Science Dictionary

He is famous for a phrase he never said, for wearing turtlenecks and for hosting the original 'Cosmos' TV series. As enthusiastic about the stars as he was about marijuana, Carl Sagan led a very surprising life.

By Laurie L. Dove

He starred with Superman, drove the getaway car at Pluto's demise and was voted sexiest astrophysicist by People magazine. Is there anything Neil deGrasse Tyson can't do?

By Laurie L. Dove

Is this famous primatologist atheist, agnostic or theistic? Find out as we bravely explore whether science and religion must always collide.

By Marianne Spoon

He may have been born in Brooklyn, but Carl Sagan was gunning for the stars as soon as he arrived in this world. Get to know the scientist whose infectious delight in the universe still holds us spellbound.

By Marianne Spoon

He ventured to the abyss of black holes, wagered on the information paradox and floated around in zero gravity. Meet the man, the legend, the super scientist: Stephen Hawking.

By Marianne Spoon

How cool would that be to stand amongst the company of fellow laureates like Mother Teresa or Albert Einstein? We have some ideas for scoring you one.

By Marianne Spoon

Frequency has to do with wave speed and wavelength is a measurement of a wave's span. Learn how frequency and wavelength of light are related in this article.

By HowStuffWorks.com Contributors

He was born exactly 300 years after Galileo died. He never won a Nobel Prize, although he was awarded a guest spot on “The Simpsons.” What else do you know (or not know) about this acclaimed physicist?

By Jane McGrath

You've heard of the big bang, of course, but do you have any idea as to what was happening during that massive flurry of activity billions of years ago?

By Robert Lamb

Every day, astronomers unravel a little more of the universe's inner workings, but the jury is still out on 95 percent of its contents.

By Robert Lamb

Hewish, Antony (1924-) is a British astronomer and astrophysicist, a scientist who studies the physical nature, origin, and development of the solar system, galaxies, and the universe.

Payne-Gaposchkin, Cecilia Helena (1900-1979) was a British-born astronomer who became an authority on variable stars (stars that change in brightness) and the structure of the Milky Way Galaxy.

Eudoxus of Cnidus (NY duhs or kuh NY duhs) (400 B.C.?-350 B.C.?) was a Greek astronomer who made important contributions to the field of geometry.

Al-Tusi, Nasir al-Din (1201-1274) was one of the greatest scholars of his time and one of the most influential figures in Islamic intellectual history.

Aberration of Light is a phenomenon in which a star or other celestial body, as viewed from the earth, appears to be slightly displaced from its true position.

Andromeda Galaxy, a spiral galaxy that is larger than the Milky Way (the galaxy to which Earth belongs) but similar to it in structure, and the closest to ours.

Transit, in astronomy, is the passage of one celestial body across the disc (face) of a larger, more distant body, or across the observer's meridian.

Azimuth, the horizontal direction of an object, measured clockwise in degrees, minutes, and seconds of arc from true north or south along the theoretical horizon.

Bolometer, an instrument used to measure infrared, or heat, radiation. The bolometer is essentially a very sensitive thermometer.

Chronometer, a timepiece that is exceptionally accurate. Traditionally, the term refers to the marine chronometer, a rugged mechanical instrument used at sea to keep time for navigational purposes.

Cosmogony, the study of the origin and development of the universe as a whole and of the individual bodies that compose it.

Day, in astronomy, the average length of time between successive noons. Noon is defined as the instant when the sun is highest in the sky.

Double Star, a pair of closely-spaced stars that to the unaided eye usually appear as a single star.

Hourglass, a device for measuring time. In its usual form it consists of two cone-shaped or oval glass receptacles joined by a narrow neck.

Magnitude, in astronomy, a unit of measurement of the brightness of stars. The scale of magnitude extends from negative numbers (for example, the minus first magnitude) for very bright stars to positive numbers (for example, the fourth magnitude) for dimmer ones.