28 July 1919 The International Astronomical Union (IAU) is formed. This is an international association of professional astronomers active in professional research and education in astronomy. It acts as the internationally recognized authority for assigning designations to celestial bodies. At the 2006 IAU General Assembly held in Prague it demoted Pluto to dwarf planet status, thereby leaving us with eight planets in the solar system.
20 July 1969 Apollo 11 lands on the Moon. Neil Armstrong becomes the first human to walk on the
USA time Moon uttering the famous words “that’s one small step for (a) man, one giant leap for mankind”. About 20 minutes later he was joined by Buzz Aldrin. Michael Collins remained in the Command Module orbiting the Moon.
16 July 1994 Comet Shoemaker-Levy crashes into Jupiter providing the first direct observation of an extraterrestrial collision of Solar System objects. The first impact occurred on 16 July 1994, when fragment A entered Jupiter's southern hemisphere at a speed of about 60 km/s. Over the next six days, 21 distinct impacts were observed, with the largest coming on 18 July when fragment G struck Jupiter. This impact created a giant dark spot over 12,000 km across. You can see Jupiter in the sky in July 2018.
04 July 1868 Henrietta Swan Leavitt. American astronomer. She discovered the relation between the luminosity and the period of Cepheid variable stars. It was this discovery that allowed astronomers to measure the distance between the Earth and faraway galaxies.nCepheid variables are still used today to help us understand the distance to astronomical objects.
23 July 1928 Vera Rubin. American astronomer. She pioneered work on galaxy rotation rates, which became known as the galaxy rotation problem, and was evidence of the existence of dark
matter. Although initially met with skepticism, her results were confirmed over
15 July 1943 Jocelyn Bell Burnell. Northern Ireland Astrophysicist. As a postgraduate student at Cambridge University she discovered the first radio pulsars in 1967. Not being able to recognize the signals and thinking it may have been artificially created she labelled them LGM1 for “little green men 1” ! She was President of the Royal Astronomical Society from 2002 to 2004. In 2014, she became the first woman to become President of the Royal Society of Edinburgh.