When pulsars were first discovered, they were labeled LGM 1,2, and 3. The discoverer, Jocelyn Bell, an astronomer at Cambridge University in England, believed that the pulses were signals from intelligent life in outer space. LGM stands for "little green men." When many more Ec[000000]f[16]LFpulsars were discovered, it was realized that they were not signals from alien beings.
Ec[000000]f[16]LBAlbert EinsteinB
Famous scientist and physicist born in Germany in 1879. He is considered to be one of the most brilliant theoretical physicists of all time. His formula of E = mc2 (energy equals mass times the speed of light squared) and his theory of relativity were the basis for the use of atomic energy in our world. Einstein died in 1955.
Ec[000000]f[16]LBArielB
The brightest of the moons of Uranus.
Ec[000000]f[16]LBasteroidB
A small particle of matter that orbits the Sun in space between Mars and Jupiter. Asteroids range in size from as small as a basketball or soccer ball to as large as five hundred miles in diameter.
Ec[000000]f[16]LBasteroid beltB
An area between the orbits of Mars and Jupiter where thousands of asteroids are in orbit around the Sun.
Ec[000000]f[16]LBastronomerB
A scientist who studies astronomy or any of its modern sub-fields: astrophysics, cosmology, radio astronomy or any of the other specialties in space science.
Ec[000000]f[16]LBatmosphereB
The gaseous mass surrounding a planet.
Ec[000000]f[16]LBaurorasB
Luminous bands and streamers of light in the sky, caused by charged particles in the solar wind that strike the Earth, that usually appear in the polar regions.
Ec[000000]f[16]LBaxisB
The line around which Earth rotates. All the planets have an axis around which they rotate.
Ec[000000]f[16]LBCallistoB
One of the Galilean satellites of Jupiter. The name comes from Greek mythology where Callisto was a nymph changed into a bear by Jupiter and later placed into the heavens as the constellation Ursa Minor, the Little Dipper.
Ec[000000]f[16]LBCassini DivisionB
The gap between the two major rings of Saturn. It is named for its discoverer, Giovanni Cassini, an Italian-French astronomer of the seventeenth and eighteenth centuries.
Ec[000000]f[16]LBCeresB
Ceres is the largest known asteroid. It was discovered in 1801 by a Sicilian astronomer who thought he had discovered a new planet. He named it after the patron saint of Sicily and not after the Roman goddess of the Earth who bears the same name.
Ec[000000]f[16]LBCharonB
Pluto's only known satellite. It was named for the boatman who ferried the souls of the dead across the River Styx and into the underworld. Some astronomers think that Charon might be a twin planet to Pluto rather than its moon.
Ec[000000]f[16]LBChristian HuygensB
A Dutch physicist and astronomer of the seventeenth century who developed a refracting telescope with which he discovered the rings of Saturn.
Ec[000000]f[16]LBClyde TombaughB
An American astronomer of the twentieth century who is credited with discovering Pluto. Tombaugh worked at the Lowell Observatory, basing his research on the calculations of Percival Lowell, who had suggested the existence of Pluto in the early twentieth century. In 1930, Ec[000000]f[16]LFTombaugh found Pluto where Lowell had predicted it would be.
Ec[000000]f[16]LBcometB
A body in space that consists of a core of frozen rock and a tail of ice-covered particles of dust. Billions of comets exist in an area called the Oort Cloud, beyond the planet Pluto.
Ec[000000]f[16]LBcomet tailB
The luminous extension of a comet that can spread for millions of miles across the sky. It consists of dust that is illuminated by the charged particles of the solar wind. The tail always points away from the Sun.
Ec[000000]f[16]LBconstellationB
An easily identified group of stars that has been given a name, such as Ursa Major and Orion. There are eighty-eight constellations visible in the sky above Earth.
Ec[000000]f[16]LBCopernican systemB
The plan of the universe devised by Nicolaus Copernicus, a sixteenth-century Polish astronomer. Copernicus suggested that the Sun was the center of our solar system, and all planets and other celestial objects in the solar system revolved around the Sun. Copernicus's theories are the basis of modern astronomy.
Ec[000000]f[16]LBcoreB
The central section of a planet. Earth's core consists of metals such as iron and nickel and is partly liquid. The innermost core, however, is thought to be solid.
Ec[000000]f[16]LBcraterB
A large pit in the surface of Earth or any other planetary body. Large meteorites can create craters when they strike Earth.
