Astro Anniversaries

December

Day	Year	Event
2	1973	Pioneer 10 became the first spacecraft to send back images of an outer planet (Jupiter) that showed more detail than anything we could obtain from Earth; later, Pioneer 10 became the first spacecraft to go beyond the realm of the known planets into deep space.
4	1639	Jeremiah Horrocks in England became the first modern observer to see a transit of Venus (when Venus crosses the face of the Sun as seen from Earth,) allowing him to make a rough estimate of the scale of the solar system. (Horrocks himself would have said he made the observation on Nov. 24, since England had not yet switched to the Gregorian calendar.)
6	1891	Will Hay born. Well-known as a comedian, Will Hay was also a keen amateur astronomer. He was a member of the BAA and is noted for having discovered a Great White Spot on the planet Saturn in 1933.
7	903	Abd al-Rahman al-Sufi born. He was a Persian astronomer who constructed a great catalogue of the “fixed stars” (the most important star catalogue since Ptolemy), measured the precise length of the year and the inclination of the ecliptic, and made the first recorded observation of what today is called the Andromeda Galaxy.
7	1905	Gerard Kuiper born. He was a Dutch-American astronomer and was the key figure in the renaissance of 20th century planetary astronomy. His work on comet orbits suggested the existence of what is now called the Kuiper Belt.
7	1968	NASA launched Orbiting Astronomical Observatory 2, the first successful telescope platform orbiting in space. There was a set of instruments on board for observing the universe in ultraviolet.
7	1995	The Galileo probe became the first spacecraft to go into orbit around a giant planet (Jupiter). Put another way, it became the first artificial moon of a giant planet.
11	1863	Annie Cannon born. She fleshed out our modern classification system for stars and classified the spectra of a huge number of stars.
13	1920	At the Mt. Wilson Observatory, Albert Michelson, Francis Pease, and John Anderson used an interferometer to measure the diameter of another star (Betelgeuse) directly.
14	1546	Tycho Brahe born. His careful measurements of the motion of the planets informed Johannes Kepler’s laws of planetary motion.
14	1807	Thomas Webb born. Webb was a clergyman and amateur astronomer, and is well-known for his classic astronomical observing guide, Celestial Objects for Common Telescopes, which was first published in 1859.
14	1962	NASA’s Mariner 2 became the first spacecraft to have a close encounter with another planet (Venus), passing within 22,000 miles of the planet and measuring the high temperature of its atmosphere.
15	1970	The Russian Venera 7 probe became the first human craft to land on another planet (Venus) and transmit information back to Earth.
16	1857	Edward E. Barnard born. He discovered Barnard’s Star, the star with the greatest proper motion, and became a pioneer in the photographic study of nebulae and our galaxy.
19	1852	Albert Michelson born. He measured the speed of light and developed the astronomical interferometer, making the first direct measurement of the diameter of a star. He won the Nobel Prize for Physics in 1907.
22	1911	Grote Reber born. For about a decade, he was the only working radio astronomer in the world.
25	1642	Isaac Newton born. He would grow up to establish “the system of the world” – the laws of motion and gravity.
25	1904	Gerhard Herzberg born. A pioneer spectroscopist who helped us understand and observe the spectra of molecules on Earth and in space. He won the 1971 Nobel prize in Chemistry.
27	1571	Johannes Kepler born. He used Tycho Brahe’s observations to develop the laws of planetary motion.
28	1882	Arthur Eddington born. He was a key figure in our theoretical understanding of how stars form and how they make their energy; he lead the 1919 eclipse expedition that confirmed a key prediction of Einstein’s General Theory of Relativity.
28	1944	Sandra Faber born. She made pioneering contributions to our understanding of the evolution of galaxies, helped diagnose and fix the Hubble Space Telescope, and helped define the scientific objectives and design of the instruments for the Keck Telescopes.
31	1864	Robert Aitken born. He was perhaps the greatest discoverer and cataloguer of binary stars in history.

LAST UPDATED: 2023-11-30