Famous Scientists
Nicolaus Copernicus (1473 - 1543)
Birthplace: Thorn, PolandCopernicus proved that the classical Greek theory of Astronomy was dead wrong. Up until Copernicus's time, almost everyone--including Astronomers, thought that the planets and other celestial bodies in our solar system orbited our planet, Earth.
Copernicus argued for a "heliocentric" model of our solar system, where the Sun was at the center of our galaxy. He was right--the Earth and all of the other planets in the Milky Way orbit around the Sun.
Today, we use Earth's orbital cycle to measure time. One year is 365 days long, because that's how long it takes the Earth to make a full circle or orbit around the Sun. Copernicus's discovery changed how we think about outer space. Thanks to Copernicus, we now know that the universe does not revolve around us. Because of this, Copernicus is often called the "Father of Modern Astronomy."
Galileo Galilei (1564 - 1642)
Birthplace: Pisa, ItalyGalileo has also been given the nickname, "the Father of Modern Science."Galileo ranks with Archimedes, Newton, and Einstein as one of the greatest scientists of all time. His discoveries, made with the crudest of equipment, were brilliant examples of scientific reasoning. He improved the telescope so that he could see planets and stars better at night. Then he made scientific observations that supported Copernicus's theory that the Earth orbited the Sun. Using the telescope to observe the night sky, Galileo also confirmed the phases of Venus, proved that the planet Jupiter had at least four moons that orbited around it, and showed that there were different color spots on the Sun, called sunspots.
Sir Isaac Newton (1643-1727)
Birthplace: Lincolnshire, EnglandSir Isaac Newton created and proved three scientific laws of motion that told us more about how and why things move, speed up, and stop. He also created the law of Universal Gravitation which was based on the theory that every particle (even tiny bits of dust) in the universe excerpted some level of gravitational force. We now know that gravity is the reason why we can stand and walk around. It's why when you drop something, it falls to the ground rather than floating off into space. Newton showed the world that gravity caused apples to fall out of trees and the moon to orbit, or move in circles, around our planet Earth. Years later, another famous scientist named Albert Einstein improved Newton's law of Universal Gravitation by using his own observations and discoveries to create the Theory of Relativity.
Stephen Hawking (1942-present)
Birthplace: Oxford, EnglandAfter Albert Einstein, Stephen Hawking is probably the most famous Astrophysicist of all time. He's known for his study of certain physical characteristics of black holes, work that led to greater understanding of the origin of the universe. Hawking's A Brief History of Time: From the Big Bang to Black Holes (1988) was a national best seller. It provides an overview of the origin and structure of the universe.
Stephen Hawking is paralyzed so he uses a special computer to communicate. Here's a video of Stephen Hawking giving a speech about the Big Bang, the gigantic explosion he believes created our universe. In this speech, Hawking discusses how life came to be and whether there could be life on other planets in our universe.
Edmund Halley (1656-1742)
Birthplace: London, EnglandEdmund Halley is best known for his studies of the comet that bears his name, Halley's Comet. He observed this famous comet in 1682, calculated its orbit, and predicted its reappearance (when it would come back and fly by Earth again). As he had foretold, Halley's comet reappeared in 1758. This was the first time that the reappearance of a comet had been correctly predicted. Halley's comet is visible from Earth once every 75-76 years. It was last seen in 1986 and the next time that it is predicted to reappear is forty-seven years from now, in 2061. You will be 55 years old next time Helley's comet is visible from Earth. Halley was friends with Sir Isaac Newton, and it was Halley that paid for and convinced Newton to publish the Principia, the document that included the Laws of Gravitation.
Halley was also an inventor. He built a successful diving bell and found a way to supply divers with compressed air so that divers could breath underwater.
Edwin Hubble (1889-1953)
Birthplace: Marshfield, Missouri
Hubble revolutionized astronomy by showing that the universe is much larger than scientists had previously believed.
Through scientific observations of outer space, Hubble was able to prove that a force (called recessional velocity) causes the universe to keep expanding (getting bigger and more spread out). Astronomers call this discovery of our universe's ever-growing magnitude (size) Hubble's Law.
Because Hubble's discovery was so big and important, lots of things have been named after him including NASA's famous Hubble Telescope--which orbits the Earth and takes pictures, the Edwin P. Hubble Memorial Highway in Missouri, and the Hubble Crater on the surface of the moon.
Carl Sagan (1934-1996)
Birthplace: Brooklyn, New York
Sagan was a famous scientist who made science, especially Astronomy, into something that everyone could learn about and study at home--or at school by reading books or articles in magazines and watching popular TV shows. Before Sagan, people didn't pay very much attention to our galaxy or know much about it unless they were scientists.
Sagan appeared frequently on television to talk about things in the universe and he wrote numerous best-selling books that people could read and understand, even if they weren't Astronomers or Astrophysicists. Sagan was best known for his 1980 television series, Cosmos: A Personal Voyage, and a book he wrote which was also titled Cosmos. In 1980, before your teachers were born, Cosmos: A Personal Voyage was the most watched show on public television (PBS). Since then, Cosmos: A Personal Voyage has been broadcasted (shown) in over 60 countries and seen by over 500 million people. Through TV and books, Sagan has taught people all over the world about outer space.
Sagan also won a Pulitzer Prize, a famous international award, for a book he wrote in 1977 that talked about human evolution and included his theories on how humans gradually became smarter and smarter over periods of thousands of years.