Objects in the Solar System
Our Solar System consists of a central star (the Sun), the nine planets orbiting the sun, moons, asteroids, comets, meteors, interplanetary gas, dust, and all the “space” in between them. The nine planets of the Solar System are named for Greek and Roman Gods and Goddesses.
Inner and Outer Planets:
Inner Planets:
Mercury Venus Earth Mars |
Outer Planets:
Jupiter Saturn Uranus Neptune Pluto |
The Relative Size of the Planets in the Solar System
The sun’s energy comes from nuclear fusion (where hydrogen is converted to helium) within its core. This energy is released from the sun in the form of heat and light. Remember: Stars produce light. Planets reflect light. A star’s temperature determines its “color.” The coldest stars are red. The hottest stars are blue. |
The 9 Planets of the Solar System
Characteristics of Small Rocky Planets
- They are made up mostly of rock and metal.
- They are very heavy.
- They move slowly in space.
- They have no rings and few moons (if any).
- They have a diameter of less than 13,000 km.
Mercury
Mercury has a revolution period of 88 days. Mercury has extreme temperature fluctuations, ranging from 800°F (daytime) to -270°F (nighttime). Even though it is the closest planet to the sun, Scientists believe there is ICE on Mercury! The ice is protected from the sun’s heat by crater shadows. |
Mercury |
Venus
Earth
Earth’s Moon
Mars
Pluto
Characteristics of Gas Giants
- They are made up mostly of gases (primarily hydrogen & helium).
- They are very light for their size.
- They move quickly in space.
- They have rings and many moons.
- They have a diameter of less than 48,000 km
Jupiter
Saturn
Saturn is composed almost entirely of hydrogen and helium. Saturn has many rings made of ice. Saturn’s rings are very wide. They extend outward to about 260,000 miles from the surface but are less than 1 mile thick. Saturn has 18 known moons, some of which orbit inside the rings! It takes Saturn about 30 years to orbit the sun.
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Saturn |
Uranus
Neptune
The path of one object in space around another object is called its orbit.
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