Clyde William Tombaugh was an American astronomer. Although he is best known for discovering the dwarf planet Pluto in 1930, the first object to be discovered in what would later be identified as the Kuiper belt, Tombaugh also discovered ma...

Kuiper is considered to be the father of modern planetary science for his wide ranging studies of the solar system. Although he contributed to astrophysics, established the atmosphere of Saturn's moon Titan, and discovered Saturn's moon Mir...

Jan Hendrik Oort was a Dutch astronomer who made significant contributions to the understanding of the Milky Way and who was a pioneer in the field of radio astronomy. His New York Times obituary called him “one of the century's foremost ex...

Fritz Zwicky was a Swiss astronomer. He worked most of his life at the California Institute of Technology in the United States of America, where he made many important contributions in theoretical and observational astronomy. In 1933, Zwick...

Georges Lemaître was a Belgian Roman Catholic priest, honorary prelate, professor of physics and astronomer at the Catholic University of Leuven. He sometimes used the title Abbé or Monseigneur. Lemaître proposed what became known as the Bi...

Edwin Powell Hubble was an American astronomer who played a crucial role in establishing the field of extragalactic astronomy and is generally regarded as one of the most important observational cosmologists of the 20th century. Hubble is k...

Alexander Alexandrovich Friedman or Friedmann was a Russian and Soviet cosmologist and mathematician. He discovered the expanding-universe solution to the general relativity field equations in 1922, which was corroborated by Edwin Hubble's...

Albert Einstein was a German-born theoretical physicist. Einstein developed the theory of relativity, one of the two pillars of modern physics (alongside quantum mechanics). Einstein's work is also known for its influence on the philosophy...

Heinrich Louis d'Arrest was a German astronomer, born in Berlin. While still a student at the University of Berlin, d'Arrest was party to Johann Gottfried Galle's search for Neptune. On September 23, 1846, he suggested that a recently drawn...

John Adams was an English mathematician and astronomer who predicted the existence of Neptune. While a student at Cambridge he wrote this note (found only after his death) dated Jul. 3, 1841: Formed a design at the beginning of this week of...

Johann Gottfried Galle was a German astronomer at the Berlin Observatory who, with the assistance of student Heinrich Louis d'Arrest, was the first person to view the planet Neptune, and know what he was looking at, on 23 September, 1846. H...

Urbain Jean Joseph Le Verrier was a French mathematician who, beginning in 1838, studied the causes of perturbations in the Solar System. His work led to improved knowledge of the masses of the planets, the scale of the Solar System, and th...

The Reverend Dr Robert Stirling was a Scottish clergyman, and inventor of the stirling engine. He invented what he called the Heat Economiser (now generally known as the regenerator), a device for improving the thermal/fuel efficiency of a...

Joseph Ritter von Fraunhofer is known for discovering the dark absorption lines known as Fraunhofer lines in the Sun's spectrum, and for making excellent optical glass and achromatic telescope objectives. In 1814 Fraunhofer invented the...

Johann Carl Friedrich Gauss was a German mathematician, who contributed significantly to many fields, including number theory, algebra, statistics, analysis, differential geometry, geodesy, geophysics, electrostatics, astronomy, Matrix theo...