March 17 – Jim Irwin

March 17th 1930: astronaut Colonel James Benson Irwin, USAF, born in Pittsburgh PA.

James Irwin (image credit: NASA)

James Irwin (image credit: NASA)

In 1971 Irwin, Apollo 15 lunar module pilot, became the eighth man to walk on the Moon, spending over 18 hours on the surface.  He also, on his return, became one of the first people to be grounded, quite literally, for smuggling postage stamps into space.


1852  –  Asteroid 16 Psyche was discovered on March 17th 1852 by Annibale de Gasparis.  Psyche is a large asteroid, about 200 km in diameter, accounting for about 1% of the mass of the entire asteroid belt.  It’s an M-type asteroid, probably mostly nickel and iron.

Cupid and Psyche (Van Dyck)

Cupid and Psyche (Van Dyck)

Psyche is named for a mythological princess, who caught the eye of the god Cupid.  The story is told by Lucius Apuleius in The Golden Ass.

In early 2017 NASA announced plans to  send a probe to Psyche in 2023, as part of their Discovery Program, the main reason being that, as a metallic asteroid, it represents one of the few classes of objects in our neighbourhood that haven’t yet been visited.


1899  –  Saturn’s moon Phoebe discovered by American astronomer W H Pickering.  It, too, is about 200 km in diameter, and may be a captured centaur from the Kuiper belt.  We have some spectacular photographs of Phoebe following the visit of the Cassini spacecraft in 2004.

Phoebe (image credit: NASA)

Phoebe (image credit: NASA)

 


 

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August 08 – Happy St Dominic’s Day!

Today is the feast day of St Dominic, the patron saint of astronomers.

St Dominic (Claudio Coello, c.1685)

St Dominic (Claudio Coello, c.1685)

Dominic de Guzmán was born in Spain in 1170, and became founder of the Dominican order, which today numbers a relatively robust 6,000 or so friars.  It is thought he may have been an early member of the Spanish Inquisition (I bet you weren’t expecting that) and is actually seen in a painting by Peter Beruguette presiding over an auto-da-fé (a public act of penance by condemned heretics, popular with the Inquisition).

St Dominic is also indirectly and tenuously linked to the formation of Everton FC, a football club with its origins in the nineteenth century sporting ambitions of the St Domingo Methodist Church, Liverpool.

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The High Precision Parallax Collecting Satellite (HIPPARCOS) was launched today in 1989 by the European Space Agency, at the start of a successful four year career.  As well as being an only slightly tortured acronym, Hipparcos is a surprisingly accurate spelling of the Greek astronomer (but he’d be Turkish if he was born in the same town today) more commonly known as Hipparchus of Nicaea.  The homage is to his work on all kinds of trigonometric problems, including his insight into the precession of the equinoxes.  The greatest astronomer until Ptolemy, he is even suspected of devising a heliocentric (Sun at the centre) theory of the solar system, which he abandoned because it relied (correctly) on the orbits of the planets not being perfect circles.

The purpose of the Hipparcos mission was, very simply, to tell us where stars are, and where they are going relative to us.  Providing astronomers with a highly accurate frame of reference has allowed other, older astrometric measurements to be fine-tuned.  It has enabled us to calculate much better determinations for such things as the ages and masses of stars, and the rotation of the Galaxy.

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ALSO TODAY . . .

1991  –  Astronaut Jim Irwin (Apollo 15) died.

2001  –  Launch of the GENESIS spacecraft to collect a sample of the solar wind.

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