Ec[000000]f[16]LBdensityB
The amount of something per unit measure.
Ec[000000]f[16]LBDianaB
Roman goddess of the moon who was also considered to be the great mother goddess of Earth.
Ec[000000]f[16]LBDioneB
A female Titan in Greek mythology and mother of Venus.
Ec[000000]f[16]LBearth grazersB
Asteroids that leave their orbit between Mars and Jupiter and fall towards Earth. They do not burn up in Earth's atmosphere nor do they fall to the surface of Earth. They pass on by and disappear.
Ec[000000]f[16]LBeclipseB
The passage of a satellite across the face of its planet which blocks out the light to the planet. On Earth, a solar eclipse occurs when the Moon passes in front of the Sun, blocking out its light. A lunar eclipse occurs when Earth passes between the Moon and the Sun, casting a Ec[000000]f[16]LFshadow on the Moon. Eclipses can occur with other planets but are not as dramatic as solar and lunar eclipses on Earth.
Ec[000000]f[16]LBEdwin HubbleB
Twentieth-century astronomer who formulated the principle of the expanding universe. The space telescope is named after him.
Ec[000000]f[16]LBellipseB
A curved shape like an oval or an egg with equal ends.
Ec[000000]f[16]LBEnceladusB
One of the smaller moons of Saturn with an extremely bright surface. Scientists believe the surface is composed of extremely pure ice without rocks or dust to darken it. The name comes from a giant monster in Roman mythology.
Ec[000000]f[16]LBequatorB
An imaginary line around the middle of the Earth drawn at equal distances between the north and south poles.
Ec[000000]f[16]LBEuropaB
The brightest of Jupiter's Galilean satellites, Europa was named for a beautiful woman in Roman mythology who was a lover of Jupiter and mother of some of his children.
Ec[000000]f[16]LBGalilean satellitesB
The four largest satellites of Jupiter that were discovered by Galileo Galilei in the seventeenth century. They are called the Galilean satellites in his honor.
Ec[000000]f[16]LBGalileo GalileiB
Galileo Galilei was an Italian physicist and astronomer who lived from 1564 to 1642. His major contribution to science was the invention of the telescope for studying the Moon and the planets.
Ec[000000]f[16]LBGanymedeB
Jupiter's largest moon and the largest satellite in the solar system. It is larger than the planet Mercury. In Greek mythology, Ganymede was the most beautiful mortal man. He was carried off to Olympus to live with the gods and goddesses.
Ec[000000]f[16]LBgas giantsB
The name given to the large outer planets in the solar system. They are Jupiter, Saturn, Uranus, and Neptune. They are called this because they were formed from the cooling gases of the nebula.
Ec[000000]f[16]LBgravitational forceB
The force of gravity from a planet or star or other body in space that pulls other bodies towards it. The gravitational pull of the Earth holds our Moon in orbit around us.
Ec[000000]f[16]LBgravityB
The attraction of a mass in space, such as a planet or satellite, that holds bodies on its surface. Earth's gravity causes items to fall to the ground.
Ec[000000]f[16]LBGreat Dark SpotB
A great storm on the surface of Neptune. It covers an area greater than the size of Earth.
Ec[000000]f[16]LBGreat Red SpotB
A never-ending storm on the surface of Jupiter. It is larger than Earth and has winds of 225 miles (360 kilometers) per hour.
Ec[000000]f[16]LBGreat White SpotB
A newly discovered storm on Saturn from pictures taken by the IVoyager 2I space probe. The storm covers the entire planet.
Ec[000000]f[16]LBheliumB
A light gas found on Earth and the Sun. It makes up about 24 percent of the Sun and is formed by the fusion of hydrogen. It also makes up parts of the gaseous outer planets.
Ec[000000]f[16]LBHubble Space TelescopeB
An orbiting space telescope launched by the United States in 1990. It was found to have a distorted lens that was later fixed in space. Discoveries made by the telescope have challenged many theories in astronomy and cosmology. New breakthroughs on the evolution of the Ec[000000]f[16]LFuniverse are being worked on right now from the data received from the telescope.
Ec[000000]f[16]LBhurricaneB
A tropical windstorm with winds exceeding 75 miles (120 kilometers) per hour. Hurricanes usually form in a low-pressure system over warm, tropical waters. Barometric pressure at the center of the storm drops rapidly and winds pick up speed as they rush towards the center. If Ec[000000]f[16]LFthe storm reaches shore, it can cause extensive damage.
