a low-earth orbit.]
 Is the vacuum of space itself heated by the sun? The space near it at least? [We can only measure or even define a temperature as a measure of the motion of particles. So, if there a vacuum, it is hard to define a temperature. However, radiation does have energy, so if light is passing through space we can define the "energy density of radiation" which is the amount of energy contained at any given moment per unit volume in space.]
Has anyone ever attempted to go to space on their own (without NASA)? [Well, the Russians have without NASA....Commercial space flight is only beginning to be developed now, and it will take a long time before we see many people traveling large distances in space commercially.]
Why haven't we gone to the moon again? [Lack of money and allocation of resources to other space science/engineering activities. Also, in inflation corrected dollars, the NASA budget is less now than it was in the 60's and 70's.]
 If a ship was able to travel at the speed of light, the danger of hitting things is apparent. With that in mind, would there need to be an invisible force field around the ship being emitted faster than the speed of light to deflect objects? [We could ask the same question for a ship travelling near the speed of light, since that is also very fast, and then we wouldn't need to break the universal speed limit. Even so, remember that space is pretty empty, so the odds of you hitting anything is pretty small.]
What effects would the human body have being in space the amount of time it would take to go to Mars and back? [Well, being weightless affects many bodily functions and things like muscle mass. One of the most important is the fluid balance and flow in the body which is designed for a system with gravity. You should google space travel and find the longest time an astronaut has been in space and in what condition he came back. Mars is not too far to survive the trip but if you want the astronauts to be in top shape when they get there, they will need the ability to exercise on the trip.]
How long does it take to get to the moon/mars? [To the moon about a couple of days, to mars 2-6 months, depending on where we are, where Mars is, and which trajectory is chosen.]
During a satellites' flyby, why don't we have them "drop-off" other observatory instrumentsin the planet's orbit or surface? [During a fly-by this is not easy because anything you "drop off" has the same speed as your space craft and hence will continue to follow the "flyby" path. We have "dropped" things from orbiting satellites, e.g. the moon landers, and small space craft that went into Jupiter's atmosphere one into Titan's atmosphere (Saturn's largest moon).
Can asteroid families become planets? [Unlikely since they won't get close enough to merge into a larger object. They tend to drift farther apart over time due to small changes in their orbits from encounters and resonances with the larger planets.]
How come moons are not considered a planet? Maybe they are just closer to each other? [Think of a moon as a natural object that orbits a planet, and a planet as one that orbits the sun. The planet is is the bigger of the two. Other than that, the nomenclature is indeed rather arbitrary, e.g. Pluto and Charon are not that different in size so almost a double (dwarf) planet system.]
Astronauts: how much do they earn? Can they get life insurance? What benefits to they get, knowing their job is risky and they may not return from a mission? How many candidates are up each time for space travel on a shuttle?
NASA's astronaut program info
With increasing cost of fuel and lack of evidence why does NASA keep spending more money? [Fuel cost are completely insignificant on the scale of the US economy and fuel consumption. Also, what do you mean with "lack of evidence"? We have barely started to look, have not analyzed samples on Mars in detail, etc. Remember, the search for life is not the only or even main driver for what NASA does. The main (scientific) driver is to learn more about our place in the universe and the origin of the solar system; life is but one aspect of that larger quest.]
If a craft goes to slow while traveling in space, what will happen? Would they just float there? [Their velocity would slowly approach zero with respect to the body they left from; if there were another object in the neighborhood, its gravity could attract the space craft and speed it up again.]
Is it possible to get lost in space? Or get stuck in the orbit of a planet? [Not sure what you mean with lost in space. You can certainly wind up going in a non-meaningful direction if e.g. the craft were to run out of the compressed gas it has on board to change its direction. You could also get stuck in an orbit of a massive object but presumably you would have calculated long in advance your approach speed, its mass, and what the consequences would be of any manoever you make. ]
If aging is based on the force of gravity on your body, and you know the force of gravity, couldn't you calculate how much the process would be slower or faster than it is here on Earth, and then apply that to space travel at speeds close to the speed of light to calculate how much "time" would have passed on Earth when (if) you return?
[The problem is that aging is not only caused by gravity. Most aging may well be due to chemical changes in the body, the accumulation of "free radicals" in the body, etc, so aging would happen too if no gravity were present.]
Would it be possible to take a small piece of radioactive material and use it to power a car for more than a lifetime? [I don't think so, but it depends on how much radio-active material. The sources on a space craft are just "passive" energy generators, that is the energy comes from the radio-active decay. It is not a nuclear power plant with a controlled fission reaction going on. The passive decay is probably too little energy to power a car.]
 In your opinion, do you think the space port is a positive thing? Couldn't we do other space exploration with that money because in a way this seems like it is just an opportunity to capitalize on an untapped resource. I guess what I am getting at is that I don't understand why that money wouldn't be put towards furthering a mission to mars. [I have my strong doubts, because it has often been claimed that going into space will become cheaper, but it has not been proven that this can be done. Space ports are largely driven by private funds, or state funding in the present case; that money would not have been allocated for a mission to mars I suspect.]
The book states that it takes 4.4 years to send a message in the universe and 4.4 years for a response, so about 8 years. How accurate is this system of communication? [Slow. And the signals would be very very faint.]

Planets (including Earth) orbiting around the Sun and planets orbiting around other stars
Do planets/stars ever collide? [Planets probably did in the past when the solar system was forming, e.g. origin Earth-Moon system could be due to planet collision. Not likely any more now that planets are on stable orbits].
What do the rings that surround Neptune, Jupiter, Saturn, consist of? [small pieces of rocky, dusty, and ice material]
Why do we orbit the sun rather than other stars in space? [The planets in our solar system were formed together with the Sun; other stars are too distant to "steal us" away through their gravity.]
 What is the difference between an asteroid and a meteor? [A "meteor" is a "shooting star" or a "falling star". Not a star really, but a usually tiny piece of material falling into the Earth's atmosphere. The material could be left over stuff from a comet ("comet dust") or a small piece of rocky material that could be part of the general meteoroid and asteroid population. A meteoroid can be thought of as a small asteroid.]
Why does  the moon appear to be a different color on different days? [The light of the moon is just reflected sun light. The changes in the light of the color from the moon and the sun are determined by the local conditions of the atmosphere; e.g. is there smoke in the atmosphere? Ice crystals? Water droplets? Little or a lot of water vapor? Pollution? etc.]
