Solar System

Ellipse

A elongated circle, or oval shape, the shape of the planets orbit.l

Astronomical Unit

A unit of length used for distances within the solar system; 1 AU = the average distance from the Earth to the Sun

Inner Planets

Planets that are: rocky, high densities, revolve around the sun quickly, thin atmospheres, relatively warm, rotate on axis slowly, few if any moons, terrestrial, no rings

Outer Planets

Planets that are: rotate on own axis quickly, revolve around the sun slowly, low densities, huge gas giants, thick gaseous atmospheres, cold, all have rings, all have MANY moons

Uranus

Seventh planet from the Sun; is large and gaseous with thin, dark rings and rotates tilted on its side; over 27 moons

Dwarf planets

Small round bodies that orbit the sun but have not cleared the area around their orbits of other orbiting bodies;Pluto, Eris, Ceres

What keeps any planet from flying off into outer space?

The gravitational pull of the sun

Revolution

The movement of an object around another object (a year)

Galileo Galilei

This scientist proved Copernicus' theory was correct that the sun was the center of the solar system and developed the modern experimental method. With his telescope he saw that Venus had phases similar to our moon's phases, and he saw the four large moons of Jupiter orbiting Jupiter and not Earth!

Star

a celestial body of hot gases that radiates energy derived from nuclear reactions in the core

Meteroid

a chunk of rock or dust that moves through outer space

Meteorite

a meteoroid that does not completely burn up in the atmosphere and strikes the surface of a moon or planet

Meteor

a streak of light in the sky that happens when a meteoroid hits the earth's atmosphere and air friction causes the meteoroid to melt or vaporize or explode

Gravitational Force

an attractive force that acts between any two objects

Planet

any of the celestial bodies that revolves a star and has large enough to have become rounded by its own gravity, and has cleared its path in orbit

Mars

has two moons, reddish in color due to iron oxide (rust), the "Red" planet

Comets

large clumps of ice, dust and frozen gases that travel around the Sun in long elliptical orbits; only have a tail when they are close to the sun; tail always points away from the sun

Neptune

large, gaseous planet with rings, dark-colored storms, and over 13 moons; has a distinctive blue-green color; 8th planet from our sun

Natural Satellites

moons

Asteroids

rocky metallic objects that orbit the sun but are too small to be considered planets

Venus

second planet from the Sun; the hottest planet in our solar system, similar to Earth in mass and size; Earth's "Evil Twin," has a thick atmosphere of carbon dioxide gas and a surface with craters and over 1,500 volcanoes

Mercury

smallest planet, only other inner planet with magnetic field (beside Earth), The "Incredible Shrinking" planet

Solar System

sun, planets, and all the other objects that revolve around the sun due to the sun's gravitational pull

Heliocentric Model

the accepted model of our solar system with the sun in the center

Retrograde rotation

the clockwise spin of a planet or moon as seen from above the planet's or moon's north pole; also causes day and night to occur

Rotation

the counter-clockwise spinning of a planet or moon; example: the Earth's spinning on its imaginary axis, which takes about 24 hours to complete and causes day and night to occur

Geocentric Model

the early, incorrect model of our solar system with the earth in the center

Jupiter

the largest planet and the 5th from the sun; over 63 moons

Orbit

the path of an object as it revolves around another object in space; usually the shape of an ellipse

Saturn

the planet that could float on water, due to the fact it is primarily hydrogen; over 60 moons and many rings

Asteroid Belt

the region of the solar system between the orbits of Mars and Jupiter, where many asteroids are found

Inertia

the tendency of an object to resist any change in its motion

Earth

third planet from the sun; has an atmosphere that protects life and surface temperatures that allow water to exist as a solid, liquid, and gas; the "Water Planet"