Ec[000000]f[16]LBhydrogenB
A gas element which makes up about three-fourths of the Sun. The fusion of hydrogen into helium releases the great amount of heat that causes the Sun to glow. Hydrogen is also found in the outer layers of the gaseous planets.
Ec[000000]f[16]LBIapetusB
The second farthest of Saturn's known satellites. Astronomers believe it may be a ball of ice.
Ec[000000]f[16]LBice volcanoesB
Term given to the phenomenon occurring on Triton, a satellite of Neptune, which is the coldest object in space. The surface of Triton is covered with frozen nitrogen. When liquid nitrogen below the surface erupts, it forms "ice volcanoes" that throw clouds of icy nitrogen and methane into the thin atmosphere surrounding the moon.
Ec[000000]f[16]LBinfrared astronomical satelliteB
A special telescope sensitive to heat that is being used to search the sky for objects too cool to glow by their own heat.
Ec[000000]f[16]LBIoB
One of the Galilean satellites of Jupiter, Io is one of the most brilliant objects in space. There are eight known volcanoes on its surface that continually spew forth chemicals that color the moon in bright reds, oranges, and yellows.
Ec[000000]f[16]LBJames W. ChristyB
Twentieth-century American astronomer who discovered the moon of Pluto in 1978.
Ec[000000]f[16]LBJan OortB
Dutch astronomer of the twentieth century who discovered the billions of comets lying in deep space beyond Pluto. This "cloud" of comets is named in his honor.
Ec[000000]f[16]LBJupiterB
Jupiter is the largest planet in our solar system. It is the fifth planet from the Sun and has four satellites in orbit around it.
Ec[000000]f[16]LBlavaB
Molten rock that flows from a volcano like a river. It comes from the hot interior of the Earth and forms new land. Many islands in the Pacific Ocean, most notably Hawaii, were formed from lava flows. There are still active volcanoes on Hawaii today.
Ec[000000]f[16]LBlightningB
A flash of light in the sky, caused by static electricity leaping between two clouds or from a cloud to the Earth's surface. Lightning has been observed on other planets, too.
Ec[000000]f[16]LBmagnetic fieldB
The force field surrounding any magnet. Earth's magnetic field is built up from the hot iron core at the center of the earth.
Ec[000000]f[16]LBmassB
A body or quantity of matter.
Ec[000000]f[16]LBmeteorB
The name given to a meteoroid that enters Earth's atmosphere and burns up. It was thought that the heat was caused by friction with the atmosphere, but more recent studies indicate that it is the compression of gases in the atmosphere that causes the heat that burns up the meteoroid.
Ec[000000]f[16]LBmeteoriteB
The name of that part of a meteor that survives its blazing ride in the atmosphere and strikes Earth's surface. Large craters have been dug in the ground where a very large meteorite has struck, but usually, the meteorites are only the size of rocks.
Ec[000000]f[16]LBmeteoroidB
The name given an asteroid that leaves its orbit between Mars and Jupiter and falls toward Earth.
Ec[000000]f[16]LBmethaneB
A colorless, odorless gas that is used for fuel.
Ec[000000]f[16]LBMilky Way GalaxyB
The name of our galaxy. It was named because of its milk-like appearance in the sky. There are more than 100 billion stars in the Milky Way.
Ec[000000]f[16]LBMirandaB
The smallest of Uranus's large moons, Miranda has a very complex surface with networks of canyons within canyons. It has been described as the most bizarre body in the solar system.
Ec[000000]f[16]LBNeptuneB
Neptune is the smallest of the "gas giants" in our solar system and is in an orbit almost 2.8 billion miles from the Sun. It has a thin atmosphere consisting mostly of hydrogen, but the presence of methane gas colors it blue. Neptune has eight moons and four rings.
Ec[000000]f[16]LBNeriedB
One of the smaller satellites of Neptune. It is named for the sea nymphs of Greek mythology.
Ec[000000]f[16]LBneutron starB
A star that has collapsed after having used up its supply of fuel. Only neutrons remain in the body. If it gets dense enough, it can become a black hole. Rapidly spinning neutron stars can send out pulses of radio energy and are known as pulsars.