 Why does the moon appear reddish during a lunar eclipse? [Because the sun light refracts through the Earth's atmosphere and the red light of the sun set will illuminate the moon even at the moment of totality.]
How frequent do lunar eclipses occur? [About twic a year].
When is the next eclipse? [see link below.]
When is the next total solar eclipse? [see link below.]
Here you can find all about future eclipses (including a total lunar eclipse Feb 20, 7-9 pm MST)
 Is sun set and sun rise always going to be red? [No, this depends on the clarity of the atmosphere. If it is very dusty or wet it will turn red early, if it is very dry and clear, the sun will set like a yellow ball.]
 Did the Greeks know what causes a lunar eclipse? [They sure did.]
What is it called when the sun covers the moon? [Impossible...]
When there is a ring around a full moon, does that mean it can only be ice cristals, or can it also be a perfect deflection off the full moon? [Color effects around the moon are always the result of the Earth's atmosphere and its interaction with the light coming from the moon.]
 Did the Greeks know the natural orbit of the planets? [No, they assumed they were circles. They did not discover that they were ellipses.]
Could Kepler explain why an object fell back to earth when dropped? [Kepler did not discover the existence of a force of gravity, Newton did. So, no he probably did not have a good explanation for this.]
Could earth ever move far away from the sun? [Yes, .e.g. if and when the sun loses some of its mass, the force of gravity will decrease and the Earth's orbit will change.]
What are the chances of all 9 planets lining up linear with the sun? Could this cause any problems? [Small, and even if it does happen, it will not cause any problems.]
Are the orbits of the planets more or less on the same axis? [Yes, more or less. Pluto's orbit goes most out of the ecliptic plane.]
Since the sun is a lot larger than earth, is it possible the large mass of the sun could pull earth into it due to the large gravitational pull? [No, the earth doesn't fall into the sun because it is "orbiting" the sun; it doesn't just fall towards the sun it also moves perpendicular to that direction and it is the combined movement that keeps it circling the sun.]
How do jovian planets stick together as a whole if they are composed of gases? What keeps them from spreading into the rest of the solar system? [A gas can be kept together by gravity just as ordinary matter can. As long as the gravity is big enough to balance the pressure of the gas, the gas cannot escape. Another example of that is why the earth can retain its atmosphere; the gravity keeps the gas bound in a thin layer around the earth's surface.]
How do we determine the age of a planet? [From age dating rocks if we have them. Difficult to do without actual samples.]
 How can you scientifically prove the ages of objects in space, like planets, solar systems, galaxies, the universe, etc? [Universe: by tracing back the rate of expansion in time. Planets: age dating rocks, stars: by knowing how stars evolve over time and from their abundance of elements heavier than H and He. It is not easy by the way to get accurate estimates for any one star (except Sun which we can study in great detail), but we can very good ages for groups of stars formed together called "star clusters".]
How do planets form? [See section in book on the "solar nebula hypothesis].
Can stars "steal" planets? [Not likely, mostly distances between stars are too big.]
With all the pressure and gravity holding and keeping planets together through gaseous states, it is possible for the pressure to transform the shape of a planet? [Shape is determined by gravity, pressure, rotation rate, and structure. E.g. rocks can be very non-spherical in shape, but when they get very big (more than hundreds of miles across) gravity will win and make the object look spherical. Planets made from gasses will always be mostly spherical since gas can be compressed easily. Rotation of a planet tends to flatten its shape. Earth is somewhat oblate, not totally spherical.]
 Is it possible for erosion or an earthquake to open up the earth below the crust to the mantle or core? [One can argue that this is what is happening at the intersections of the major plates on earth, especially those locations where we see the liquid rock (magma) flowing out, like in some places in Hawaii or in volcanoes in general. In general though, the crust is quite thick and not easily "broken open" to expose the Earth's interior.]
Through convection or conduction is it possible for the Earth to get to the point of being so hot that it explodes (not like a volcano)? [No, because the Earth is essentially cooling down and so there would have to a source to additional energy to heat the interior much more than it is now. There is continuing decay of radioactive materials which contributes to the earth's interior temperature, but as elements decay, the rate of the decay will also go down, not up.]
Scientists say that if the earth increases 6 degrees C that the earth will be in danger, is it true only this small increase in temperature to create such big problems? [Think about why we are concerned about even seemingly small temperature changes in the context of HW 2 on global warming.]
Does what happens to the Earth's environment (i.e. pollution/global warming) affect other things in the solar system? [Not really, the Earth in a way is a rather "closed off" system. The only exceptions are the sun light (and the bit of light from other objects) that comes in from outside and the collision with other objects, usually small ones causing shooting star but occasionally very big ones, plus also continuing collisions with charged particles ("cosmic rays"). But we don't put stuff out from Earth into space so in that sense what we do on Earth does not affect Earth's environment much.]
What is the closest plate to where we are now? [The entire Earth is covered by separate plates, and we are on the North American plate. Note that the plate edges extent beyond the landmasses and often fall in oceans.]
How many layers does earth have? [Four. Look them up!]
Does mars have layers like earth does? [I would think so, though the details will vary.]
Would, given time, our Jovian planets become terrestrial? [Not likely, given their different composition. However, it is an interesting question to speculate what Jupiter might look like once its interior has cooled much more and how it might change.]
Do gas planets have any kind of solid middle with a more tangible texture? [Often there is a solid "core", and the layer above that can behave like a "metal" even if it is made from mostly hydrogen gas. The interior structure of planets is very complex due to the many physical and chemical changes that can happen (the "equation of state" is very complex). Stars by comparison are much simpler in that throughout most of the star the gases behave as "ideal gases" which obey simple physical laws.]
If a planet is pure gas then couldn't it be possible to send something through the planet? [No, the amount of gas or "air" is sufficient to cause enormous friction so a bullet or rocket etc would not pass through such a planet.]
Why is Venus' rotation slower than Earth? [Good question! Let me know when you find out :)]
Is Saturn the only planet with rings? [No, all gas giants have rings, though Saturn by far the most spectacular.]
Are molecules around planets gathered/grouped by the pull? [Yes, gravity and temperature and pressure decide if a gas can remain pulled to a planet or not. E.g. if you make the atmosphere very hot, the gas molecules could gain enough speed to escape from the gravitational field. Or if you make the planet too small, the gravity could be too low to retain an atmosphere (think moon or mercury).]
