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In this month: August

28 August 1789

Saturn’s moon Enceladus is discovered by William Herschel using his new 1.2 m telescope which was then the largest in the world. Enceladus is one of the major inner satellites of Saturn and orbits the planet every 32 hours 53 minutes hours, fast enough for its motion to be observed over a single night of observation. Caroline Herschel worked closely with her brother.

12 August 1877

Mars moon Deimos (image above by NASA/JPL-Caltech/University of Arizona) is discovered by Asaph Hall at the United States Naval Observatory. The moon is named after the son of Ares, the Greek God of War, and means terror.

It is little more than a chunk of rock at 11km in length and orbits Mars every 30.3 hours at a distance of 23,460 km. However, its orbit is slowly taking it away from the planet and it will eventually be cast off into space when it gets too far from the gravity of Mars to remain in orbit.

25 August 2012

Voyager 1 enters interstellar space becoming the first spacecraft to leave the solar system. The

spacecraft is still receiving commands but due to the distance the signal strength is very weak, only one-

tenth of a billion-trillionth of a watt. The signal, traveling at the speed of light, takes 17 hours to

reach Earth. On board is a record featuring one and a half hours of world music and greetings to the universe in 55

different languages.


Astronomical instruments used by Flamsteed at Greenwich, as depicted in: John Flamsteed. Historiae coelestis Britannicae. Londini: typis H. Meere, 1725 [Rare Books Collection FOL. QB7 FLA]

19 August 1646

John Flamsteed. English astronomer. The first Astronomer Royal and the first Director of Greenwich

Observatory. He was a highly skilled mathematician and observer, and he oversaw the construction of greenwich Observatory and was involved in the design of some of the most important instruments used there, such as the mural arc used to measure the position of stars pictured above, when it opened. Another of Flamsteed's achievements was compiling a 3,000 star catalogue which accurately doubled the known location of stars in the western world.

01 August 1818

Maria Mitchell. American astronomer. The first American female to work as a professional astronomer.

She was Professor of Astronomy at Vassar College and Director of Vassar College Observatory.

In 1847 she discovered a comet which was named after her “Miss Mitchell’s Comet”.

05 August 1930

Neil Armstrong. American astronaut. First human to walk on the Moon during the Apollo 11 mission.

Prior to this he flew on Gemini 8. After the space shuttle Challenger accident in 1986 he served on the

investigation panel as the Vice Chairman of the Presidential Commission.

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