1. EXPLORING
SPACE
EXPLORING SPACE

2. THE SOLAR SYSTEM

3. The solar system
Our Solar System is made up of the sun and everything that orbits the sun. Planets, their moons, asteroids, comets, dwarf planets.

4. The Planets
Our solar system contains 8 planets. They can be divided into the solid inner planets and the outer planets which are gas planets. They do not line up as shown in the picture below. It is possible for them to roughly line up once in millions of years.
The solid planets are Mercury, Venus, Earth and Mars. They are made up of iron and rock. The outer planets are Jupiter, Saturn, Uranus and Neptune. They have a core surrounded by gases like hydrogen and helium. They are known as the gas giants because they are so much larger than the inner planets. All the planets orbit the sun, but at different speeds. This picture is incorrect because they don’t orbit in a straight line.

5. The Sun
The sun is a star. It is a gigantic ball of exploding hydrogen and helium gas. The sun is so large, more than a million Earths could fit inside it. Everything in the solar system gets its heat and light from the sun. The sun is also the center of our solar system. The sun’s gravitational pull creates a pulling force that pulls everything within 3,750 million miles toward it. Everything in the solar system orbits around the sun.

6. Different planets revolve around the sun at different speeds
Different planets revolve around the sun at different speeds. It takes Jupiter almost 12 Earth years to revolve around the sun. It only takes Mercury about 88 earth days to revolve around the sun. So that means a year on Jupiter is 12 Earth years, and a year on Mercury is 88 Earth days.

7. The Earth takes 365. 25 days to orbit or REVOLVE around the sun
The Earth takes days to orbit or REVOLVE around the sun. One revolution around the sun is called a year. Every four years we add a 29th day to February to adjust for the 1/4th of a day each year.

8. The Earth rotates around one full
time every 23 hours and 56 minutes. We call this a day.

9. Asteroids:
Asteroids are large chunks of rock, or rock and metal that orbit the sun. Most asteroids are found in the asteroid belt between Mars and Jupiter.

10. Comets
Comets are large chunks of dirty ice that orbit the sun. As the sun’s gravity pulls them closer to the sun, the ice begins to melt. The tail you see is really water vapor from the melting ice.

11. Meteoroids
Meteoroids are small pieces of rock and metal which orbit the sun. When they are caught by Earth’s gravity and pulled into Earth’s atmosphere, the friction between the meteoroid and the atmosphere causes them to burn up. We call burning meteoroids meteors or falling stars.

12. Star or Planet?
A star is a burning ball of gas that gives off light and heat. A planet is made up of iron, rock or gases and does not make its own light or heat. Planets have to get light and heat from stars.

13. Mercury is 36 million miles from the sun and its high temperature is about 800 degrees Fahrenheit. Neptune is about 2,800 million miles from the sun and the high temperature on Neptune is around -330 degrees Fahrenheit. The farther a planet is from the sun, the colder its temperature.

14. Solar Eclipse
A solar eclipse occurs when the moon moves between the Earth and the Sun. The moon temporarily blocks out our view of the sun. During a total eclipse it becomes very dark outside and you can see rays of sunlight
radiating out from behind the moon.

16. Lunar Eclipse
A lunar eclipse occurs when the Earth moves between the sun and the moon and the Earth’s shadow falls on the moon.

18. THE MILKY WAY
The Milky Way is the galaxy we live in. Our galaxy is a huge collection of about 100 billion stars and everything that orbits the stars. Our sun is found about 28,000 *light years from the center of the Milky Way Galaxy, and since we are on Earth, and the Earth orbits the sun, that means we are found about 28,000 light years from the center of the Milky Way galaxy.
* A light year is the distance that light travels in a year, about 5.88 million million miles.

19. THE MILKY WAY GALAXY