To prevent global warming, would you suggest that we quit burning carbon, fossil fuels, etc, alltogether? [This would hardly be a realistic solution at this time. However, reducing the burning of fossil fuels is a good first step given that we don't know how drastic the effects of ever increasing greenhouse gases will be, or how soon climates may change so drastically that we don't have time to adjust as a world population.]
How can the ocean regulate or thermostat by regulating carbon dioxide content, without pulluting or harming ocean life? [(Read about the CO2 cycle in the book (pages 134-136). Some numbers: Oceans have 60 times as much CO2 "locked up" as is present in the atmosphere. Rocks on earth have 170,000 times as much CO2. ) We still worry about the atmospheric content because that is what helps set the temperatures. Also, the natural regulation mechanisms the Earth has all work on very long time scales and it is unlikely they would help address the rapid increases that we are now causing in the greenhouse gas content.]
If all the gas planets have rings, would it be an assumption then that all gas planets everywhere have them? [That could be, although a hot Jupiter right next to star may not not have ring system.]
Could a terrestrial planet have rings? [I suspect so, although our Earth might be difficult given we have that big moon there and I don't know a ring system would be stable. If I put particles in a ring system around a terrestrial planet with no big moon, they probably could persist for  a long time. The reason terrestrial planets don't have ring systems is likely our place of formation in the solar system (close in, where it was hot), and the small mass so that we did not attract a lot of junk to stay in orbit around us.]
 Why can't people just learn to adapt to warmer temperatures/global warming; we are doing it now? [We can to some extent, but there are many issues. Even small temperature changes can bring about changes in ocean levels putting certain countries at risk of flooding. Climate change also affects agriculture and the ability to grow certain produce in certain areas. These changes, if they happen quickly, could result in global political unrest and destabilization. Another issue: we have no idea when or even if the increase in temperature will stop. The endpoint is not defined, there may be reasonable predictions for it, but no certainty. Essentially, the increase in CO2 and other gases in the atmosphere we are seeing now and the increasing temperature is one big experiment where we don't know the outcome.]
 Are ice caps on Mars melting, growing, or staying constant? What could change this? [ The Martian ice caps (carbon dioxide + water ice) have been seen to grow and shrink with the seasons. This points to changing temperatures during the course of the Martian year. Since there isn't much of an atmosphere to hold in the heat, there are large temperature variations throughout the year.]
Why is Venus the only planet that rotates clockwise?  [Theories of solar system formation predict that all planets should orbit in the same direction. Uranus, however, rotates on its side and Venus rotates “backwards”. One theory for this is that these planets were hit by some massive object sometime in the past, causing Uranus to “fall over” and Venus to either lose rotational energy or “flip over” so that it essentially is rotating backwards.]
What is believed to be the reason for the existence of the asteroid belt? [The asteroids in the belt are probably left over material from the formation of the solar system that was not able to form a planet. For comparison, think of Saturn's rings, which are formed of chunks of rock and ice that are unable to come together to form a moon.]
What specific chemicals/gasses make up our atmosphere which block out most harmful UV rays? [Ozone (O3) is best known and most important element to block out the most harmful UV but many other molecules also have transitions in the UV which help absorp UV.]
How do holes in the ozone layer affect space travel? [No effect.]
How did scientists discover Pluto? Isn't it too cold to go out there? Does the same diameter's angle system work as well for planets? [Clyde Tombaugh, the founder of the NMSU Astronomy Dept, discovered Pluto in 1930 as a young man working for Lowell Observatory. He found it by looking for slowly moving objects across the sky in the direction opposite the sun. (Slowly moving, because they knew another planet had to be far away, hence it would appear to move very slowly. Yes, it is cold out there, the first unmanned mission is on its way to arrive in 2015 or so. Yes, small angle formula works for anything: if you can measure its angular size and know its distance you can find its diameter.]
How does the magnetic field affect the earth compared to other planets? If there were no magnetic field surrounding the Earth, how would we be affected by the solar flares and winds from the Sun? [The Earth's magnetic field is much stronger than some other planets (Venus, Mars) though not as impressive as, say, Jupiter's. The magnetic field lines act to "trap" charged particles from the sun and lower energy cosmic ray particles from space. This is probably a good thing; while plenty of cosmic rays make it through, the rate is much higher in space and so we are shielded by the magnetic field and atmosphere to some extent. It is hard to speculate if life could develop without a strong magnetic field though it probably hasn't hurt.]
Did the location of the moon affect earth's development? [The moon causes tides and there is some speculation that tidal pools might be good places for life to have developed. A very important thing the moon does is to stabilize the Earth's rotation axis (the "tilt"). This provides far more stable climates than if it were allowed to wobble more; some estimates say it could change drastically on short enough time scales that life might never have enough time to develop to advanced species. Apparently Mars's axis has wandered a lot more. I
How come the earth has gravity but the moon doesn't? [Oh, but it does! The moon has less gravity on its surface than Earth, because it is smaller and less massive. If you take Newton's law of gravity and calculate the ratio of the forces of gravity on the same object when it is on the moon versus on the earth, you find a ratio of 1 in 6. So the force of gravity when standing on the lunar surface is 6 times weaker than when standing on earth.]
Where is the hole in the ozone layer located?
southern hemisphere ozone hole in 2006
Northern hemisphere ozone hole in 2000

If the Earth's rotation was somehow altered, would this change the pattern of ozone depletion? Why is the hole in the ozone where it is? (where no people are?) Information about the ozone hole and ozone depletion
Is terraforming an actual scientific process that can be done or is it just a theory? [At this point, speculation, less than a theory.]
Could you explain the process of a jovian planet turning into a terrestrial planet in terms of physics. [No. But a massive planet expert could tell you what happens over very long times when Jupiter continues to cool down and if it were ever to "solidify" anywhere as it gets colder and colder.]
I saw on the news that astronomers have recently found a new solar system in our galaxy. What does this mean for our solar system? [Nothing concrete, but it is interesting that we keep finding more stars with planets.]
 Instead of a search for life, why isn't there a greater search for habitable zones in the solar systems? [There is, in fact we can fairly well estimate for each star where its habitable zone might be, because this mostly depends on the star's luminosity and heat (color); the trick is to find planets within that zone.]
