ASTRONOMY EARTH AND SPACE SCIENCE

Earth

the third planet from the sun; an inner planet (inside the asteroid belt); only known habitable planet; 71% of surface covered with liquid water

Pluto

previously classified as the ninth planet from the sun; usually now classified as a minor planet or dwarf planet; has five moons

Makemake

a dwarf planet in the Kuiper belt

Dwarf Planet

a small planet not large enough to clear its orbit of debris

Example.

Pluto

Period (of a Comet)

the amount of time it takes for a comet to orbit the sun

Example.

Halley's Comet has a period of about 75 years

Meteor

a meteoroid that has entered Earth's atmosphere

Meteoroids

small bodies of debris from space which move into Earth's atmosphere and can then turn into meteors

Mars

the fourth planet from the sun; an inner planet (inside the asteroid belt); the "Red Planet"; home to Olympus Mons, the tallest mountain in the solar system;

Asteroid Belt

the region of space between Mars and Jupiter containing most of the solar system's asteroids

Solar System

a star, as well as the planets, satellites, asteroids, and all the other objects orbiting it, travelling together through space

Comet

a body made of ice and dust in the sun's orbit; contains a gas and dust "tail"

Example.

Halley's Comet

Jupiter

the fifth planet from the sun; an outer planet (outside the asteroid belt); largest planet; over twice as massive as all the other planets combined; has four large moons; about 90% hydrogen and 10% helium

Neptune

the eighth planet from the sun; an outer planet (outside the asteroid belt); methane in the atmosphere absorbs red light to make it appear blue; gives off over twice as much energy as it receives from the sun

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Celestial Bodies

a physical object in space which has observable characteristics

Example.

planet

Haumea

a dwarf planet with an orbit beyond Neptune

Planet

a body moving in orbit around a star; large enough to clear debris in its orbit; has enough gravity to make it round

Example.

Earth

Virgo Supercluster

a supercluster of galaxies that contains the Local Group and spans over 100 million light-years

Oort Cloud

a shell of comet bodies which orbit the sun

Nebula

a gas and dust cloud in space

Example.

Orion Nebula

Neutron Star

a small star with high density; made of closely packed neutrons

Example.

Crab Pulsar

Constellations

a star grouping which forms a pattern; we have ascribed images to the constellations

Example.

Orion

Saturn

the sixth planet from the sun; an outer planet (outside the asteroid belt); the least dense planet; has a complex ring system

Planetoids

bodies that orbit the sun that are smaller than planets and larger than asteroids

Example.

dwarf planets

Friction

the force, in the opposite direction of motion, between two objects moving over one another

Milky Way Galaxy

the spiral galaxy in which our solar system is located

Asteroids

small, rocky bodies in the sun's orbit

Example.

Ceres

Stars

a gaseous body which produces radiant energy through nuclear fusion reactions

Example.

the sun; Sirius

Small Solar System Bodies (SSSBs)

all small bodies in the solar system except planets, dwarf planets, and satellites; name was accepted in 2006

Example.

asteroids, comets, meteors, minor planets

Shooting Star

a streak of light in the night sky caused as a meteor burns up in the atmosphere

Black Hole

an object with gravity great enough that it does not allow radiation or matter to escape

Satellite

an object or body that orbits another object or body

Example.

Earth's moon

Moons

satellites which orbit planets

Example.

Phobos

Venus

the second planet from the sun; an inner planet (inside the asteroid belt); slightly smaller than Earth; similar density and chemical composition to Earth

Kuiper Belt

a flat disc of comets, asteroids, and other small icy objects that orbit the sun at a distance beyond Neptune

Uranus

the seventh planet from the sun; an outer planet (outside the asteroid belt); composed mostly of rock and ice; has 27 named moons

Minor Planets

synonym for planetoid, also includes large asteroids

Mercury

the first planet from the sun; an inner planet (inside the asteroid belt); slightly larger than Earth's moon; experiences extreme temperature variations; large iron core

Exoplanets

planets which orbit stars outside our own solar system

Example.

Proxima Centauri b

Local Group

a group of galaxies that contains the Milky Way galaxy and spans almost 10 million light-years

Galaxies

a system of stars and their systems held together by gravity

Example.

Milky Way Galaxy

Binary Stars

a two-star system; the stars rotate around a common point, or one star rotates around the other

Example.

Castor

Meteorite

what remains of a meteor after it hits the surface of the earth

Eris

the most massive and second largest dwarf planet in the solar system

Ceres

a dwarf planet located in the asteroid belt between Mars and Jupiter