World-Wide Web (Extra-credit/Make-up) Exercise

Please allow yourself two hours to complete this extra credit exercise. The computer lab on campus in Jacobs Hall has Macintosh computers available with all of the appropriate software. Those more comfortable using PC's are welcome to use Explorer. We will assume that you are familiar with web surfing, and you do not need assistance. All web browsers work in a similar fashion-there is a box to enter a web address. To start this exercise type in the following address:

This will bring you to the Astronomy 110 World Wide Web (WWW) exercise. Once you are here, you may click on the underlined boldface titles called links ("Picture of the Day", "NSSDC Photo Gallery", etc.) and explore these sites, then return to the 110 exercise page by hitting the "Back" button. Note that you may have to do this a few times before you are returned to the Astro 110 WWW page. Some of the links may open up a separate Netscape window, so if the back button doesn't work, just look to see if your original window is behind the one you are looking at. Once you've explored a page, answer the question related to that page in the box provided. Use the mouse to click in the box; this makes the box active and anything you type will appear in this box. Make sure that when you click in a box you see the cursor appear and that when you type you are able to see the text. If this is not so, double check that you have clicked in the box you are typing in. Otherwise you may be typing in a previously active box. You may also want to write your answers down on a piece of paper in case the answers you typed for earlier questions gets erased. This should not happen, but if it does, just answer the questions on a piece of paper, and then type them all in at the end.

When you are finished with the six sections, type your name, professor's name, and your TA's name in the appropriate boxes (to go from one box to another, either click in the new one with the mouse, or simply hit the ``Tab" key). We would also appreciate any comments and/or suggestions you may have on this exercise and homepage. Once you are all done, print out the entire lab and hand it in to your TA.

We have also provided you with some fun and/or useful links for your own browsing. If you enjoy the project and want to see more, click on the "What's New" and "What's Cool" boxes in the second row of buttons. There is a lot of information out there on the internet - now it's at your fingertips!

Once you've completed the exercise, a print out of your answers must be turned-in to your TA in the Astronomy Department. It's best to hand this sheet into your TA when you've finished the project. Your TA will look at your answers and give you extra credit points based on these answers.

If you have problems with this exercise, don't hesitate to ask the Jacobs Computer Lab personnel for help. They are well versed in the use of web, and if you explain to them that it's for a class, they will be more than willing to help. On the other hand, try to figure things out for yourself first - this is your project, not theirs!

During the semester you will be required to make observations from your home while completing one or more of the projects described below. Your TA will tell you which ones you must complete. Note that not all of the projects listed here can be completed during every semester due to the changing positions of the planets. Everyone, however, will have to complete the ``Observatory Notebook'' section which requires you to attend the monthly observing session conducted at the campus observatory.

The goal of this semester-long project is to get you outside observing the night sky. This includes tracking the phases of the Moon, identifying and observing the planets and tracking their motions, and finding constellations. To perform this lab properly, you will have to record your work in an observing notebook, and learn how to use the star charts at the back of the lab manual. So, obtain a small spiral notebook, or some other set-up that allows you to write down your observations and keep them organized (having a bound notebook is useful due to the windy conditions that frequently occur in Las Cruces). This project is worth two regular lab grades, and should be taken very seriously! Your TA will tell you which exercises to do, and how many points each one is worth. Note that all of the observing projects must be started as soon as possible to insure that bad weather does not eliminate the possibility of making your observations. This is especially true of Exercise #3, since you need to track a planet for the entire semester to insure you detect its motion.

Warning: Due to the fact that sky is constantly changing, and astronomical events/objects can only be seen at certain times, it is impossible to cheat on these observing projects! We will know whether you actually observed what you said you observed. So, do not even think about risking the failure of this project (and possibly this course!) by faking your observations, or plagiarizing your friends or any other sources of information.

After choosing the site for your observatory, you must then find the directions of the cardinal points (North, South, East and West). To find the direction of West is probably the easiest: simply note the point of sunset on one evening early in the semester. This is West. If you face due West, and stick out your left hand horizontally, it will be pointing South. North is directly opposite South, and East is directly opposite West. Note these directions so that you can orient yourself each time you observe. You then need to have a watch, a flashlight, a pencil and your notebook for all of your observing projects.

The goal of the first project is to get you familiar with the motion of the Moon, and the changing phases of the Moon. Using a calendar, or asking your TA, find the dates of the next New and Full moons. For this exercise, you will track the phases of the Moon as it progresses from New to Full. This exercise will require you to go outside on eight different nights over a two week period, one time during the semester-DO NOT LEAVE THIS PROJECT UNTIL THE LAST MONTH OF THE SEMESTER!!! If so, you might not have good enough weather or time to allow you to complete this exercise. You need to conduct this project from your observatory site.