Ec[000000]f[16]LBNicolaus CopernicusB
Polish astronomer of the sixteenth century who discovered the true nature of the solar system. Prior to his discovery that the Earth and planets revolved around the Sun, it was believed that the Earth was the center of the universe, with the Sun and the planets and stars revolving around Earth.
Ec[000000]f[16]LBnitrogenB
A colorless, odorless gas that makes up about 80 per cent of the Earth's atmosphere.
Ec[000000]f[16]LBnuclear fissionB
Nuclear fission is the act of splitting atoms of certain elements into atoms of other elements. Fission is accompanied by a huge release of energy.
Ec[000000]f[16]LBnuclear fusionB
Nuclear fusion is a thermonuclear reaction in which nuclei of light atoms join to form nuclei of heavier atoms. The fusion in the Sun compresses hydrogen atoms so tightly that they form helium atoms, giving off the tremendous amounts of heat.
Ec[000000]f[16]LBOort CloudB
The area of space far beyond the planet Pluto that is home to billions of comets. It was named for its discoverer, Dutch astronomer Jan Oort.
Ec[000000]f[16]LBorbitB
The curved path of a planet around the Sun or a satellite around a planet.
Ec[000000]f[16]LBPercival LowellB
American astronomer of the late nineteenth and early twentieth centuries. He believed the lines on the surface of Mars were canals dug by intelligent creatures and predicted the possibility of life on Mars. (Studies from space probes have shown the canals are more like driedEc[000000]f[16]LF-up river beds from millions of years ago.) Lowell correctly predicted the position of the planet Pluto, although its existence was not proven until fourteen years after his death.
Ec[000000]f[16]LBplanetB
Any of the large bodies that revolve around the Sun in our solar system. The existence of planets around distant stars is considered possible, but has not been proven.
Ec[000000]f[16]LBPlanet "X"B
An unknown planet believed to exist beyond Pluto in our solar system. Astronomers are looking for it to explain strange motions in the orbits of Uranus and Neptune, which they believe could not be caused by Pluto alone.
Ec[000000]f[16]LBplanetary ringsB
Rings surrounding the "gas giants" in our solar system. Saturn has the most brilliant rings, but Jupiter, Uranus, and Neptune also have rings which are very thin and hardly visible from Earth.
Ec[000000]f[16]LBplanetismalsB
Small, solid objects in space believed to have existed at early stages of the development of our solar system. One theory believes that planets evolved from planetismals coming together to form larger bodies.
Ec[000000]f[16]LBplanetoidsB
Another name for an asteroid.
Ec[000000]f[16]LBPlutoB
Pluto is the ninth planet in our solar system and is 3.6 billion miles from the Sun.
Ec[000000]f[16]LBPoseidonB
Greek god of the sea; called Neptune in Roman mythology.
Ec[000000]f[16]LBPtolemaic systemB
The plan of the solar system worked out by Ptolemy in the second century A.D. in which he proposed that the Sun and other planets revolved around Earth. This system was the accepted explanation of the solar system for more than one thousand years.
Ec[000000]f[16]LBPtolemyB
An Alexandrian astronomer in the second century A.D. who described the solar system as a system of spheres, one inside the other, with the Earth at the center and the planets and Sun revolving around it.
Ec[000000]f[16]LBpulsarB
A neutron star that sends out regular pulses of radio waves at regular intervals.
Ec[000000]f[16]LBradio telescopeB
A very sensitive radio receiver that can detect radio waves from outer space. Much information about distant stars and galaxies can be obtained by using radio telescopes.
Ec[000000]f[16]LBreflecting telescopeB
An astronomical telescope that uses a concave mirror to collect light from the universe and focus it so it can be studied by astronomers.
Ec[000000]f[16]LBrefracting telescopeB
An astronomical telescope that uses a tube and a series of lenses to produce an inverted image.
Ec[000000]f[16]LBRiver StyxB
The river surrounding the underworld of Pluto in Greek mythology. Charon was the boatman who ferried the souls of the dead across the river to the underworld.
Ec[000000]f[16]LBsatelliteB
A natural or man-made body that revolves around a planet. Our Moon is a satellite, as are the space probes and communication satellites launched by rockets from Earth.
Ec[000000]f[16]LBSaturnB
Saturn is the second largest planet in the solar system and orbits the Sun at a distance of 887 million miles. Saturn is unique for its ring system, which circles the planet about 4,350 miles above the surface but stretches out almost 46,000 miles. The rings are made up of billions of Ec[000000]f[16]LFice particles. Saturn also has 23 known moons and probably several more that have yet to be discovered.
