Science Dictionary

Do you know what a meteor is, or what scientists mean when they are talking about cryogenics? Our collection of science terms explains the meaning of some of the most common scientific ideas.

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Physicist and cosmologist Stephen Hawking was a fierce spirit who symbolized the foibles and complexities inherent in human nature. Learn more about him by taking our quiz.

By Nathan Chandler

The world often seems chaotic and events appear to occur randomly, but what's the difference between chaos and randomness?

By Mitchell Newberry

So much about galaxies remains a mystery. We know what they're made of and that we live in one (the Milky Way), but how many galaxies are in the universe?

By Craig Freudenrich, Ph.D.

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While routinely scanning the stars, NASA scientists came across something they didn't expect to see: a vast area of space empty of stars, planets and matter.

By Jacob Silverman

Space collisions are the universe's car wrecks. Only in outer space, it's stars, asteroids and even galaxies doing the smashing.

By John Fuller

We take much for granted about our universe, like it's getting bigger. What if the universe stopped expanding and started collapsing inward with a giant crunch?

By William Harris

The man immortalized on the left was behind the three laws of motion and the universal law of gravitation. He was also competitive, temperamental and fascinated with alchemy. How well do you know Newton?

By Jacob Silverman

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Margulis, Lynn Alexander (1938-), an American biologist, helped advance the study of the origins of cells.

Berg, Paul (1926-), an American biochemist and molecular biologist, has been at the forefront of genetic engineering, both as an inventor of a pioneering procedure and as an advocate concerned about the risks of genetic research.

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.

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.

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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.

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.

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.

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Midnight Sun, a name given the sun when it can be seen at midnight during the Arctic or Antarctic summer.

The nebular theory, also known as nebular hypothesis, presents one explanation of how the solar system was formed, proposed by Pierre Simon de Laplace in 1796.

By Yara Simón

Planetarium, is an educational device for showing the locations and movements of the planets and other objects in the universe.

Planetesimal hypothesis is a theory of the origin of the solar system. It was proposed by Forrest R.

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Solar wind is a continuous stream of mostly hydrogen and helium that flows outward from the sun in all directions. It does everything from disrupt GPS signals to create the aurora borealis.

By Mark Mancini

Van Allen Radiation Belts, two zones encircling the earth in which there are relatively large numbers of high-energy (fast-moving) charged particles.

By Yara Simón

Nebulae are collections of dust and gases scattered across the galaxy. They're the sites where stars are born and what's left behind after they die.

By William Harris

The big bang theory is well-known, but there are many misconceptions about it. Like what? Let's start with this one: There was no bang.

By Jonathan Strickland

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From astronauts to doctors to an archaeologist, we present eight scientists whose contributions to science, engineering and math were inseparable from their identities as Indigenous Americans.

By Dave Roos

Questions, theories and debates about quantum physics can get muddled because of a number of myths and misconceptions. Here are four of them.

By Alessandro Fedrizzi & Mehul Malik