1. Astronomy: Solar System

2. The Solar System
Consists of the sun, 8 planets, and their moons, and several kinds of smaller objects that revolve around the sun

3. Our Solar System’s Only Star:
Only one star

4. The Sun: The Sun is the only star in the solar system
The sun's light takes about 8 minutes to reach the Earth after it has been emitted from the sun's surface.
About 109x the size of Earth

5. Our sun in comparison to other stars:
The Sun is a medium sized star
There are giant stars that are 100x larger than the sun

6. What is a planet? 3 Criteria:
1) An object that orbits a star 2) Large enough to become rounded by its own gravity 3) Able to clear its own orbit of objects, such as asteroids, meteoroids, other space junk!

7. The Solar System
The 4 inner planets (Mercury, Venus, Earth, and Mars) are called terrestrial planets
The outer planets (Jupiter, Saturn, Uranus, and Neptune) are called gas giants

8. Jupiter Saturn Relative Sizes of the planets: Earth Neptune Uranus
On your notes, put the planets in order from largest to smallest
Jupiter
Saturn
Uranus
Neptune
Earth
Mercury
Venus
Mars

9. Relative Sizes of the planets:
Jupiter
Saturn
Uranus
Neptune
Earth
Venus
Mars
Mercury

10. Actual Distance from Sun (km)
Planet
Actual Distance from Sun (km)
Mercury
57,900,000
Venus
108,200,000
Earth
149,600,000
Earth’s Moon
(Distance from Earth)
384,403
Mars
228,000,000
Jupiter
778,400,000
Saturn
1,426,700,000
Uranus
2,866,900,000
Neptune
4,486,100,000
Relative Distances of the planets:

11. The Earth
Earth is the third planet from the Sun 
Is the largest of the terrestrial planets

12. The Moon Earth’s only natural satellite
The Moon is in synchronous rotation with Earth (the same side is always facing the Earth)

13. The Moon
Size: 3,476 km in diameter (a little less than the distance across the United States)
Distance from Earth: 384,403 km
(110x the distance across the United States)

14. The Other planets also have moons:
Number of moons
Jupiter
60+
Saturn
31+
Uranus
25+
Neptune
13+

15. What’s with Pluto? 1. The object must be in orbit around the Sun.
Well, Pluto does that!
2. A "planet" has to be big enough that gravity squeezes it into a round shape.
Well, Pluto does that.
3. A planet must be big enough that it's gravity removes other objects that occupy the same orbit.
But Pluto does not meet this criterion.

16. Poor Pluto…
So, Pluto is considered
to be a DWARF PLANET

17. A name given for Dwarf planets (like Pluto) beyond Neptune
Plutoids
A name given for Dwarf planets (like Pluto) beyond Neptune

18. Have elliptical orbits
Asteroids
Rocky objects that are too small (1-100 km in diameter) and too numerous to be considered planets
They revolve around the sun in the asteroid belt (between the orbits of Mars and Jupiter)
Have elliptical orbits

19. Loose collections of ice, dust, and rocky particles
Comets
Loose collections of ice, dust, and rocky particles
Revolve around the sun in a very long, narrow elliptical orbit
Most comets are found in the Kuiper belt (extends beyond Neptune’s orbit) or the Oort cloud
Main parts: nucleus, coma, and tail

20. Meteoroid
Chunk of rock or dust in space
Come from comets or asteroids

21. Meteors
When a meteoroid enters Earth’s atmosphere, friction with the air creates heat and produces a streak of light in the sky called a meteor

22. Meteorite
If a meteoroid does not burn up completely, it passes through the atmosphere and hits the Earth’s surface and is called a meteorite

24. Put the following space objects in order from LARGEST to SMALLEST:
Planet
Asteroid
Star
Moon