ASTR 110 M02,M03,M04 - Fall 2013 - Holtzman

Review list for second midterm

Study the class powerpoint presentations at http://astronomy.nmsu.edu/holtz/a110/ppt and/or the class notes at http://astronomy.nmsu.edu/holtz/a110/a110notes. This midterm will cover Part III and the first half of Part IV (everying including motion, gravity, and determination of masses of astronomical objects). Review the Canvas homework assignments, and the in-class questions.

• Know the objects in the Solar system: Sun, planets, moons, asteroids, meteors, comets, Kuiper belt, planets and dwarf planets. Understand the concept of density and how we can use it to get some information about the composition of planets.

• 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, how we know this, and what the Milky Way contains (stars and interstellar matter). Know the main different types of galaxies.

• 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 each other and the implication that the Universe is expanding. Understand the basic ideas and justifications for the Big Bang theory, and how it is a good example of how the process of science works, including prediction and observation of the microwave background, etc.

• Understand rough relative sizes of objects: Sun, planets, stars, Milky Way, galaxies, and relative distances between them. Understand what a scale model is and how they work, and how to apply one.

• Understand how astronomers can measure distances to objects that are so far away using measurment of angles and also by studying brightnesses of objects. Know what parallax and the inverse square law of brightness are. Know some of the units that astronomers use to measure distances: the astronomical unit and units of light travel time (like the light year).

• Understand Newton's laws of motion: law of inertia, force law, and action/reaction. Understand the law of gravity and what the force of gravity depends on. Understand what the different basic forces are. 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 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 the 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.