In this month: April 2022

24th April 1957

The first edition of The Sky at Night a monthly documentary television programme on astronomy is shown on British television by the BBC. It featured Sir Patrick Moore, (pictured left in a screenshot taken during the first few episodes) who presented the programme until his death in December 2012.

The monthly programme began at the start of an exciting period of space exploration, less than six months before the launch of the Sputnik satellite. Over its life The Sky at Night has followed all major events and discoveries in astronomy with Sir Patrick Moore's knowledge and enthusiasm for his subject being the biggest factor for its enduring success.

Over his 55 year period in hosting the show Moore missed only one show in July 2004 due to a bout of food poisoning. The show is still aired today with Lucie Green, Chris Lintott and Maggie Aderin-Pocock presenting the show after Moore’s death. In 2007 the International Astronomical Union named an asteroid 57424 Caelumnoctu, the number referring to the first broadcast date and the name being Latin for "The Sky at Night", and the Royal Mail issued a set of six astronomy stamps to celebrate the 50th anniversary of the programme.

7th April 1983

The first spacewalk in the Space Shuttle program is performed by astronauts Donald Petersen and Story Musgrave during mission STS-6 which is also the maiden flight of the Space Shuttle Challenger. Lasting 4 hours and 10 minutes the spacewalk’s main aim was to test spacewalk operations, space suits and procedures astronauts would use in the Shuttle’s payload bay should an emergency spacewalk become necessary. The spacewalks during the Space Shuttle era demonstrated that astronauts could capture, repair and redeploy satellites, test future refuelling of spacecraft and evaluate assembly techniques. They were also indispensable for the assembly of the International Space Station. Since December 1998, 248 spacewalks have been done at the International Space Station.

Since the beginning of the space era many spacewalks have been done by both the USA and Russia. The first ever spacewalk or Extravehicular Activity (EVA) was performed on the 18th March 1965 by Russian cosmonaut Alexei Leonov. IMAGE: Story Musgrave, courtesy NASA.

30th April 2015

The NASA spacecraft MESSENGER slams into Mercury traveling approximately 14,080 kilometres per hour in a controlled crash gouging a new crater about 16 metres wide in the planet’s northern terrain. INfor poster below courtesy of NASA.

This violent end was inevitable for MESSENGER, which had been orbiting Mercury since March 2011 and had run out of fuel. Launched on the 3rd August 2004 MESSENGER was the first spacecraft ever to orbit the innermost planet. Among its achievements the mission determined Mercury’s surface composition, revealed its geological history, discovered details about its internal magnetic field, and verified that its polar deposits are mainly water-ice.

BORN

28th April 1774

Francis Baily.

English astronomer. Most famous for his observations of "Baily's Beads" seen during an eclipse of the Sun. The phenomenon, which depends upon the irregular shape of the moon's limb, was so vividly described by him as to attract an unprecedented amount of attention for the total solar eclipse of 8th July 1842. He was also a major figure in the early history of the Royal Astronomical Society, as one of its founders and president four times.

The lunar crater Baily is named in his honour. This stunning image showing Baily's Beads during a total solar eclipse visible from ESO's La Silla Observatory on 2 July 2019 was taken and compiled by P. Horálek/ESO.

6th April 1890

André-Louis Danjon.

French astronomer noted for his important developments in astronomical instruments and for his studies of the Earth’s rotation. Danjon devised a method to measure "earthshine" on the Moon using a telescope in which a prism splits the Moon's image into two identical side-by-side images. He recorded the measurements from 1925 until the 1950’s using his method, now known as the Danjon Scale, on which zero equals a barely visible Moon. He served as president of the International Astronomical Union from 1955 to 1958 and retired from academic life in 1963.

14th April 1896

Priscilla Fairfield Bok.

American astronomer and wife of Dutch-born astronomer Bart Bok, Director of Mount Stromlo Observatory. Their marriage accompanied four decades of their close scientific collaboration, in which it was said "it is difficult and pointless to separate his achievements from hers". The Boks displayed great mutual enthusiasm for explaining astronomy to the public. They co-authored a number of academic papers on star clusters, stellar magnitudes, and the structure of the Milky Way galaxy. Priscilla Bok is commemorated by the asteroid 2137 Priscilla, named following her death.

The Boks are jointly commemorated by a 43-kilometre diameter crater on the far side of the Moon and by an asteroid discovered in 1975, 1983 Bok. Two Priscilla and Bart Bok Awards are jointly awarded each year by the Astronomical Society of the Pacific and the American Astronomical Society to astronomy-related projects in recognition of the Boks' advocacy for astronomy education and work in public outreach. The Australian National University awards the Priscilla Fairfield Bok Prize to a female third-year science student each year