1. The Solar System 1 _________________ 9 _________________ planets ________ (major) moons asteroids, comets, meteoroids

2. How are planet sizes determined? Measure angular size on sky, Then use geometry….. distances The distances to planets are known from Kepler’s Laws (once calibrated with radar ranging to Venus)

3. ____________ ____________ - determined through observing the gravitational effect of the planet on some nearby object (moons, nearby planets, satellites) __________________ __________________ - divide mass by volume Planets orbit the sun counter- clockwise as seen from the North Celestial Pole. All planets are in the same orbital plane ______________ ______________

4. ___________ Planets Mercury, Venus, Earth and Mars _____________ to Sun Small masses, radii Rocky, ________ surfaces High densities _____________________ Weak magnetic field No _____________ Few _______________ __________Planets Jupiter, Saturn, Uranus, and Neptune __________ from Sun Large masses and radii ______________ surface ___________densities __________________ Strong magnetic field Many ____________ Many _____________

5. Terrestrial planets

6. Jovian planets (and earth)

7. OTHER SOLAR SYSTEM OBJECTS

8. _______________ - rocks with sizes greater than 100m across Most ___________________ remain in the Asteroid belt between Mars and Jupiter but a few have orbits that cross Earth’s path. Three asteroids hit the Earth every _____________ _____________ _____________

9. Known asteroid impact sites

10. Asteroid sizes Asteroid sizes range from _______________________________ _________________________ _________________________ _________________________ They are composed of _________________________ _________________________ _________________________ The Asteroid belt is a group of rocks that appear to have never joined to make a planet. Why do we think this? Too _____________to be a planet Asteroids have different chemical compositions It’s all ____________________…..

12. Meteoroids – interplanetary rocky material _________________(down to grain size). called a _____________ as it burns in the Earth’s atmospherecalled a _____________ as it burns in the Earth’s atmosphere if it makes it to the ground, it is a __________________if it makes it to the ground, it is a __________________ Most meteor showers are the result of the Earth passing through the __________________which has left debris along its path

13. Meteor crater near Winslow, AZ - the culprit was probably 50 m across weighing 200,000 tons! Meteors are rocky - mainly iron and nickel Some contain carbonaceous material - rich in organic material Meteors are old - 4.5 billion years - based on carbon dating Meteor showers: Orionid – Oct 21/22 Leonid – Nov 18/19 Geminid – Dec 14/15

14. Comets ____________- dust and rock in ____________________ _______________________________________________ Halley’s Comet in 1986 All light is reflected from the Sun - the comet makes no light of its own The nucleus is a few km in diameter

15. Cometary orbits take them far ___________________ Many take up to _____________________________! Short period comets (< 200 years) (like Halley’s comet) Short period comets may have originated in the _______________________________________________ Kuiper belt comet gets “kicked” into an eccentric orbit, bringing it into the solar system These long period comets probably originate in _______________

16. Parts of a Comet Dust Tail Ion Tail Coma Nucleus

17. In Comparison ____________ occasional collide and break into smaller chunks of rock…. They are then identified as… _____________ : when a Meteoroid enters Earth’s atmosphere, it will burn up and form a streak of light called a meteor (meteor shower) Can sometimes also be icy. If the Meteor doesn’t burn up, it will impact Earth and it is then called a…._______________________ METEORITE….