What is stopping us from seeing earth-sized planets? The size of the telescopes? Location? [Earth'sized planets are too small to be seen easily, and of too low mass to cause significant "wobble" of their star. We will be able to detect them as techniques and instruments improve.]
Can a solar system have more than one star? [Yes, although I am not sure it would have very stable orbits for the planets; it depends on how far that second star is. If it is much further away than the planets are to one star, the system could be stable. If the two stars are close, the planets will have very complex and possibly continuously changing orbits. The "three-body problem" in Newtonian gravity has no exact analytical solution.]
For planets orbiting distant stars, does wobble tell us size and/or distance from their star? Or does it only show the presence of a planet? [All, if we have good enough data. The orbital period of the planet immediately follows from the data. The mass of the star may be known from other ways, e.g. by seeing that type of star it is from its spectrum. With period and stellar mass known, we get the limit on the planet's mass.]
Wasn't there a recently discovered planet found orbiting a brown dwarf that scientists believe is in a "habitable" zone that they are even calling "earthlike"? [Discoveries such as that one are announced regularly these years. Expect to hear about more.]

Stars
What is the average life of a star? [This depends on the mass of the star. We will discuss this in the course,]
How hot is a star versus a planet? [Stars are hot because they are massive and because they generate energy in their centers. Planets mostly reflect star light and have some internal heat from cooling and radioactive decay. Typically, planets are about 50K-hundreds of K in temperature, whereas stars are thousands to tens of thousands degrees Kelvin. "Hot Jupiters" found near other stars can also be 1000K or more].
 What constitutes a star? [A star is hot sphere of gas. The typical star consists of about 71% hydrogen gas, 26% helium gas. The remaining 2% is made up by all the different elements in the periodic table.]
 Are gases around the corona really purple? [Yes, hydrogen gas emits red, green, and blue emission lines that together can combine to a purplish color.]
If the nearest star is 4 light years away can we be sure it will be there when we arrive? [Yes, we can be. Stars change only very slowly and we would know enough about this one before heading there that it would not disappear.]
 Are there any unexplained lines in the color spectrum of the sun? I.e. chemical compounds that we don't know about? [None that I know of. Historically, lines were identified in the sun that were not known on earth: the element helium (helios=sun) is named after the sun.]
Are there any other alternatives to nuclear fission and fusion in regards to high amount of energy? What happens when these resources are depleted (nuclear fission/fusion)? [Fission resources are likely to be depleted before fusion, because there is a lot more hydrogen (in water e.g.) than uranium or plutonium. The largest source of energy is probably solar; if we can tap into that effectively, we have a supply for a long time. I read somewhere that  the energy that the Sun emits is so much that if we could collect it all, one hour of sunshine collected over the entire US would be enough to supply all the US energy for a year. Of course, that does not include any considerations about how to store it, what form that energy takes, can you fly airplanes with it, etc. but still...]
You mentioned that in order to make a nuclear fission chain reaction, the elements like uranium must be refined enough in order to create the desired result (a big bomb!). How do they determine the amount that it needs to be refined without making it explode? [This is calculated from knowing nuclear physics and cross-sections for interactions between nuclei and knowledge of the exact reaction rates etc.]
Can planets become stars? [No, they have insufficient mass to start fusing elements in their core to generate energy.]
Do stars ever stop being created half way through? Run out of energy? [The amount of energy that goes into creating a star depends mostly on the amount of mass available. If there is not enough mass to begin and sustain hydrogen fusion, the object becomes a brown dwarf (sometimes called a “failed star”). A brown dwarf will initially glow because it's hot (maybe even hot enough to burn deuterium or lithium for a little while) and will cool over time until it goes cold and dark.]
Can solar wind blow particulars into space, enough to overtake the gravitational force? [The solar wind does spew particles into space, which escape the Sun. When these particles get to a planet, if there is a magnetic field (like at the Earth), the magnetic field can deflect the particles and help shield us from the solar wind particles. We see evidence of the solar wind in the aurora, observed mass ejections from the Sun, and even by collecting the particles (Stardust mission)]
What is the difference between a star cluster and a constellation? [A constellation is a chance superposition of stars on the sky that may look like some systematic pattern. We define 88 constellations to cover the entire sky. The stars in each constellation are not physically connected and may be at very different distances from us. We basically use the constellations to indicate locations in the sky so we can find objects. A star cluster is a gravitationally bound group of stars that all formed together and so all stars in a particular cluster have the same age and are at the same distance from us.]
What is the best way to find constellations and when is the best time to do this? [Any time of the year, since the entire sky is divided into constellations. The easiest to find are: Orion (fall, winter, spring), Big Dipper and Cassiopeia (more or less year-round), Pegasus in the north, Lyra, etc.]
What causes stars to form together? [A gas cloud that collapses to form stars is usually so big that not one star can form but many, of different masses.]
Are stars brighter than planets if they are located at the same distance from earth? [Stars are millions to billions times brighter than planets. Planets, in the visible, only reflect the star's light, so they are much fainter.]
I saw on the discovery channel that there is a star made of carbon forming a star sized diamond. How is this possible? What is it fusing if its not hydrogen or is it dormant? [This is a stellar remnant, the core of a star that has stopped fusing elements. The sun may end up like this; it will fuse He into Carbon in the core, then it can't go further with fusion (too low mass, hence gravity) and so the carbon core will remain. The central part of this carbon star may be cristallized carbon, hence "like diamond". One example was named "Lucy".]
What can we learn by studying binary systems? [Stellar masses, sizes, orbits, frequency of binary formation, etc.]
What is the potential for how long stars can shine? [The mass of a star tells us how much hydrogen gas it has to potentially turn into Helium as an energy source. The amount of light a star emits per second tells us how fast it uses up that energy. The ratio of the two numbers is proportional to how long the star can shine.]
How is it possible to measure the amount of heat from stars billions of miles away? What type of instrument is used other than a telescope? [A telescope is all that is needed; heat from stars comes to us as light so if we measure all the light the stars emit, we know their energy output.]
Our star is far away form any others. How far are the closest stars from one another (that we have seen)? [This depends much on environment. Stars are closer together in the centers of star clusters and the centers of galaxies. Stars are also closer together in binary systems; in the extreme case, orbital periods can be short as days or even hours.]