Step #1: Find the date of the next New Moon. As you have found out in your lecture class, during New Moon, the Sun, the Earth and the Moon are all on a straight line. At the time of New Moon, the un-illuminated side of the Moon is facing us, and the Moon is located close to the Sun in the sky. Thus we cannot see the Moon during its New phase (unless there is a solar eclipse!). It is usually not possible to see the Moon until two full days after New. Among amateur astronomers, there are contests on who can be the first to see the Moon after a New Moon. The record is 12.1 hours after New Moon. For most people though, it is difficult to see the Moon much less than 24 hours after New Moon. For people in the Northern Hemisphere, however, the days following the New Moons in February and March offer the best chances for seeing a ``young Moon" because the tilt of the Earth's axis with respect to its orbit places the Moon vertically above the point of sunset during these months. Given a clear western horizon, and a pair of binoculars, you might be able to see a very young Moon yourself.

Step #2: Beginning (one or) two days after the chosen New Moon, go out about 20 minutes after sunset and look for a very thin crescent Moon near the western horizon. Can you find the Moon? Either way, note the time of your observation in your logbook, and whether you were successful at seeing the Moon. If you saw the Moon, draw a sketch of its appearance. [For this sketch, it might be handy to find a can, a bottle, or drinking glass that is about 2 to 4 inches in diameter and use this to make a perfect circle for the Moon, and then shade in the part you cannot see to render a drawing of the phase of the Moon. Use the same circle-maker for the entire exercise.] In your notebook note the time and date of this observation along with your drawing. Note whether there are any bright stars or planets near the Moon.

Step #3: You must attempt to observe the Moon three days after the time of New Moon. Make a drawing of the phase of the Moon and note the time and date. Observe the Moon about 30 minutes after sunset so that it is fairly dark (the time of sunset can be found in the newspaper or on one of the evening weather forecasts). Besides the bright crescent, can you see the other parts of the Moon glowing faintly? Within a few days after New Moon, it is often quite easy to see the ``dark" portion of the Moon (the part not directly illuminated by the Sun). This phenomenon is called ``Earthshine", or ``the old Moon in the New Moon's arms". For step #3, you need to research the nature of Earthshine. You can use the web (for example enter ``Moon and Earthshine" on Google or another search engine) or look in a book to find out the cause of Earthshine. Write-up a paragraph or two in your observatory logbook describing the phenomenon of Earthshine, with a drawing/diagram showing how it arises.

Step #4: Continue to observe the Moon every other day until the Full Phase, and make sure you observe on the night of the Full Moon! Note the time and dates of your observations, and make drawings of the appearance of the Moon. Note the locations of any nearby bright stars or planets. Use the star charts at the back of the lab manual to see if you can identify which constellations the Moon happens to be passing through. Note that the star charts are different for each month, and that the positions of the constellations change throughout the night and month!

Step #5: Describe/summarize your observations of the Moon. When did the Moon reach a phase of ``First Quarter" (when was exactly one half of the Moon illuminated)? Was it possible for you to tell on which date the Moon was perfectly Full, or did it look Full to you for several days? Which direction did the Moon move over the course of this two week period? Did it come close to any planets? Any other interesting observations?

There are five naked eye planets: Mercury, Venus, Mars, Jupiter, and Saturn. All five of these can be easily seen (even in bright city lighting) if they are well placed in the nighttime sky. Your goal is to observe as many of them as possible. Due to the motions of the planets, not all five planets can be seen at any one time. For example, the planet could be located on the other side of the Sun from Earth, and be invisible to us. Usually, however, one or more planets is visible in the evening sky (if not, they are visible in the morning sky!). Your TA will tell you which planets are visible this semester.

Note that Mercury will just about always be the hardest of the planets to observe. It is only easily seen near the times of greatest elongation (see the ``Orbit of Mercury" lab for further details). Even then, you have to observe right before sunrise (greatest western elongations), or right after sunset (greatest eastern elongations). Mercury is fairly bright at these times, so it can be seen easily with the naked eye, but you must have a clear horizon to have any chance of seeing it. There are several methods to identifying the planets. Perhaps the easiest is to have one of the TA's at the observatory session point them out to you. But we would like you to be able to search for and find them on your own. One way is to use the sky charts in the back of the lab manual. Read about how to use those charts, and then orient yourself by identifying some of the constellations in the nighttime sky using the sky charts. So, if you are told that ``Saturn is in Leo", you can go out, find Leo, and see that there is a big, bright star there that is not on the sky chart.

