Solar System
density
1. A measurement that is equal to the amount of mass per unit of volume. 2. How heavy an object is relative to its size; the ratio of mass to volume.
telescope
1. An instrument that makes distant objects seem larger. 2. A magnifier of images of distant objects.
elliptical
1. Containing or characterized by ellipsis. 2. Rounded like an egg.
Mars
1. In Roman mythology, this planet is named after the god of war. 2. This planet is also known as the Red Planet. 3. The 4th planet from the sun.
Venus
1. In Roman mythology, this planet is named after the goddess of love and beauty. 2. The brightest and sixth largest planet in the Solar System. 3. This planet is the second planet from the sun, having a diameter of about 7,500 miles and a dense, cloudy atmosphere.
satellite
1. Man-made equipment that orbits around the earth or the moon. 2. Any celestial body orbiting around a planet or star.
mass
1. The amount of physical matter that an object contains. 2. The property of a body that causes it to have weight in a gravitational field.
gravity
1. The force by which a planet or other body tends to draw objects toward its center. 2. A force that pulls objects towards each other. 3. The moon has less gravity than the Earth.
Jupiter
1. The largest planet in the Solar System. 2. Four of the moons of this planet are Io, Europa, Ganymede, and Callisto. 3. The Great Red Spot is a distinct feature that can be seen on this planet. 4. The fifth planet from the sun in the solar system. This is the largest planet in the Solar System.
Neptune
1. The use of mathematics facilitated the discovery of this planet. 2. This planet has the strongest winds in the Solar System. 3. A giant planet with a ring of ice particles; the 8th planet from the sun.
greenhouse effect
1. The warming of an atmosphere that is the result of gases such as carbon dioxide which prevent the sun's heat from escaping. 2. when the sun's heat is trapped in the atmosphere, causing a rise in temperature
Earth
1. This is the third planet from the sun. 2. The densest planet in the Solar System. 3. The only planet where life is known to exist.
Saturn
1. This planet has two bright prominent rings. 2. This planet has many moons, including Titan, Dione, Tethys, and Mimas. 3. This planet is the least dense of any planet. 4. The sixth planet from the sun in the solar system. This planet has two bright prominent rings.
Mercury
1. This planet is named after the messenger of the gods (from Roman mythology). 2. The temperature on this planet ranges from 90 K to 700 K, but it is not the hottest planet in the Solar System. 3. The planet closest to the sun and the fastest moving planet in the Solar System.
Uranus
1. This planet's axis is almost parallel to the ecliptic. 2. This planet has eleven known rings, all of which are very faint. 3. This planet's blue color is the result of methane gas in the atmosphere.
crater
A bowl-shaped hole on the surface of a planet or moon that was caused by the impact of a meteorite.
asteroid belt
A concentration of small celestial bodies between Mars and Jupiter.
irregular
A galaxy that does not have a regular shape, like a spiral or an elliptical galaxy
carbon dioxide
A gas with no color or odor that is a mixture of carbon and oxygen.
constellation
A group of stars that are named after the shape it resembles.
meteors
A piece of rock or metal from space that enters the earth's atmosphere at high speed and burns up.
comet
A relatively small, icy celestial body with a long tail of light that revolves around the sun.
sun
A typical star that is the source of light and heat for the planets in the solar system.
astronomical unit
A unit of length equal to the average distance from Earth to the sun (93 million miles).
Milky Way
A very large group of stars and planets that include the Sun and its solar system.
helium
A very light colorless element that is one of the six inert gasses; the most difficult gas to liquefy
axis
An imaginary line through the middle of a body or planet, through which that object spins.
spiral
Any galaxies consisting of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge.
asteroid
Any of thousands of celestial bodies with diameters between one and five hundred miles that revolve around the sun in orbits located mostly between those of Jupiter and Mars.
moons
Any planet's natural satellite.
outer planets
Group of planets: Jupiter, Saturn, Uranus, and Neptune.
revolution
One complete circular movement made by one object around another object.
meteorites
Pieces of rock or metal that have reached the Earth from outer space.
inner planet
Planet group including Mercury, Venus, Earth and Mars
rings
Saturn has two of these that are very bright.
space probe
Space vehicle carrying sophisticated instrumentation but no crew, designed to explore various aspects of the solar system.
aphlion
That point of a planet's or comet's orbit which is most distant from the sun.
rotation
The act of turning on, or around, an axis. On Earth, this is equal to 23 hours, 56 minutes, and 4 seconds.
astronomy
The branch of science that studies stars, planets, and everything else beyond the atmosphere of the earth.
orbit
The curved path in which a planet, satellite, or spacecraft revolves around another body.
temperature
The degree of heat or cold of a body or an environment.
atmosphere
The mixture of gases that surrounds a planet.
planet
The nine major celestial bodies that orbits the sun.
corona
The outer atmosphere of a star.
perihelion
The point in the orbit of a planet or other body at which it comes closest to the sun.
erosion
The process by which material is worn away by forces such as glaciers, wind, and waves.
solar system
The sun and the celestial bodies that orbit the sun, including planets, satellites, asteroids, comets, dust, and gas.
barred spiral
These galaxies are relatively common, with up to two-thirds of all spiral galaxies contain a bar. The current hypothesis is that the bar structure acts as a type of stellar nursery, fueling star birth at their centers.
core
the innermost layer of the sun.