How do you know if a star is going to become a white dwarf or a supernova? [That depends on the mass the star has when it is formed. Only massive stars (more than about 8 solar masses) will become supernovae, the others white dwarfs. In binary star systems, the situation is more complex.]
What kind of star is required to have a supernova? [See above.]
If the star "beatle juice" (Betelgeuse) is bigger than the sun, why are we worried about the sun losing energy? [Because we are not anywhere near Betelgeuse. Just as well, it may well blow up as a supernova soon.]
When the sun dies, will any life exist on earth or would the graduate change of the sun eliminate all life in the process? [I think the odds are good that life would disappear well before the sun becomes a planetary nebula, since it will become so large before this happen that its brightness will go up by factors of 100-1000.]
 Is the Sun supposed to turn into a planetary nebula and why? [Yes. When it runs out of energy, the sun's core will compress and start fusing He into Carbon. As this happens the outer layers swell up. At some point, even that energy source runs out and the star becomes unstable. It will eject its outer layers, while the remaining mass (about 60%) will contract to a white dwarf, which is the only stable configuration that can withstand gravity at that point.]
 Are all stars the same temperature? [No. There is a range of about 2000K to 50,000K]

Life and Search for life
How do we know life needs water or oxygen to live? Couldn't other organisms adapt to their environment? [Not all live requires oxygen or water, so we do look for other life forms, but it is plausible that advanced life forms may need oxygen and water. Also, it makes sense to look for water and oxygen as signatures of possible live. It doesn't exclude other possibilities, but you might as well first look for what you know best. Molecular oxygen (O2) would not exist freely without a source (photo synthesis in plants) because it reacts easily and would disappear from the atmosphere.]
Why don't we take life from Earth to another planet and see if it can survive? [Because we would forever lose the possibility to determine if life was there without us bringing it, and what form that live might have.]
What will humans evolve to in the future? [We can't know. We can at best speculate on short term changes, and as we continue to study the DNA of future generations in ever more detail we may be able to see some patterns emerging that might lead to better predictions. But as long as we don't mess with it (through genetic engineering) the changes are unpredictable for the long term.]
Are there other theories describing evolution? [Wallace had similar ideas to Darwin. However, there really was not a "competing scientific theory" that Darwin de-throned. His work filled a scientific vacuum. Subsequently, there has been much work on the finer points of evolution, its time scales, whether evolution will always lead to certain traits ("convergent evolution") etc, but within the scientific community the basic framework is not doubted. Note that "intelligen design" is not a scientific theory, as much as its proponents would like to argue that it is.]
Are there any other theories aside from Natural Selection and Darwin's ideas? [see above]
Do you think that humans will ever be able to do selective breeding only passing on strong traits or being able to choose traits? [We are already doing that. Every domesticated animal is selectively bred. So are most if not all farm animals.]
How do viruses evolve so they have different shots each year? [Through natural selection! Mutations in the replication of the viruses happen and those that happen to be get a change that makes them resistant to the anti-bodies we already have from the shot, will survive.]
The book states that the "materials in living organisms always exhibit some type of order". Is the just our broad assumption that life always develops in orderly manner because we prefer to use order in our lives? [Natural selection can lead to order simply because better designed systems may have advantages over less well designed systems. It is not a necessity of natural selection that this happens, but it may happen (as it has when we think about advanced species). Clearly, people have become very successful at surviving because of our high level of complexity which has led to defenses against disease, famine, and control over other life forms, etc. That same complexity though could become a problem, e.g. in a dramatic climate change we might not be very well adapted anymore to survival. Or our increased biological complexity might also open the door to many more viruses than could affect a simple organism.]
What might cause a mutation in the copying of DNA? [Look at how the DNA is replicated during cell division. It uncoils and picks up copies of (sections of) amino acids that in principle should give two copies of the original but one can easily picture that the match is not exact.]
Could we create a new like species? Breed it to be able to tolerate different living conditions? [Yes, in some senses we have, e.g. dogs with thick pelts that can survive cold climates. One could argue that new species have been made by mixing DNA in genetic experiments. Remember that the division between species is based mostly on traits and appearance, so sometimes there is a lot of debate as to whether e.g. one particular kind of bird is a separate species or part of an existing etc.]
Do all life forms on earth depend on oxygen? [No, we have anaerobic life forms in extreme environments. Look up "extremophiles" in your book and on the web and find some of them. Oxygen has certainly been advantageous in developing complex species it seems.]
 Do current scientists believe that life can be on Venus but adapted to its harsh environment? Is there an interest in investigating Venus in the future?  Is it possible for extremophiles such as certain species of archaea to survive on Venus?
 [The conditions on Venus are so extreme that probably very few scientists think any sort of life could thrive there. The temperature is hot enough to melt lead, the pressure is the same as if one were 1000 meters below the ocean surface, there are no liquids of any kind, and the magnetic field is too weak to protect the planet from high energy cosmic rays. This kind of environment is too extreme even for extremophiles as we know them. Venus is still being studied by many planetary astronomers (to try to better understand its atmosphere and formation for example) but not in the sense that we are expecting to find evidence of life there.]
Are there any theories that suggest that life was delivered to Earth via a comet or asteroid? [No theories, I would sooner call them hypothesis or even educated guesses. We don't know enough about comets, the early solar system and the earth's own history to prove this either way at this point. Life is unlikely, but complex organic molecules are found on comets and in certain metoroids.]
Based on the molecules we find on comets, how will we know where they came from and if those molecules exist elsewhere in our solar system/galaxy? [The comets orbiting the sun formed with the solar system at the same time as Earth. They haven't run into many other stars, although certainly they exist in "interstellar space" somewhat and whatever clouds of gas they move through with the solar system may leave dust particles and molecules on their surface. So it is probably likely that the composition of our outer solar system is much like that elsewhere in the sun's neighborhood of the milky way.]
In the case that global warming worsens exponentially and Earth turns into Venus, has research been done to see if we could become totally self-sustained? E.g. living on the moon/mars or on a space station. [We don't need to do research to answer this question with no. Even the biodome in Arizona failed to be self-sustaining. Imagine now a much more primitive base on the moon (forget Venus, it is much too hot). That doesn't mean it won't be possible some day but right now we don't have the technology to pull this off, by far.]
