1. Celestial Objects 6 th Grade Science

2. Sun The Sun is a star at the center of our solar system. The Sun is very dense and made up of extremely hot gases (Hydrogen and Helium). The Sun also rotates on an axis. The Sun is a star at the center of our solar system. The Sun is very dense and made up of extremely hot gases (Hydrogen and Helium). The Sun also rotates on an axis.

3. The Inner Planets

4. Characteristics of Inner Planets Any of the rocky terrestrial planets of Mercury, Venus, Earth, and Mars. These planets are rocky with metal cores and are mostly solid with minerals similar to those on Earth. Each planets rotates on an axis.

5. Outer Planets

6. Characteristics of Outer Planets Any of the gaseous planets of Jupiter, Saturn, Uranus, and Neptune. The outer planets (Gas Giants) have more moons than the inner planets because they are larger and have more gravitational pull. Any of the gaseous planets of Jupiter, Saturn, Uranus, and Neptune. The outer planets (Gas Giants) have more moons than the inner planets because they are larger and have more gravitational pull.

7. Galilean Moons The Galilean moons (Io, Europa, Ganymede, and Callisto) are the four largest and brightest moons (satellites) of Jupiter discovered by Galileo in the 1600’s. The Galilean moons (Io, Europa, Ganymede, and Callisto) are the four largest and brightest moons (satellites) of Jupiter discovered by Galileo in the 1600’s.

8. Characteristics of Galilean Moons Io – large, rocky, volcanically active moon Io – large, rocky, volcanically active moon Europa – large, dense, icy moon Europa – large, dense, icy moon Ganymede – large, icy, outer moon with many craters Ganymede – large, icy, outer moon with many craters Callisto – large, icy, dark-colored, low density Callisto – large, icy, dark-colored, low density

9. Meteors A meteor is a meteoroid (a natural chunk or rock or dust) that has entered the Earth's atmosphere, usually making a fiery trail as it falls. It is sometimes called a shooting star. Most burn up before hitting the Earth. A meteor is a meteoroid (a natural chunk or rock or dust) that has entered the Earth's atmosphere, usually making a fiery trail as it falls. It is sometimes called a shooting star. Most burn up before hitting the Earth.

10. Asteroids An asteroid is a large rocky object or very small planet (planetoid). An asteroid is a large rocky object or very small planet (planetoid).

11. When asteroids and planets meet up… Meteors!! Small rocks (meteoroids) are constantly shooting around in outer space (smaller than asteroids—we’re talking sand to boulder sized). These objects are pulled in by the gravity of planets and moons and streak through the object’s atmosphere, becoming a meteor, and if it doesn’t burn up entirely and actually strikes the surface, is called a meteorite. Are these meteoroids, meteors, or meteorites?

12. Comets A chunk of frozen gases, ice, and rocky debris that orbits the Sun. Has a tail of gas and dust. A chunk of frozen gases, ice, and rocky debris that orbits the Sun. Has a tail of gas and dust.

13. Orbital Path The curved path, usually elliptical, described by a planet, satellite, or spaceship around a celestial body. The force that controls this motion is gravity. The curved path, usually elliptical, described by a planet, satellite, or spaceship around a celestial body. The force that controls this motion is gravity.

14. Rotation Spinning of a planet, Spinning of a planet, moon, sun, or other object on its axis. It takes the Earth one full day (24 hours) to make a complete rotation.

15. Revolution One orbit of an object in space around another object in space such as the moon around the Earth.

16. Orbit The path an object in space follows as it revolves around another object, such as Earth around the sun or a satellite around Earth The path an object in space follows as it revolves around another object, such as Earth around the sun or a satellite around Earth

17. Gravity All celestial bodies in our solar system revolve around the Sun and are held together by gravity. Gravity is a physical force that pulls objects together. The more mass you have, the stronger the gravitational force you exude. All celestial bodies in our solar system revolve around the Sun and are held together by gravity. Gravity is a physical force that pulls objects together. The more mass you have, the stronger the gravitational force you exude.