Astronomers

Aristarchus

310 BCE

Aristarchus was born in 310 B.C. on the Aegean island of Samos. Not much is known about his life, except that he was a friend of Archimedes. Archi. was responsible for making Aris's ideas known. He told the King of Syracuse that Aris. believed that the Earth orbited the Sun -not the other way around- and also that the Earth was spinning, accounting for the rising and setting of the Sun. "In the eyes of his fellow philosophers, Aristarchus was at best a radical thinker, at worst a heretic."

Aristarchus

310

The invention of the heliocentric model is traditionally given to Copernicus, but it was actually Aristarchus who invented it. "Aristarchus was the first mathematician to apply geometry to cosmic measurement: he estimated the Moon’s distance by noting the width of Earth’s shadow during a lunar eclipse, and the Sun’s distance from the angle formed by the Earth, Moon, and Sun when a half-Moon appears in the sky." He was also a friend of Archimedes and beat Copernicus by 1,880 years.

Ole Rømer

1644

In 1638, while under house arrest, Galileo tried to measure the speed of light. He incorrectly deemed it to be infinite, or too fast to be measured in "any earthbound experiment." 30 years later, a scientist named Ole Rømer measured that light travels through space at about 140,000 miles per second by measuring Io, one of Jupiter's moons. He was incorrect -the speed of light is actually 186,000 mps- but his discoveries helped scientists like Issac Newton that the speed of light is not infinite.

James Bradley

1721

Nicolaus Copernicus published his heliocentric model of the universe in 1530, but it lacked observable proof for a long time... (That's probably why the church wanted to kill him.) Until 1721 when James Bradley discovered the Gamma Draconis did indeed have a wobble, like the heliocentric model said it did. He also discovered the Earth's axis has a nutation, whatever that is. Bottom line, because of the discovery of the wobble and nutation "we owe the exactness of modern astronomy" to J. Bradley.

John Herschel

1825

John Herschel invented the actinometer and named seven moons of Saturn and four moons of Uranus.

Friedrich Wilhelm Bessel

1841

In 1837, Friedrich Wilhelm Bessel tried to do what many great astronomers -even Copernicus- had tried and failed to do: measure the distance to a star. He accomplished this by gauging the star's parallax, or tiny annual wobble. He measured the star's parallax to be 61 Cygni, or nine hundred-thousands of a degree. That made the star to be 600,000 times the Sun's distance. He also generalized a special type of mathematical functions which were named after him: Bessel functions.

Asaph Hall

1877

In August 1877, Asaph Hall began a search for Mar's moons. He discovered the moons Deimos on August 12, and Phobos on August 16. Two moons, two discoveries. ;) Two craters on Phobos are named Hall and Stickney, in honor of Asaph Hall and his wife, Angeline Stickney Hall.

George Ellery Hale

1890

George Ellery Hale discovered magnetic fields in sunspots and invented the solar camera.

Henrietta Swan Leavitt

1912

In the late 1800's and early 1900's measuring a object's distance from Earth was pretty hard. I'm not sure it's even that easy today. An astronomer named Henrietta Swan Leavitt figured out how to do that. And I'm paraphrasing in the next bio card:

Henrietta Swan Leavitt

1912

"she discovered that the period of a Cepheid’s brightening-dimming cycle closely correlates with its average brightness. Leavitt proposed to astronomers that, once calibrated against the properties of well-studied Cepheids, the period-luminosity law, as it is now known, would provide the means to infer any Cepheid’s distance — and, by extension, that of its host star cluster or galaxy. She published her findings in a Harvard College observatory circular in 1912."

Annie Jump Cannon

1925

Annie Jump Cannon -along with Edward C. Pickering- invented the Harvard Classification Scheme. That's pretty much it. Oh! She could classify 300 stars an hour and was friends with Henrietta Swan Leavitt. Now that's pretty much it.

Milton Humason

1928

Milton Humason discovered Comet C/1961 R1 (Humason) and helped Edwin Hubble create Hubble's law.