Have we entertained the idea of creating an ozone layer on mars (or earth)? Some ideas on terraforming Mars
Is Frank Drake's equation for life on other places pretty accurate? [Yes, there is nothing wrong with the equation, except we don't know what actual values to plug in for most of the variables it has. So, it is a description that is valid, but until we know all the variables that go in it, it will not let us calculate reasonably certain results.]
Does Man have specific messages being sent out to outer space? [Not really, we have sent a few specific messages but not with the expectation that they will ever be picked up. It has been more symbolic in nature. Not much money has been spent on this either.]
Why do we continue to search for life when:
a. The Drake equation shows that the probability for finding intelligent civilizations is slim to none;
b. Considering the first point, even if there was a good chance of intelligent civilizations being out there - we don't even know if they are looking for us too.  We send silly messages in binary codes but we don't even know if they could decode it, much less care! Why continue to spend money ??
[The Drake equation doesn't tell us anything, since we don't know how to estimate the values that go in it. In other words, as of now, no one can proof or know whether the likelihood of finding intelligent civilizations is low or high. No one. That is why much of the current debate is somewhat philosophical in nature. For scientists the only way to proceed is to improve the data. That is why the focus is there, not on looking for alien signals, but on improving our ability to find other planets that look like they might be good for sustaining life. Only private funding is spent on SETI, no tax dollars.]

Black holes and other strange objects or concepts
If the center of a galaxy is a black hole, then why does the center appear to give off such a bright light? [A black hole itself is dark. If no matter is falling into the black hole, it is "dormant" and we can only find it through the effects of its gravity on surrounding stars. If matter is falling towards the black hole, it settles in an "accretion disk" around the black hole. This accretion disk gets very hot and as a result emits lots of light. It also causes many other effects, such as energetic outflows. Note that in most galaxies we see the center to be bright because of the stars concentrated there, we can't really see the tiny bit of space occupied by the black hole directly.]
What is a vacuum? [Absence of all matter, in particular not even gasses.]
How do we know the Earth and Sun can't become black holes? [Most objects are in balance between gravitational contraction and pressure. They don't have enough mass to ever get gravity strong enough to keep compressing the matter into a black hole. The sun will wind up as a white dwarf, with about 1000000 times its current density when it runs out of nuclear energy in the core. A white dwarf is a stable object that will not compress further. Very extreme, but nothing like a black hole. The earth will remain as it is, because its mass, hence gravity, is too weak to lead to further compression. Things cannot just change into black holes, they must have enough mass to overcome the pressure they provide to resist collapse.]
When talking about the time paradox in space, are we talking about the movement of the clock's hand or actual time? [Both, since if the clock is accurate it presumably measures the actual time that passes.]
What exactly are quasars? [Black holes in centers of galaxies that emit a lot of energy from their accretion disks that surround the black hole.]
Do we know anything about "worm holes" or is everything just based on speculation? [Speculation, from my perspective. But some people surely know much more about this than I do.]
What is the escape velocity around a black hole? [Depends on the distance to the black hole, just as it does for any object. The escape velocity goes as sqrt(2GM/r^2) for a spherical object. For black holes, we can make r so small (so close to the black hole) that the escape speed equals the speed of light. This radius is called the Schwarzschild radius. Not even light can escape from inside that radius.]
How do black holes form, do we even know? [Black hole evidence comes from binary stars where one of the companions is invisible but known to be massive from the motion of the visible star, and from centers of galaxies where we can measure the motion of stars or gas very close to the center and infer the mass that must be present in that very small volume to account for the measured velocities of the stars.]
How much do we know about black holes? [I would say: that it is highly probable they exist. That we find them in "stellar mass" ranges and much more massive (millions of solar masses), that they form from collapse of massive stars. That every massive galaxy seems to have one at its center. Other than that, it becomes less certain.]
What happens to the planets that are consumed by a black hole? [Anything falling into a black hole just adds to the mass of the black hole.]


Galaxies
How do you define a galaxy. [Large gravitationally bound system of stars that stays bound together]
How fast does a galaxy travel? [Objects in the universe move mostly under the influence of gravity and, on larger scales, due to the expansion of the universe. Locally, galaxies attract each other and their velocities are a result of this gravitational force they feel. Typical velocities are hundreds of km/s]
What is at the center of galaxies? [Usually a black hole. Our Milky Way galaxy has a 2 million solar mass black hole at the center.]
If we life in a Spiral Galaxy, where exactly are we located in that galaxy? [We are located in the "suburbs", inbetween two spiral arms, about 25,000 light years from the center. The best bar is in the center (really!).]
If our Galaxy collides with another galaxy could it do damage to our solar system and the way our planets rotate around the sun? [That depends. Distances between stars are very big, so we are unlikely to suffer any "direct hits". The most dramatic effect would be how our overall galaxy would change.]
Can solar systems separate from galaxies? [No, stars generally don't escape from galaxies, unless they are near the outskirts and moving at high velocities.]
What arm of the Milky Way are we in? [We are inbetween two arms.]
 How do we get pictures of our own galaxy? [We can only take pictures from "within", that is, we can not get an outside view. However, we can combine pictures to obtain a view of the entire sky which shows the Milky Way band and the direction of the center very clearly, at many different colors.]
 Do we know what causes the shape of galaxies? [Mostly gravity. All that mass in stars and gas is attracting each other, galaxies collide and merge under gravity, and the combined result over time gives a galaxy its current shape.]
How fast are we spinning around the center of the milky way galaxy? [220 km/s, we go around once every 200 million years or so. The solar system has circled the milky way center 20 times it its life time.]
How often is a new star born? [In our Milky Way, on average, every year about 2 to 5 solar masses of gas are turned into stars.]
Do other galaxies within the universe have stars as bright as the Earth's sun? As hot? As big? [Yes, many more that are like Sun or smaller, but there are many bigger stars too. Generally, a more massive star is bigger, hotter, and brighter than the Sun]
What kind of galaxy do we live in? [A spiral galaxy.]
How are galaxies named? [Official names usually involve the name of the survey that found it with the object's coordinates in the sky. Unofficial names can be chosen by the discoverers.]
Do all galaxies span across two dimensions and not three? [No, all galaxies span across 3 spatial dimensions (even if some are rather flat) and all galaxies span 4 dimensions in space-time, just like we do).]
What is dark matter? [Unknown matter that seems to be present based on the force of gravity we see in galaxies, but we don't see the mass that should cause this gravity.]