But there are two other good sources: online, or in a magazine. ``Sky & Telescope" and ``Astronomy" are magazines for the amateur astronomy community. Sky & Telescope is a more advanced magazine than Astronomy. Both magazines can be found in our library, or at a book store (such as that in the mall). Inside these magazines are monthly columns that talk about which planets are visible, and where they can be found (including sky charts). In addition, however, both magazines have websites (www.astronomy.com and www.skypub.com). Both websites have interactive sky charts that show where the planets are in the sky. At the Sky & Telescope website, hit the ``Interactive Sky Chart" link. At the Astronomy magazine website, after you register (its free), you can access the skychart by clicking on the link ``The Sky Online for Beginners" found on the lefthand side of the main webpage (note that it reads your zipcode to figure out your latitude to make a chart just for you!). The yellow line that runs across the resulting skymap is the ``ecliptic" (the plane of the Earth's orbit), and all of the planets will be found close to this line. Note where these planets are with respect to the stars, and find the same constellations on your skycharts and make a little note on the chart so that you can find the planet when you go observing.

Step #1: During the semester identify as many planets in the night time sky as possible. Write down the details of the time and date of your observations, and constellation in which you found the planet. Mark the location of the planet on the appropriate sky chart (make sure to turn-in this chart, or a photocopy/handmade version of this chart, with the rest of your materials at the end of the semester). Note that the planets are just about always the brightest ``stars" in each constellation, and thus are very hard to miss! You should conduct this exercise from your observing site (unless your western horizon is not good enough to allow you to see Mercury-if so, you can observe Mercury from the campus observatory, or some other site with a good western horizon).

Step #1: Identify the constellation where your TA says the planet is located. For all of the planets except Venus, go out after about 9 or 10 pm early in the semester (dress warmly!!). As the semester progresses your planet will rise earlier, and earlier, and near the end of it semester will be visible right after sunset. If the chosen planet is Venus, you will need to go out about 20 minutes after sunset to find Venus. Venus is the brightest star-like object in the entire sky (only the Sun and Moon are brighter). Note in your logbook the time and date when you finally identified the constellation containing your planet (it is quite possible that the planet will actually move from one constellation to another during the semester).

Step #2: Identify the chosen planet. This is easy-in fact, it might be easier for you to first find your planet AND then identify the constellation it is in! Normally, the planet chosen for this exercise will be the brightest object in the nighttime sky after the Moon. Sometimes, however, Mars and Saturn can be fainter than some of the brightest nighttime stars. Note the time and date when you first found your planet.

Step #3: Marking the position of your planet on the star chart. This is the hardest part of the lab. It is likely that you will require a better star map than those in the back of the lab manual to properly keep track of your planet. If it is not contained in this manual, your TA will give you a handout with a blown-up version of the constellation/sky region containing your planet. Use this star chart in concert with those in back of the manual to identify the names/letters of the brightest stars closest to your planet. Note that the brightest star in a constellation was usually given the designation $\alpha$ (= ``Alpha'')), the first letter in the Greek alphabet. This progresses all the way to the last Greek letter Omega ( $\omega$ ) [For more on the Greek letters, see the little table on cover page for the sky charts at the back of the lab manual.] After that, the fainter stars were given numbers. If you have too many bright lights near your observatory site, you might not be able to see very many of the stars marked on the close-up chart, and might have to conduct this exercise at a location where the sky is a bit darker. If you are still having trouble seeing many stars, see if you can borrow a pair of binoculars to help you better identify the stars near your planet.

Step #4: Tracking the motion of the planet by plotting it on the chart/map designated by your TA. Usually the planet will spend the entire semester on this chart. For some fast moving planets (Mars and Venus), you might need to use more than one chart. If you are given a worksheet, it is likely that there is a dotted line that goes from one side of the chart to the other: this line dilineates the ecliptic, the apparent path of the Sun through the sky (the projection of the Earth's orbital plane). Most planets are found close to the ecliptic. Use this worksheet for plotting the position of the planet. Using the skychart from the back of the lab manual, and/or the worksheet, locate the position of the planet in the sky. Mark its position on the star chart with the date of observation. Note in your logbook the time of this observation. Every week or ten days, go out and observe the planet, and plot its position on your worksheet. You should have ten observations spanning nearly the entire semester to complete this project.

