Astronomy

universe

all of space and everything in it

spiral galaxy

galaxy with a central bulge and arms that stretch outward

irregular galaxy

galaxy with no definite shape

geocentric

theory that the Earth was at the center of the solar system

ellipse

shape of a planet's orbit

terrestrial

name given to the four small, rocky inner planets

asteroid

object made of rock and metal that orbits the Sun in the area between Mars & Jupiter

comet

Object made of ice & dust that orbits the Sun in long, narrow ellipses. Usually gets a tail as it approaches the Sun

meteor

rocky body that burns up as it passes through Earth's atmopshere

nebula

cloud of dust and gas

protostar

first star that forms in a nebula

supernova

explosion of a supergiant star

neutron star

small, leftover remains of a star after a supergiant explosion

pulsar

neutron star that emits electromagnetic radiation

sunspot

dark, cooler regions on the Sun

prominence

loop of gas that connects sunspots

big bang

theory that an explosion created the entire universe ~13 billion years ago

galaxy

collection of millions or billions of stars, dust, and gas held together by gravity

elliptical galaxy

galaxy shaped like a ball and contains mostly old stars

light-year

distance measurement for how far light travels in one year

heliocentric

theory that the Sun is at the center of the solar system

inertia

concept of an object in motion will stay in motion (planets), while an object at rest will stay at rest until a force acts to change it

gas giants

names given to the large, gassy outer planets

asteroid belt

region between Mars & Jupiter that contains rocky bodies too small to be considered planets

meteoroid

Small, rocky/metal object floating around in space, or orbiting the Sun in the asteroid belt. Object may have broken off an asteroid.

meteorite

small, rocky/metal object that has hit Earth's surface

nuclear fusion

Process when hydrogen is converted into helium, producing heat and light. Sun's energy is created this way.

giant star

a large star

black hole

occurs when a supergiant explodes and the gravity is so strong that it pulls everything inward - no heat or light can escape

white dwarf

small dense remains of a star after the outer layers have blown off into space

solar wind

Stream of electrically charged particles release from the Sun. Helps to create the aurora borealis.

solar flare

explosion of hydrogen gas on the Sun