Cosmology
How does  the universe expand and how much? [It expands as a result of the initial energy release in the Big Bang. The current rate of expansion is 70 km/s for every length of three million light years; that is actually a very small expansion! At this rate it takes about 10 billion years to double in size. However, the rate of expansion is actually accelerating, so the actual doubling time is less.]
Are there any other scientific theories concerning the creation of the universe besides the Big Bang theory? [There was the "Steady State Theory" in the 1950s, which assumed that the universe was unchanging in time and place. This required continuous creation of new matter to make up for the expansion (i.e. decrease in matter decrease). The model fell out of favor with the discovery of the microwave background as evidence of the hot big bang.]
Before the Big Bang, what occupied the space the Big Bang later covered as it expanded? [Space-time is created as the universe expands. There is no pre-existing space to expand into.]
Do we have any idea of the shape of the universe? [This is one of the cosmological questions. Is the universe "closed" or "open" (this has to do with its geometry, is it "flat" or "curved" (in 4 dimenstions))? Is it infinite in size or finite in size? Current thinking favors a universe where the density is just at the critical limit between open and closed. We don't know if the universe is infinite or finite.]
How do you know how old the universe is? [In principle, this is a straightforward measurement: measure the distance between us and a distant galaxy that is moving away from us. Its distance and its velocity tells how long ago the two galaxies were very close together. For a uniformly expanding universe, any galaxy pairs should give you the same answer. In reality, the test is complicated since we don't know if the rate of expansion was the same throughout the age of the universe. We would expect gravity to slow down the rate of expansion continuously. However, evidence now indicates there is a mysterious "dark energy" in the universe which actually leads to a currently accelerating rate of expansion. Cosmological models and data can account for all observations, even though we don't yet know what this dark energy is, and give a very precise age for the universe. It is close to 13 billion years.]
Do we know where the center of the Universe is? [There is no center.]
Is it possible that the universe's expansion is pushing out as opposed to being pulled? [See the discussion under the age of the universe; yes, the expansion is "pushing out" due to dark energy, contrary to earlier expectations.]
What caused the big bang? [If you discover that, you will win the Nobel prize.]
How do we know how much mass the universe has? [We don't actually need to know the total mass so much as the density of mass. The latter we can measure by adding up all the visible mass and the mass indicated by gravity in various regions of the universe by stydying the galaxies in those regions.]
Does our galaxy move within the universe or is it stationary? [Our galaxy has its own motion with respect to the microwave background because we are falling towards other galaxies, and our Local Group of galaxies is falling in to the Virgo Cluster of galaxies. I believe our "peculiar motion" is about 600 km/s, which is typical for many galaxies.]
 What is a redshift and what does it tell us about galaxies and stars? [Wavelength or "color" shift in the light due to objects moving away from us (red shift) or moving to us (blue shift). It is called the Doppler shift. It doesn't tell us much about the galaxies or stars themselves, it just allows us to measure their relative velocity with respect to us. The amount of the wavelength shift is proportional to the velocity difference between us and the object.]
Is it safe to say that the Universe has been expanding over time at a constant rate? Or does the rate at which the universe expands constantly change? If so, how can we determine this? [No, the universe likely has not expanded at constant rate. Gravity would slow down the rate of expansion, while recent discoveries show that there has to be a "dark energy" since the expansion rate is actually accelerating, not slowing down. We can determine this by comparing distances and recession velocities between galaxies in different distance ranges, e.g. if we compare how fast the expansion is between very distant galaxies, we are looking at the expansion rate earlier in time in the universe, while if we look at relatively nearby galaxies we are looking at the current rate of expansion.]
Is there some sort of balance in the universe that it must maintain, e.g. if one star dies does another form? [No, there is no such guarantee. The universe might well evolve in a one-way direction with objects gradually cooling off and eventually no new stars to form as we run out of gas.]
How cold would it be if there were no stars in space? [Everything would have at least the temperature of the microwave background radiation, which is about 2.7 degrees K now. Very cold, but not zero.]
What was Einstein's idea of bending the light all about? [Space-time is flat except in the neighborhood of massive objects where it is curved. Light will follow space-time, hence follow curved paths near massive objects.]
Do astronomers see light as photons, as waves, or both? [Both.]
Is it at all possible to overcome the communications problem of space communication (like having to wait 20 minutes for information to go back and forth)? [Not as far as we understand physics now.]
Matter can neither be created nor destroyed. What kind of matter has been created from light in high energy physics labs? [Correction: "mass-energy" is conserved, not mass it self. Mass can be turned into energy and vice versa. The matter created from energy in high energy physics labs are "elementary particles" that often are unstable and disappear again. Also electrons and their anti-particle (positrons) are created.]

Other
Is the study of astronomy and its discoveries different in different parts of the world? [Not as a science. Each of the nations taking part in the scientific process have generally embraced the methods of scientific research, and, like many sciences, astronomy is a very international enterprise with international meetings, workshops, collaborations, etc. From a cultural perspective, there will certainly be differences on how society looks at the astronomical discoveries and tries to make sense of them in their own cultural perspective.]
 How many falling/shooting stars happen in one nightfall? [Many, sometimes more when the Earth moves through the dusty remains of a comet; we call that a "meteor shower".]
Can all space debris reach the earth's surface? [Yes, sometimes big chunks fall down.]
 How will the asteroid 2029 look like to us from Earth? [Pretty much like a fast moving faint dot of light (we hope).]
Does the Earth revolve around its axis perfectly, or is there a "wobble" that occurs over time? [The Earth's axis wobbles, it is called "Precession". The motion is like that of a wobbling spinning top. The reason for the precession is the gravitational pull of the moon and sun, the fact that the Earth is not quite rouond, and that the earth's rotation axis is tilted at 23.5 degrees. The period of precession is 26000 years; Polaris was not the north star at the time of the pharaos in Egypt. Note that the Greeks Hipparchus already discovered this motion as reflected on the motion of objects in the sky.]
 I have heard a rumor that a test satellite is supposed to fall out of orbit, will it burn up in the Earth's atmosphere or will it fall to earth? If so, how bad will the outcome be? [Pieces of it could make it through the earth's atmosphere intact, so depending on where they land that could be an issue. Also, the US might not want it to land just anywhere, since it is a spy satellite. Current plans seem to be to destroy it with a missile before it would re-enter the earth's atmosphere.]
