Science: Astronomy


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Moon Satellites that orbit around planets.
Asteroids Small Rocks and Metal Bodies that orbit around the sun
Comets Large chunks of ice, dust and rock that orbit the sun (size: 100 m-400 m)
Planets Large Celestial Objects that orbit around the sun. (8 in our solar system) largest in its orbit
Astronomy The study of everything that is beyond Earth
Universe Everything that exists. Made up of billions of galaxies.
Celestial Objects Anything we see in space
Stars Massive bodies composed of hot gasses. Radiate large amounts of energy.
Outer Planet Jupiter, Saturn, Uranus, Neptune. Made up of gas
Meteors Bright streaks of light associated with meteoroids entering earths atmosphere
Meteoroid A small piece of metal or rock
Meteorites A meteor that survives its passage through the earths atmosphere such that part of it strikes the ground.
Constellations A group of stars that from the earth resemble a recognizable form
Galaxies A collection of hundreds of billion of stars held together by gravity
Luminous Generates it's own light
Non-luminous Does not generate its own light
Inner Planets Mercury, Venus, Earth and Mars. All terrestrial planets and made up of rock.
Dwarf Planet A celestial object that is no longer the largest object in its orbit
Core 15 000 000 Degrees C. Fusion occurs here.
Fusion Occurs in the core. Hydrogen atoms collide and join together releasing energy in the form of light and heat.
Radiative Zone First layer that surrounds the core. Energy released from the core can take up to a million years to pass through te radiative zone
Convection Zone Layer after radiative zone. Hotter substances rise and colder substances fall.
Photosphere Sun's surface. 5 500 degrees Celsius. Light and other types of radiation escape here.
Chromosphere Inner Atmosphere of sun. About 65000 degrees Celsius.
Corona Outer Atmosphere of sun. Gleaming whit, halo like. Extends millions of kilometers into space.
Sunspots Dark Spots appearing on the suns surface that are cooler than the area surrounding them.
Solar Flare Large Quantities of gas and charged particles are released. Produced by rapidly changing magnetic fields around sunspots. Only last a short period of time
Solar Prominences Slow, low energy ejections of gas that travels through the corona.
Astronomical Unit Average distance between sun and earth. Approximately 150 000 000 km.
Rotation Earth makes one full rotation everyday. Goes west to east.
Revolution Earth revolves around the sun on an elliptical path. Orbits the sun once every 365.25 days.
Seasonal Change Caused by the earths change in tilt. (ex. When the northern hemisphere is tilted towards the sun it is summer in this hemisphere.
Why do we only see one side of the moon? The moon and the earth are in synchronized orbits. Only half the moon is luminaries by the sun at all times.
Phases of the moon New moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, waning crescent.
Eclipse Caused the the position of one celestial body blocking/darkening another
Solar Eclipse The sun is blocked from earth by the moon
Lunar Eclipse When the earth is positioned between the sun and the moon. Causing a shadow on the moon.
Elliptic The path taken by the sun. As it appears to us on earth.
Planetary Motion The orbit a planet takes around the sun.
Retrograde Motion When a planet appears to change its direction/path in the sky relative to background stars. They slow, reverse and the loop across the sky.
Polaris North Star. If earths axis from north pole extends into space it would pass very close to this star.
Azimuth The distance measured north along the horizon to a point directly below a celestial object. North is 0, East is 90, South is 180, West is 270
Altitude The angular height of a celestial object measured from the horizon
Light Year The distance that light travels in a year. 9.46 x 10^12 km.
Star Brightness Depends on luminosity, apparent magnitude and absolute magnitude
Luminosity Total amount of energy produced by a star per second. Sun-1 Sirius-22
Apparent Magnitude Brightness of a star as seen from earth, smaller numbers indicate more apparent brightness.
Absolute Magnitude Indicates apparent magnitude of a star if viewed from 33 light years away.
Star Color and temperature from cold to hot Red, orange, yellow, white, blue.