March 29 – Discovery of Asteroid 4 Vesta (1807)

Asteroid 4 Vesta, the brightest asteroid visible from Earth, and one of the larger, at about 530 km wide, was first spotted on March 29th 1807 by Heinrich Wilhelm Olbers. It is named after the Roman goddess of the home and hearth, who always had a fire burning in her temples as a reminder.  Vesta is the second most massive asteroid (after Ceres, which had been discovered the year before)  but is only the third biggest by volume (Pallas, also discovered by Olbers, five years earlier, takes second place).

Composite image of Vesta from the DAWN spacecraft (image credit: NASA)
Composite image of Vesta from the DAWN spacecraft (image credit: NASA)

Vesta was visited recently (July 2011) by NASA’s Dawn spacecraft, which took the above image (actually it’s a collection of many images stuck together). Observations show it to be an oblate spheroid, but irregularities in shape and the low mass mean it doesn’t qualify as a dwarf planet under the current naming rules.

 2002  –  Launch of the Reuvan Ramaty High Energy Solar Spectroscopic Imager (HESSI, or RHESSI) to study solar flares.

March 28 – Discovery of Asteroid 2 Pallas (1802)

Asteroid 2 Pallas was discovered on March 28th, 1802, by Heinrich Wilhelm Olbers, physician by day, astronomer by night, and the man after whom the Olbers Paradox (the one about why the sky is dark if the universe is infinite) is named.  He discovered Pallas while trying to locate Ceres, which had been discovered by Giuseppe Piazzi the previous year.

Pallas (from the Hubble Space Telescope). Image: NSAS
Pallas (from the Hubble Space Telescope). Image: NASA

Pallas is at the larger end of the minor planet scale,  being about 550 km wide on average (it isn’t round). It is a B-type body, one of the less common asteroid types. B’s are similar to the much more populous C-types, but with a greater albedo, and different a absorption lines in their spectra.

Statue of Pallas Athene above the Austrian Parliament Building in Vienna (image credit: Max Novara)
Statue of Pallas Athene above the Austrian Parliament Building in Vienna (image credit: Max Novara)

Pallas is named after the Greek goddess Athena (she was often referred to as Pallas Athena/Athene), goddess of wisdom, daughter of Zeus and Metis, owner of the Aegis, and friend of owls. Her Roman equivalent was Minerva.

On March 28, 1900, asteroid 454 Mathesis was discovered from Heidelberg by Friedrich Karl Arnold Schwassmann. Mathesis is a main belt asteroid of about 81.6 km diameter, having, apparently, a rather pleasing year of 1555.5 days, and an equally pleasing albedo of 0.0555. I wonder if that’s why it was named after mathematics?

Schwassmann was discoverer of 22 asteroids, but this was his first without the assistance of the even more prolific discoverer, Max Wolf .

 2009  –  Start of ISS expedition 19.

March 20 – Discovery of Messier 96 (1781)

The third of today’s three Messier objects is Messier 96. It was identified by Messier’s assistant Pierre Méchain, and is the largest member of the Leo 1 group (also known as the M96 Group). Unlike M95 (see last post) it has an asymmetrical structure and an off-centre nucleus, the result of gravitational interractions with other members of the group.


M96 is not easy to find. The photograph here was taken by the 8.2 metre Very Large Telescope (great name) at the European Southern Obsrvatory in Chile. You shouldn’t expect to see anything like this through your binoculars, because you will be disappointed.

March 20 – Discovery of Messier 93, 1781

Messier 93, NGC2447, was discovered on this day in 1781. This binocular object is an open cluster about 3,600 light years away, spanning approximately 10 light years, in the constellation Puppis. It was the last open cluster to be discovered by Charles Messier himself. M93 contains a good collection of blue giant stars, as well as quite a few red giants, possibly in clusters of their own. It’s hard to say how many stars a cluster contains, mainly because they get in each other’s way when you try to count them. This one has at least 80 identifiable members, but may well turn out to be several hundred strong.


March 19 – Discovery of Asteroid 326 Tamara (1892)

1892   –   Asteroid 326 Tamara, discovered March 19 1892 by Johann Palisa.  It is a C-type asteroid of about 93 km wide in the main belt, named after Tamar the Great, Queen of Georgia.

Queen Tamar, and her father, George III of Georgia.
Queen Tamar, and her father, George III of Georgia.

1892  –  Asteroid 332 Siri was also discovered on March 19th 1892, but by Max Wolf at Heidelberg.  It’s a fairly small object, about 40km wide.  The origin of the name is not known, and I haven’t been able to find any likely candidates.  Part of the problem, of course, is that, as with the aforementioned Tamara, and the next on this page, Isara, the name could have been altered to fit some perceived idea of what an asteroid’s name should sound like.

1893  –  Asteroid 364 Isara was discovered by Auguste Charlois.  It is a member of the large Flora family of S-type asteroids, which may be parents of the L chondrite meteorites.  The Isère river, from which this asteroid derives its name, flows from the Alps and joins the Rhone near Valence in southern France.

1919  –  Karl Wilhelm Reinmuth discovers asteroid 911 Agamemnon, a “Greek camp” Jupiter Trojan of approximately 83 km radius (making it probably the second biggest).

Originally posted 2015. Updated 2017.


March 18 – 136 Austria

Asteroid 136 Austria was discovered on March 18th 1874 by Austrian astronomer Johann Palisa.  Because it was his first discovery, he got a bit patriotic when it came to choosing a name, although he did stick to the convention of Latinising the name, rather than use Österreich or Oesterreich.

The Coat of Arms of Austria
The Coat of Arms of Austria

136 Austria is in the main belt, is about 40 km wide, and may or may not be an M-type.  A study by Clarke et al published in the Abstracts of the 25th Lunar and Planetary Science Conference suggest it may be more of an S-type.

March 17 – Birth of Jim Irwin, Astronaut (1930)

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)



March 16 – Caroline Herschel

Caroline Herschel was the sister of the more famous William.  She was born this day in 1750 in the German town of Hannover, but moved to London in 1772 to join her elder brother, after which she became a lean, mean, comet hunting machine, finding eight of them in eleven years.  She also discovered an impressive clutch of deep sky objects, mostly open clusters, and was awarded the Gold Medal by the Royal Astronomical Society.  After William’s death she moved back to Hannover, where she died in 1848.

Caroline Herschel
Caroline Herschel

Herschel wasn’t the tallest astronomer in history, and at 4 foot 3 inches she might possibly be the shortest person ever to find a comet (I need to check up on that).  Her diminutive stature was caused by a bout of typhus at the age of ten.  Her father sounds less than doting, and is reported to have told his fifth child that, because of the deformity caused by this illness, she would never marry.  Nice man.

March 15 – discovery of Asteroid 78 Diana (1853)

1853  –  Asteroid 78 Diana was discovered on March 15th, 1853 by Robert Luther, the German astronomer who discovered 24 asteroids. According to IRAS observations Diana is about 120 km across, a figure that matches quite well with the 116 km diameter obtained from observations of the occultation of star SAO 75392 in 1980.

Diana Hunting, by Guillaume Seignac.

Diana is named after the Roman goddess of the hunt, and her Greek equivalent, Artemis, will be turning up in these pages later in the year (discovered September 16th, 1868).

1873– Asteroid 118 Peitho discovered by Robert Luther. This main belt asteroid is about 47 km in diameter, and categorised as S-type. There are a couple of Peitho‘s in Greek mythology, with the most likely candidate for this naming ceremony being the goddess of seduction, an attendant of Aphrodite. Her Roman name, Suada, presumably shares a root with the Latin persuadere , the place from where we get the middle English word persuasion.