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Geocentric System

Earth is at the center of the revolving planets

Heliocentric system

Earth and the other planets revolve around the sun

Solar System

The sun is at the center of a system of planets.


An elongated circl or oval shape. The shape of the planets orbits


The tendency of a moving object to continue in a straight line or a stationary object to remain in place


The force that pulls all objects towards each other

Nuclear Fusion

The process of hydrogen atoms joining together to form helium. The sun's energy comes from nuclear fusion


The center of something


The inner layer of the sun. Seen when you look at image of the sun.


The middle layer of the sun. Seen during a solar eclipse. It is the reddish glow


The outer layer of the sun. Seen during a total solar eclipse. Looks like a white halo around the sun

Solar Wind

A stream of electrically charged particles sent out from the corona


Areas of gas on the sun that are cooler than the gasses around them


Reddish loops of gas that link different parts of sunspot regions

Solar Flares

Occur when hydrogen gas explode from the sun out into space

Terrestrial Planets

The 4 planets closest to the sun. They are small and have rocky surfaces. Mercury, Venus, Earth and Mars


The spinning motion of planets about its axis


Movement of a planet around the sun

Retrograde Rotation

When a planet rotates from east to west, the opposite direction of most planets. Venus and Uranus have retrograde rotations

Greenhouse Effect

When the atmosphere of a planet traps heat. Example, Venus or Earth

Gas Giants

The 4 planets farthest from the sun. Do not have solid surfaces. Jupiter, Saturn, Uranus and Neptune


Large chunks of ice and dust whose orbits can be very long, narrow ellipses


More than 300 in the solar system. To small and numerous to be planets. Found in a belt called the asteroid belt between Mars and Jupiter

Asteroid Belt

Part of the solar system in between Mars and Jupiter where most asteroids are found


A chunk of rock or dust in space


The streak of light in the sky when a meteoroid is coming to Earth


Meteoroids that pass through the atmosphere and hit Earth's surface


A natural or artificial object that revolves around an object in space. Example, the moon is a natural satellite

Geosychronous Orbits

When a satellite revolves around the Earth at the same rate that Earth rotates

Flickr Creative Commons Images

Some images used in this set are licensed under the Creative Commons through Click to see the original works with their full license.

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