Here’s our alphabetical list of the most popular astronomers, or contributors to astronomy, astrophysics, or cosmology on the Famous Scientists website, ordered by surname.

The iridium layer, dinosaur death by meteorite impact, and subatomic particle discoveries.

An ancient scientific revolution: the first person in history to recognize that our planet is free in space and does not need to sit on something.

Promoted the idea that the earth follows a circular orbit around the sun eighteen centuries before Nicolaus Copernicus resurrected the idea.

Produced the best star catalog that had ever been compiled and measured the orbit of Mars with unprecedented accuracy, paving the way for Kepler’s laws of planetary motion and Newton’s law of gravity.

Discovered that massive stars can collapse under their own gravity to reach infinite densities. Today we call these collapsed stars black holes.

Started the scientific revolution with his book

*The Revolutions of the Celestial Spheres*, explaining his belief that the solar system is centered on the sun, not the earth.

Devised an atomic theory featuring tiny particles always in motion interacting through collisions; advocated a universe containing an infinity of diverse inhabited worlds governed by natural, mechanistic laws rather than gods; deduced that the light of stars explains the Milky Way’s appearance; discovered that a cone’s volume is one-third that of the cylinder with the same base and height.

A founder of the search for extraterrestrial intelligence; devised the Drake equation to estimate the number of intelligent civilizations in our galaxy; first person to map the center of the Milky Way galaxy.

Founded mathematical astronomy by creating the first mathematical model of the universe, turning physical reality into something more abstract offering a new vantage point from which we could study the universe.

The father of modern science, Galileo discovered the first moons ever known to orbit another planet and that the Milky Way is made of stars. He rationalized how objects are affected by gravity, stated the principle of inertia, and proposed the first theory of relativity.

The last master of all mathematics, Gauss revolutionized number theory; he invented the method of least squares and the fast Fourier transform to recover the position of the lost dwarf planet Ceres.

The first person in history to map a heavenly body after observing it with a telescope – the moon. Probably first to observe sunspots with a telescope, allowing him to determine the sun’s rotation rate.

Discovered five comets; produced an award-winning catalogue of nebulae; the brother-sister team of William & Caroline Herschel increased the number of known nebulae from about 100 to 2,500.

Produced the first global survey of the night skies, discovered hundreds of nebulae and thousands of double stars; took the first ever photograph on glass plate; invented the actinometer to measure the heating power of radiation.

One of antiquity’s greatest scientists: founded the mathematical discipline of trigonometry; measured the earth-moon distance accurately; discovered the precession of the equinoxes; and documented the positions and magnitudes of over 850 stars. His combinatorics work was unequalled until 1870.

Proved that most of the naturally occurring elements in the periodic table were made inside stars and distributed through space by supernova explosions; coined the phrase ‘Big Bang’ while strenuously denying that there had ever been one; argued for an expanding Steady State universe with no beginning or end.

Discovered there are galaxies beyond our own. Showed we live in a universe of many galaxies, each an isolated ‘island universe,’ separated by immense distances. Independently discovered and popularized Hubble’s law, believed by most cosmologists to indicate we live in an expanding universe.

A poet, philosopher and scientist, Khayyam calculated the length of a year to the most accurate value ever, and showed how the intersections of conic sections can be utilized to yield geometric solutions of cubic equations.

Discovered the solar system’s planets follow elliptical paths; identified that the tides are caused mainly by the moon; proved how logarithms work; discovered the inverse square law of light intensity; his laws of planetary motion led Newton to his law of gravitation.

Discovered that Cepheid variable stars act as a ‘standard candle,’ opening the door to measuring the distances to far-distant stars and the discovery of galaxies beyond the Milky Way.

‘Discovered’ an enormous network of canals and oases on Mars, from which he deduced the existence of an advanced Martian civilization; his search for Planet X led to the discovery of Pluto.

Discovered that space and the universe are expanding; discovered Hubble’s law; proposed the universe began with the explosion of a ‘primeval atom’ whose matter spread and evolved to form the galaxies and stars we observe today.

The first person in history to suggest black holes could exist; invented the torsion balance to weigh our planet; used probability theory to establish that some star groupings are non-random and therefore perhaps held together by gravity.

Profoundly changed our understanding of nature with his law of universal gravitation and his laws of motion; invented calculus, the field of mathematics that dominates the physical sciences; generalized the binomial theorem; built the first ever reflecting telescope; showed sunlight is made of all the colors of the rainbow.

Discovered that the most abundant chemical elements in stars and hence in the universe are hydrogen and helium.

Author of the Almagest, which contained a catalogue of over a thousand stars with positions, relative brightnesses, and constellations; and a mathematical model predicting the movements of the planets that was unsurpassed for almost 1,500 years.

The first astrogeologist and a founder of planetary impact science; proved large craters on Earth were caused by collisions with asteroids and comets rather than volcanic activity; proposed microscopic life could travel between planets on rocks blasted into space by asteroid impacts.

Discovered deuterium; showed how isotope ratios in rocks reveal past Earth climates; founded modern planetary science; the Miller-Urey experiment demonstrated that electrically sparking simple gases produces amino acids – the building blocks of life.