Step #5: Summarize the motion of your planet during the semester. How far did the planet move? To do this, note that the little squares formed by the grid lines in the close-up sky chart are exactly one degree on a side. How many degrees did your planet move? Given that there are 360 degrees in a circle, how many months will it take your planet to move completely around the sky? Which direction did it move during the semester? Did it follow the ecliptic, or did it move north/south of the ecliptic? Why do you think it did this?

Step 1: Look at the various star charts for the different months that occur during this semester. Find a constellation that intrigues you [unless your TA gives you permission to do so, please do not choose any of the constellations ``highlighted'' in the sky charts at the back of this manual!]. Remember, not every constellation found on these charts is going to be visible to you. Sometimes a nearby building, tree, or mountain may block your view of a particular constellation. Note that over the course of the semester some constellations will disappear from view in the West, while others will appear in the East. This ever-changing sky is due to the Earth's motion around the Sun. After you have decided on a constellation, find out the best time to observe it (note that if you stay up late, the constellations seen in the later months of the semester can be seen near midnight at the beginning of the semester). Go out and find your constellation! Write-up a description of how you found it. What was the time and date that you first found your constellation? Was it in the West, straight overhead or in the Southeast, etc. ?

Step 2: Use the internet or a book from the library to research the mythology of your chosen constellation. Note that some constellations are modern creations, and do not have a mythology associated with them. If you chose one of these less interesting star patterns, why not go back and choose another (generally larger!) constellation. Most of our constellation names and their mythologies come from the Greeks and Romans. But just about all of the major cultures on our planet have created constellation mythologies. See if you can find one of these alternative stories for the stars of your chosen constellation (one example is the constellation Orion described in the constellation highlight for February). Are there any interesting or famous objects located in your constellation (star clusters, planets, galaxies)? Do any of the stars have interesting or unusual names with their own stories? Your mythology write-up should be one page singlespaced, two pages doublespaced. Please list the references/websites you used to learn the constellation's mythology.

Step 3: Creating your own constellation. Without using a star map, just sit back/lay down one evening and stare at the stars. Do you see any familiar patterns amongst the stars? As you have probably noticed, many of the classical constellations do not resemble the objects they are suppose to represent. They were created to honor an important character that occurred in one of that culture's stories (and sometimes history). So, your constellation doesn't have to be a perfect representation of the object it is suppose to represent.

Observations are the fundamental tool of the astronomer. Astronomers cannot go out and collect objects of study as a biologist, chemist, or geologist might. They must sit on Earth and study images or pictures of astronomical objects and learn what they can from these images. This may seem like a difficult task, trying to learn from pictures, but light holds a vast amount of information. By studying objects in the sky at different wavelengths, we may learn a great deal about what is happening at great distances.

Before the invention of photographic film, astronomers made images of the sky by sitting in front of a telescope and carefully drawing what they saw. Many fantastic discoveries were made this way. The discovery that the Horsehead Nebula changed shape over several years was made by comparing two accurate drawings made over a span of a few decades. Galileo observed the motions of Jupiter's moons which confirmed the Copernican model of the solar system. Galileo also observed and drew sunspots proving that the Sun was not a pristine perfect object, but was in fact active and changing all of the time.

Your task over the course of the semester will be to keep an Observatory Notebook. In this notebook you will draw pictures and give descriptions of many different types of objects you will see in the sky with the help of the telescopes at the campus observatory.

Attend the campus observatory several times throughout each month until you have seen the required number of objects. Your observations will be due at the end of every month. Because the skies change over the course of the semester, objects which are visible one month may not be visible the next month. For this reason, if you miss an object one month, you may not make up that observation. If you observe less than the required number of objects for one month, you cannot make up the missed points the following month. Please keep this in mind when you attend the observatory sessions. It is usually possible to obtain all of your observations in one night, especially if it is not too crowded, and the weather is clear. Hint: GO TO THE CAMPUS OBSERVATORY NEAR THE BEGINNING OF EACH MONTH TO AVOID THE LAST WEEK RUSH!! Also remember that even if it is cloudy the entire last week of the month, you are still responsible for the required number of observations!

The following sheets are the observation notebook worksheets; TAKE THESE WITH YOU TO THE OBSERVATORY and fill out one of these sheets for each object you observe. When you attend the observatory sessions, a TA will be present to assist you with the telescope and give you some important information about the objects you will be viewing. After you look at the object through the telescope, take some time to draw a sketch of what you saw. In the approrpiate spaces, write down the date, time, description of the object, observing conditions, which of the telescopes was used, and any other details you think are important. Have the TA initial each sheet as proof of your attendance to the observatory session that night. Before turning in your notebook each month, you should also look up some information about each of the objects and write it down under the description section of the corresponding notebook page.