1. Our Solar System Assignment #44

2. The Universe The universe is everything that is. The universe is comprised of billions of galaxies, which are comprised of billions of stars, which may have planets trapped in orbit around them. Each star, whose gravity has captured planets around it is called a solar system.

3. The Milky Way Our solar system is located in the outer reaches of the Milky Way Galaxy, which is a spiral galaxy. The Milky Way Galaxy contains roughly 200 billion stars. Most of these stars are not visible from Earth. Almost everything that we can see in the sky belongs to the Milky Way Galaxy.

4. How big is the Universe?  A light year is about 6 trillion miles.  The brightest star in our night sky is Sirius. It is 8 light years away. Sirius is in our galaxy.  The Andromeda Galaxy is about 2.5 million light years away.

5. Our Solar System Planet: one of the 8 celestial bodies revolving around the sun. Planet requirements: revolve around the sun, be spherical and have a clear orbital path.

6. Revolution: The movement of a planet around the sun. Rotation: The spinning motion of a planet about its axis.

7. We ______ around the sun. When we orbit or revolve around the sun, we do not travel in a perfect circle. Earth revolves around the sun in an elliptical path. An ellipse is kind of like a squashed circle. revolve

9. Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune

10. Pluto is now considered a dwarf planet. It lost its ‘planet’ status because it had NOT cleared its orbital neighborhood.

11. How can we remember the order of the 8 planets? By remembering this sentence: My Very Eager Mother Just Served Us Nachos!

12. Our 8 Planets MyMercury VeryVenus EducatedEarth MotherMars JustJupiter ServedSaturn UsUranus NachosNeptune

13. What keeps the planets and other objects in our solar system in orbit? gravity & inertia 1.How are the inner & outer planets different? 2.How are they alike? 3.Which planet has the most moons? Why? Inner planets – small and rocky/terrestrial Outer planets - large and gaseous All have mass, all orbit the sun Jupiter, as it has the largest mass

14. An asteroid belt separates the inner and outer planets.

15. What are some other things in our solar system besides the sun and the planets?

16. Asteroid Asteroid: a body composed of rock and/or metal which orbits the Sun.

17. It is believed that an asteroid hit our planet millions of years ago and caused the extinction of the dinosaurs.

18. Meteoroid, Meteor, Meteorite

19. Meteoroid Meteroid: A chunk of rock (that is smaller than an asteroid) in space.

20. Meteor Meteor: chunk of rock/dust (meteoroid) traveling through our atmosphere.

21. A meteor is a bright streak of light that appears briefly in the sky. Air friction heats the meteoroid so that it glows. They usually burn up when entering the atmosphere due to air friction.

22. Meteorite Meteorite: A meteoroid that has hit the Earth’s surface.

23. Comet Astronomers believe that comets are leftover debris from a collection of gas, ice, rocks, and dust. Comet: a ball of ice and dust whose orbit is a long, narrow ellipse.

24. Hubble Telescope The Hubble Telescope was sent into space in 1990 to study the universe. Hubble Telescope Facts: NASA named the world's first space- based optical telescope after American astronomer Edwin P. Hubble (1889—1953) Length: 43.5 ft (13.2 m) Weight: 24,500 lb (11,110 kg) Cost at Launch: $1.5 billion Date Launched: 4/20/90 Time to complete one orbit: 97 minutes Speed: 17,500 mph Go to http://hubblesite.org/ to see images captured by the Hubble!http://hubblesite.org/