The Solar System

Front 1

Geocentric model

Back 1

a superseded description of the universe with the Earth at the center.

Front 2

Heliocentric model

Back 2

system is one in which the planets revolve around a fixed sun.

Front 3

Moon

Back 3

natural satellite of the earth, visible (chiefly at night) by reflected light from the sun.

Front 4

Nebula

Back 4

cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter.

Front 5

Nebular Hypothesis

Back 5

theory that the solar and stellar systems were developed from a primeval nebula.

Front 6

Solar System

Back 6

collection of eight planets and their moons in orbit around the sun, together with smaller bodies in the form of asteroids, meteoroids, and comets.

Front 7

Day

Back 7

period of twenty-four hours as a unit of time, reckoned from one midnight to the next, corresponding to a rotation of the earth on its axis.

Front 8

Inner Planets

Back 8

planet whose orbit lies within the asteroid belt, i.e., Mercury, Venus, Earth, or Mars.

Front 9

Terrestrial Plants

Back 9

plant that grows on or in or from land

Front 10

Year

Back 10

the period of 365 days (or 366 days in leap years) starting from the first of January, used for reckoning time in ordinary affairs.

Front 11

Galilean moons

Back 11

the four largest moons of Jupiter—Io, Europa, Ganymede, and Callisto.

Front 12

Gas Giants

Back 12

large planet of relatively low density consisting predominantly of hydrogen and helium, such as Jupiter, Saturn, Uranus, or Neptune.

Front 13

Great Red Spot

Back 13

a giant, spinning storm in Jupiter's atmosphere

Front 14

Outer Planets

Back 14

planet whose orbit lies outside the asteroid belt, i.e., Jupiter, Saturn, Uranus, or Neptune.

Front 15

Planetary Rings

Back 15

A ring system is a disc or ring orbiting an astronomical object that is composed of solid material such as dust and moonlets, and is a common component of satellite systems around giant planets.

Front 16

Asteroid

Back 16

small rocky body orbiting the sun.

Front 17

Asteroid Belt

Back 17

circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter.

Front 18

Comet

Back 18

celestial object consisting of a nucleus of ice and dust and, when near the sun, a “tail” of gas and dust particles pointing away from the sun.

Front 19

Dwarf Planet

Back 19

celestial body resembling a small planet but lacking certain technical criteria that are required for it to be classed as such.

Front 20

Kuiper Belt

Back 20

region of the solar system beyond the orbit of Neptune, believed to contain many comets, asteroids, and other small bodies made largely of ice.

Front 21

Meteor

Back 21

small body of matter from outer space that enters the earth's atmosphere, becoming incandescent as a result of friction and appearing as a streak of light.

Front 22

Meteor Shower

Back 22

number of meteors that appear to radiate from one point in the sky at a particular date each year, due to the earth's regularly passing through a field of particles at that position in its orbit.

Front 23

Meteoroid

Back 23

small body moving in the solar system that would become a meteor if it entered the earth's atmosphere.

Front 24

Mercury

Back 24

chemical element of atomic number 80, a heavy silvery-white metal that is liquid at ordinary temperatures.

Front 25

Venus

Back 25

Roman goddess of beauty and love, or the second planet from the sun.