ASTR 110 M04,M05,M06 - FALL 08 - Holtzman

Review list for final

• Understand what a scientific theory is, and how data is used to constrain scientific theories. Understand the difference between astronomy and astrology.

• Know the objects in the Solar system: Sun, planets, moons, asteroids, meteors, comets. Know what a shooting star is.

• Know how the Sun is one of many stars that make up the Milky Way galaxy; know about the variety of stars in the Galaxy. Know what shape the Galaxy is and what it contains. Know the main different types of galaxies.

• Understand rough relative sizes of objects: Sun, planets, stars, Milky Way, galaxies, and know what each of these objects is. Know what a light year and an astronomical unit is.

• Understand the motions of objects in the Universe: planets around the Sun, stars moving inside of galaxies. Understand the observation that galaxies all appear to be moving away from us and the implication that the Universe is expanding. Understand the basic ideas and justifications for the Big Bang theory.

• Understand motions of objects in the sky as seen from Earth, which result from a combination of our motion (reflex) and the intrinsic motion of the object. Understand revolution and rotation of planets. Understand apparent motion of stars, Sun with respect to the stars, and planets with respect to the stars. In particular, understand day and night and the path of the Sun and stars through the sky at different times of year. Understand parallax and how it is used to measure distances to stars.

• Understand how the rotation axis of the Earth is tilted with respect to its plane of revolution. Understand and be able to clearly formulate the reason we have seasons.

• Understand the orbit of the Moon. Understand the reason that the Moon has phases, and how the phases are related to the time of day/night when the Moon is seen from Earth. Understand what solar and lunar eclipses are and why they don't occur every month.

• Understand the motions and appearances of the planets. Be able to figure out whether planets have phases when you look at them. Know what retrograde motion is.

• Understand historically how humans have reached the present understanding of motions in our Solar System, e.g., the geocentric and heliocentric models and what observations motivated these models. Understand the contributions of Ptolemy, Copernicus, Galileo, Tycho Brahe, and Kepler.

• Understand Kepler's laws and be able to use them. Know the terminology which comes into Kepler's laws: ellipses, focii of ellipses, semimajor axis, eccentricity, period, astronomical unit.

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• Understand Newton's laws of motion and the law of gravity; understand how the law of gravity can be used to calculate the relative strength of gravity at different places, for example, your weight on different planets.

• Understand how Newton's laws can be used to understand orbits, and that Kepler's laws are a natural consequence of Newton's more basic laws about how things move. Understand Kepler's laws.

• Understand orbits: why objects can go around each other when the force of gravity is an attractive force between the two objects. Understand how our model for the formation of the Solar System leads to expectation that planets will have initial transverse velocities and thus will orbit the Sun rather than fall into it.

• Understand how masses of astronomical objects are inferred using our understanding of gravity and measurements of motions of objects. In particular, understand how we measure masses of planets and stars. Know ROUGHLY how massive these objects are: e.g., how massive are different planets compared to the Earth, and how massive are different stars compared to the Sun. Understand how we measure masses of galaxies, and know why we believe that there is a large amount of dark matter in the Universe.

• Understand the concept of gravitational lensing and qualitatively how it can be used to infer masses of objects. Know what a black hole is.

• Light. Know about the general properties of light, and the different forms that light can take (the electromagnetic spectrum), and how different kinds of light are characterized by different wavelengths or different energies. Know about the different kinds of spectra (continuous, emission line, absorption line) that objects can produce. Understand the types of spectra that different astronomical objects produce (e.g., stars produce absorption line spectra, etc.)

• Understand thermal (blackbody) radiation (continuous radiation from warm dense sources) and how it can be used to infer temperatures of objects.

• Understand the effect of dust in the interstellar matter (and in the Earth's atmosphere) on the colors of starlight. Know why the sky is blue and why the sun can appear to change color between midday and sunset.

• Understand basic atomic structure and how the different elements differ at the atomic level. Understand that atoms move and that the speed of their motion is related to the temperature. Know that normal matter in the Universe is primarily composed of hydrogen, with some helium, and very little of everything else.

• Understand how emission and absorption lines are produced, and how they are related to orbits of electrons in atoms. Understand how we can observationally determine physical properties by studying emission and absorption lines. In particular, know how we can estimate temperatures and compositions of stars.

• Understand how the total brightness of stars depends on the temperature, size, and distance of the star. Understand how we can use our previous estimates of temperatures (from colors and/or spectra) and distances (from parallax) to determine sizes of stars; know about dwarf stars and giant stars.

• Understand what a HR (color-magnitude) diagram is, and where stars fall in this diagram. Understand the terminology: main sequence, red giant, white dwarf.

• Know what the Doppler shift is, and how we can infer information about the radial velocities of astronomical objects.

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• Understand how we infer that planets in the Solar System have different compositions from simple measurements of their densities. Understand the concept of density and how it is measured. Know the different general classes of planets in the Solar System.

• Understand the reason we think that the inner planets are different from the outer ones: Only heavier elements can condense into solid form at the higher temperatures of the inner solar system at solar system formation. In addition, the ability of a planet to hold on to different elements in the atmosphere depends on the strength of gravity at the surface of the planet, as well as the temperature there, because the speed of atoms depends on the temperature and the mass of an atom.

• Understand the main processes which are important in the inner planets: plate tectonics, volcanism, erosion, and cratering. Know roughly which effects are dominant on which of the inner planets. Understand what we think these effects depend on and how: the presence/absence of an atmosphere and the presence/absence of a hot interior, and understand what it is about a planet that is likely to determine these. Know how we learn about the internal structure and processes occuring on Earth.

• Understand qualitatively what affects how hot it will be on planets. In particular, understand the greenhouse effect.

• Understand the similarities and differences between the moons of the outer planets and the inner planets, including the process of tidal heating which is important for the moons of the outer planets. Know about some of the interesting features of some of the big moons in the Solar System: the four moons of Jupiter (Io, Europa, Ganymede, Callisto) and Saturn's big moon, Titan.

• Understand how other planetary systems (planets around other stars) have been detected, and know how the things we have learned about other planetary systems have affected our ideas about the formation of planetary systems in general.

• Understand how energy is generated in the Sun by nuclear reactions. Understand what a nuclear reaction is, why they only occur in the centers of massive objects like stars, and what the main nuclear reaction going on in the Sun is. Understand how the pressure generated because it is hotter in the core of the Sun (and stars) balances gravity and keeps the Sun from contracting.

• Understand why the Sun evolves over the course if its lifetime, and know the main stages of its evolution.

• Understand how the evolution of other stars compare with that of the Sun, and how the evolution depends on the mass of the star. Understand the importance of massive stars and supernovae explosions in creating the heavy elements in the Universe.