Ec[000000]f[16]LBSaturn's ringsB
The bright rings of matter that surround the planet Saturn. They can easily be seen with a telescope.
Ec[000000]f[16]LBshepherd satelliteB
A small moon that revolves within the orbit of rings around planets and keeps the matter in the rings from spreading outward into space.
Ec[000000]f[16]LBsolar windB
Solar wind is created by activity on the Sun's surface. The activities, such as sunspots, solar flares, and prominences, sends tiny charged particles outward in all directions at speeds of about three hundred miles per second. This stream of particles is known as the solar wind.
Ec[000000]f[16]LBspace probeB
A spacecraft designed to explore other planets and send back photographs and other data.
Ec[000000]f[16]LBstarB
An object in space made up of mostly hydrogen. The gas is compacted so tightly in the center that nuclear fusion takes place, breaking the hydrogen down into helium and other elements and creating temperatures in the millions of degrees. The heat is so great that the ball of gas Ec[000000]f[16]LFglows brightly. Our Sun is the nearest star to Earth.
Ec[000000]f[16]LBsupernovaB
An exploding star in the universe that sends out as much as a hundred million times more light and energy than the Sun.
Ec[000000]f[16]LBtelescopeB
An optical device invented in the sixteenth century by Galileo, which allows us to study distant objects. He discovered the four moons of the planet Jupiter in 1610 by using his telescope.
Ec[000000]f[16]LBTethysB
One of the largest moons of Saturn whose surface is heavily cratered with a canyon that stretches over three-fourths of the satellite's surface. It is named for the sea goddess in Greek mythology.
Ec[000000]f[16]LBTitanB
Largest satellite of Saturn and second largest in the solar system. Titan is larger than the planet Mercury and is unusual in that it has an atmosphere composed mostly of nitrogen. It was named for a group of early Roman gods and goddesses.
Ec[000000]f[16]LBTitaniaB
Largest moon of Uranus, Titania seems to have a complex surface marked by valleys and fault lines, indicating evidence of earlier global tectonics.
Ec[000000]f[16]LBtornadoB
A violent storm on Earth, marked by a funnel cloud with winds of up to 300 miles (480 kilometers) per hour inside the funnel. It is caused by rapid mixture of warm and cold air that creates the turbulence that brings the funnel cloud.
Ec[000000]f[16]LBTritonB
Triton is the largest of Neptune's satellites. It was named for the son of Neptune and Amphitrite in Roman mythology and is pictured as a fish with a human head.
Ec[000000]f[16]LBUraniaB
The muse of astronomy in mythology.
Ec[000000]f[16]LBUranusB
Uranus is the first planet discovered in modern times, by William Herschel in 1781. It is the seventh planet from the Sun and twice as far out as its neighbor Saturn. It is 1.8 billion miles from the Sun and has rings as well as 15 known moons.
Ec[000000]f[16]LBvolcanoB
An opening in the Earth's surface through which molten rock, known as lava, erupts from time to time. These openings are usually at the tops of mountains, but some are in the floors of the oceans.
Ec[000000]f[16]LBVoyager space missionsB
Space probes launched by the United States that passed Jupiter in 1979, Saturn in 1980, Uranus in 1986, and Neptune in 1989. Thousands of photos were sent back to Earth from IVoyager 1I and IVoyager 2I, giving scientists most of the knowledge they now have of the outer Ec[000000]f[16]LFplanets. The Voyager missions made many startling discoveries, such as finding four rings around Neptune. The last photo from IVoyager 2I was taken in February 1990 from 3.7 billion miles (5.9 billion kilometers) away from the Sun and showed the Sun and most of the solar system. Only Mercury, Mars, and Pluto are not seen in this famous photograph.
Ec[000000]f[16]LBWilliam HerschelB
Herschel was a German astronomer who worked and studied in England. In 1781 he discovered the planet Uranus by using a reflecting telescope that he had built.
Ec[000000]f[16]LBWilliam ShakespeareB
The greatest dramatist and poet of the English language, Shakespeare was born in 1564 and died in 1616. He wrote thirty-seven plays and more than one hundred sonnets. The moons of Uranus are all named after characters in Shakespeare's plays.
