1. “What in the World is an ‘Exoplanet?”.  Write 10 – 15 sentence summary of this article.

https://www.nasa.gov/feature/jpl/what-in-the-world-is-an-exoplanet

2.“’Exoplanets’ and the Search for Habitable Worlds”. Write 10 – 15 sentence summary of this article.

https://www.jpl.nasa.gov/edu/news/2015/8/17/bringing-earths-cousin-into-the-classroom/

1. List the two main groups of planets, and the names of the planets that belong to each group. Which group of planets have higher average mass and which group have average density?
   1. ____________________________________________________________
   2. ____________________________________________________________
2. What is an Exoplanet and describe the technique Kepler planet finding mission uses to find exoplanets? ____________________
3. Name two types of objects that orbit the Sun but are not classified as planets.
   1. ____________________________________________________________
   2. ____________________________________________________________
4. Why do the tails of comets always point away from the sun?  __________________________________________________________________
5. An element has a half-life of 120 years.  A given sample originally contained 1000 grams of this element.  After 480 years have passed, how many grams of this element  remain in the sample?  ______________________ 
6. According to radioactive dating of meteorites, what is the approximate age of the solar system?  _____________________________
7. The most accepted theory for the formation of the solar system is called the ______________________ theory. Give a short description of this theory.  __________________________________________________________________
8. Why are the oldest Earth rocks younger than the oldest moon rocks?  __________________________________________________________________ 
9. Describe and differentiate Meteoroids, Meteors and Meteorites. ___________
10. In our solar system, which planet has the greatest uncompressed density, and what does that tell us about its composition?  __________________________________________________________________
11. What is the difference between condensation and accretion?  __________________________________________________________________
12. After the planets formed, the remnants of the protoplanetary nebula disappeared.  Give four reasons for this disappearance.
    1. ____________________________________________________________
    2. ____________________________________________________________
    3. ____________________________________________________________
    4. ____________________________________________________________
13. Name and describe three possible ways to detect an extrasolar planet.
    1. ____________________________________________________________
    2. ____________________________________________________________
    3. ____________________________________________________________
14. “Asteroids, Comets, Meteorites”. Write 10 – 15 sentence summary of this article.

https://www.jpl.nasa.gov/asteroid-watch