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29 terms

Astronomy Vocabulary

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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.
Ellipse
An elongated circl or oval shape. The shape of the planets orbits
Inertia
The tendency of a moving object to continue in a straight line or a stationary object to remain in place
Gravity
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
Core
The center of something
Photosphere
The inner layer of the sun. Seen when you look at image of the sun.
Chromosphere
The middle layer of the sun. Seen during a solar eclipse. It is the reddish glow
Corona
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
Sunspots
Areas of gas on the sun that are cooler than the gasses around them
Prominences
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
Rotation
The spinning motion of planets about its axis
Revolution
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
Comets
Large chunks of ice and dust whose orbits can be very long, narrow ellipses
Asteroid
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
Meteoroid
A chunk of rock or dust in space
Meteor
The streak of light in the sky when a meteoroid is coming to Earth
Meteorites
Meteoroids that pass through the atmosphere and hit Earth's surface
Satellite
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

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