Because stars have so much mass does that play into part why stars "fall" or "shoot"? [Shooting stars are small dust particles entering the Earth's atmosphere. The particles heat the surrounding air by friction, causing it to glow. Shooting stars have nothing to do with actual stars. It is just a historical name given to the phenomenon of a fading streak of light visible on the sky sometimes, also called a "meteor".]
Do radioactive elements decay at the same rate in different environments, e.g. a nitrogen atmosphere? [Yes, essentially the radioactive decay is a natural process that happens at the same rate whether we put e.g. uranium on earth or in vacuum. Only in special conditions can we cause a "chain reaction" where we produce a very rapid decay of many nuclei by creating special conditions.]
How do you determine an element's half life? [Even if the half life is long, a piece of material has an enormous number of atoms/nuclei in it, so you can measure a rate of decay (e.g. with Geiger counter) and from that the half life given you can know how many unstable nuclei the piece of material has (from its mass and chemical composition.]
If free-falling simulates zero gravity, then why are you still falling? [This is a good question. You cannot tell you are falling if you can't observe the outside world, but you would be able to behave as if there were no gravity, i.e. make flip-flops, rotate, drink upside down, etc. Einstein realized that a situation of free-fall would be equivalent to no gravity for the person experiencing the freefall. The way to think about it is, that if you stand on a scale in an elevator, and the elevator goes into free-fall, you will no longer excert a gravitational force on the scale, since the scale is falling with you, and therefore your weight will be zero, i.e. you don't experience gravity.]
 What is the relationship between light and sound? (I've heard that light can be described as a very high pitch.) [Both are wave phenomenon. Sound waves require a medium to propagate in (e.g. air, water, a metal), while light waves can propagate in vacuum (light is an EM field that is not carried by a medium). Light waves travel much faster and occur over a much wider range in "pitches" or "frequencies".]
 Will science and religion ever agree on a common way that earth was created, evolution vs creationism (bible)? [Well, one can always hope, but something will have to give on the religious side (if you ask me) which is to open their mind to the possibilities that a book written thousands of years ago should not be interpreted literally, and that science is an ultimately an objective process that simply tries to determine how things happen under natural laws. The point of science is not to discredit religion; perhaps the universe and earth were created, however, that is not a question to answer scientifically, since it is essentially a believe in a miracle and miracles cannot be studied scientifically if they can never be repeated.]
What causes a comet to begin its journey through our galaxy? [Comets are solar system objects, meaning that they orbit the Sun. This means that they don't go roaming through the galaxy. They are probably made of leftover material from the formation of the solar system, preserved in the frigid conditions so far away from the Sun. Like everything else in the solar system, they orbit the Sun, but because they are so far away, it takes a long time for them to complete an orbit. Sometimes, as they're going around, they happen to pass by a large object (like Jupiter) which tugs on the comet and changes its orbit such that it ends up hitting something.]
When asteroids hit Jupiter a few years back what did it impact since Jupiter has no solid surface? [We talked more about this in class, but basically they pummeled into the atmosphere. The fragments could only go so far in before disintegrating; gasses do provide resistance, it is not a vacuum! The actual explosion is not all that different in terms of  the energy released during the impact.]
Where is the most powerful telescope? [This question cannot be answered, since it depends on the application and the science you are trying to do. E.g. do you want to observe in the visible, or at radio or X-ray wavelengths? Do you need sensitivity for faint objects or a wide field of view for your science? The biggest optical telescopes these days are 10 meters in diameter, the biggest radio telescope is 300 m in diameter, the most sensitive optical telescope for stars is the Hubble Space Telescope (even though it is not the biggest at only 2.4m diameter). The radio telescope with the highest resolving power is the VLBA which has telescopes on several continents.
Who was the first person to develop the telescope? [This depends on who you ask. Hans Lippershey (c1570-c1619) from the Netherlands is often credited with the invention. What is less disputed is that Galileo Galilei was the first to systematically use the telescope for astronomical observations.]
Does a telescope allow us to see into the future? [No, telescopes actually see things they were in the past, the further away the object, the more in the past we see it.]
What is a libration point? [See this link: http://en.wikipedia.org/wiki/Lagrangian_point]
Would it ever be possible to create an artificial gravity device that you could place in a space ship so people don't float about? [Yes, a giant rotating "wheel" in space would have produce "artificial gravity" due to the centripetal force. If you stand on the outer walls of this spinning wheel, the centrifugal force would force you outwards as you are spinning along with the wheel, the walls of the wheel would push back on you giving you the feeling of gravity. The size and spin rate of the wheel would allow you to set the gravity level you want.]
When traveling in space or to the moon, how does the lesser amount of gravity affect the human body? [See question above. You can find lots about this if you do a bit of searching on the web.]
Would it be possible that entropy increases because there are more orderly things that have the potential to become disordered? Would entropy drive evolution, because mutations mainly occur by chance? [Both of these last two questions are good and not easy to answer well because thermodynamics is a complex topic. Entropy has a well-defined definition in phyics and from that perspective the answer is no. The increase in order is not driven by entropy but by "organizing forces" such as e.g. gravity in the case of structure in space and chemical reactions in the case of mutations. So suppose we would not have chemical reactions between elements but we would have brownian motion of atoms and molecules, the way we now do. Things would still get mixed up, increasing entropy (e.g. paint of different colors put in the same container). In the presence of the ordering mechanisms, the entropy of the entire system still goes up because other parts of the system become more disordered while the order increases in some parts. The difficult thing is to know what constitutes the "closed system" for each problem under discussion.]
What would the "missing link" clarify for science and creationism? [That depends on what one would consider to be a missing link and how much trouble you have accepting scientific results. For example, for some the "missing link" is the "creature" between apes and humans. Probably for many anthropologists and biologists this question may have already been answered since many skeletons over a wide range in time have been found to trace back human lineage. To others it might be the "first living thing", since we haven't been able to create life out of non-living matter in a laboratory and we don't know how it happened on Earth 3.5 billion years or so ago. Those who want to bring the world of science into agreement with creationism, will always find stumbling blocks because the alternative is simply not acceptable.]
Can light be destroyed? Light can be absorbed by matter (and matter can also emit light). When light is absorbed, its energy goes into heating the matter when it is not re-emitted. That means that the energy contained in the light is not lost, but passed on to the matter. Energy is conserved.