January 04 – Discovery of Asteroid 86 Semele (1866)

Making his first and last appearance in the field of asteroid discovery today is German astronomer Friedrich Tietjen.  On January 4th 1866, from the New Berlin Observatory (the place where Neptune was discovered) he found asteroid 86 Semelea large, dark, C-type body of about 120 km wide, in the main belt.

Aphelion 3.761 AU
Perihelion 2.467 AU
Semi-Major Axis 3.114 AU
Orbital Period 5.5 years
Inclination 4.822°
Eccentricity 0.208

Semele is named after the daughter of Cadmus and Harmonia (asteroid 40).  She was the mother of Dionysus.  Zeus was the father, as usual (where did he find the time?).

Jove and Semele (S Ricci)
Jove and Semele (S Ricci)

Today’s picture is of Jove and Semele, by the Italian artist Sebastiano Ricci, a man whose private life would not have shocked the average Greek or Roman god.  He was imprisoned at a young age when, in an attempt to avoid marriage, he tried to poison a young woman he had made pregnant.  He did eventually marry her, but I doubt there was much trust in the relationship.

1797  –  Birth of Wilhelm Beer, moon mapper and accurate predictor of the rotation of Mars (only about a tenth of  a second away from today’s value).

1876  –  158 Koronisa 35.4 km diameter S-type main belt asteroid, discovered by Russian astronomer Viktor Knorre.  Koronis is the head of the Koronidian asteroid family, created from a collision about 15 million years ago.  No known member of the family is particularly large (the biggest, 28 Lacrimosa, is only about 41 km across), but there are a lot of them, with over 300 known members.

1908  –  Discovery of asteroid 654 Zelinda by August Kopff, from the Heidelberg-Königstuhl State Observatory in Germany.  Zelinda is in the main belt, and measures somewhere in the region of 130 km across (opinions vary).  Zelinda was named by the Italian astronomer Elia Millosevich, in honour of the daughter (again, opinions vary, with The Dictionary of Minor Planet Names saying she was his sister, but she was thirty years younger than him, so I’m going with daughter) of mathematician and politician Ulisse Dini (a friend of Millosevich).

2010  –  Exoplanet Kepler-7b, a “hot Jupiter”, discovered by NASA’s Kepler spacecraft.  The planet was recently found to have a surprisingly predictable weather.

January 02 – Launch of Luna 1 (1959)

Luna 1 was launched by the USSR (Russia) on January 2nd 1959, and was intended to be the first spacecraft to impact the Moon. Unfortunately for the Soviet scientists involved in the program an error back on the ground caused the rocket carrying it to burn for too long, changing the trajectory and sending the payload hurtling past the target at about 6000 km distance. The result was that on January 4th 1959, Luna 1 entered a heliocentric (around the Sun) orbit between Earth and Mars, becoming, I suppose, the first artificial planet. It’s still up there, completing an orbit of the Sun every 450 days, and will probably remain there for a very long time.

Replica of Luna 1 (image: RIA Novosti archive, image #510848 / Alexander Mokletsov / CC-BY-SA 3.0)
Replica of Luna 1 (image: RIA Novosti archive, image #510848 / Alexander Mokletsov / CC-BY-SA 3.0)

Despite missing the target, Luna 1 did provide some useful information. It was able to measure the solar wind for the first time, and discovered that the Moon has no detectable magnetic field.

Our photograph today is of a replica of Luna 1, so you should probably ignore the huge stalk sticking out of the bottom.

1905 – Discovery of Jupiter’s eighth largest moon, Elara, by Charles Dillon Perrine. For some reason Elara didn’t receive its present name until 1975.

December 06 – Launch of Pioneer 3

Launched from Cape Canaveral on December 6th 1958, Pioneer 3 was supposed to be a lunar flyby. Unfortunately that didn’t happen, owing to a problem with its booster rocket, but the craft did manage to reach a distance from Earth of about 63,000 miles, and used its Geiger-Müller tubes to gather useful information about the Van Allen radiation belt.

Pioneer 3 (image: NASA / JPL)
Pioneer 3 (image: NASA / JPL)

Pioneer 3 ended its one day flight by burning up over Africa.

It isn’t easy to get a sense of scale on some of these artist’s impressions, such as the one above, with Pioneer 3 optimistically shown flying over the lunar surface, so here’s a NASA photo of the probe being prepared:

1888 – Birth of comedian and astronomer Will Hay in Stockton-on-Tees, North East England. In 1933 he discovered a Great White Spot on Saturn in August 1933 (note: it’s “a” not “the” Great White Spot, as there have been several observed over the past century). At his home in Norbury, South London, Hay built his own observatory to house his 1895-vintage 12.5 inch Newtonian reflector and the 6-inch refractor he used to discover the white spot.

1893 – Discovery of asteroid 378 Holmia by Auguste Charlois (the name is the Latin for Stockholm).

1998 – Launch of the Submillimeter Wave Astronomy Satellite (SWAS). One of NASA’s SMEX (Small Explorer) missions, SWAS was intended to have an operational life of two years, but managed to stretch to six, studying the cores of interstellar clouds to help our understanding of what they are composed of, and how they cool and collapse to form stars.

Finally, we can’t let the day go by without saying happy birthday to the late, great Johann Palisa, born in 1868 in Troppau (now in the Czech Republic). Over the course of about 50 years he discovered 122 asteroids, and is mentioned a helluva lot in this blog. Palisa persisted in making all his asteroid discoveries visually, even though Max Wolf was able to streak past his total with ease by using photography.

An Apollo photo of the lunar crater “Palisa” (image: NASA).

October 06 – Discovery of Asteroid 299 Thora (1890)

Smallish asteroid 299 Thora is a fairly typical main belter, discovered on October 6th 1890 by Johann Palisa. It is about 17 km wide, and zooms around the Sun every 1,387 days at 19 km/second.

If you have access to a reasonably hefty telescope you might want to look for Thora. It’s in Pisces for the next few months (late 2019) , before drifting off in the direction of Taurus. Check out In-The-Sky.org or a similar site for detailed location advice.

Thor wades through a river while the æsir take the bridge, by Lorenz Frølich

The name Thora was chosen by a Professor Schlieber of Berlin, after the Germanic and Norse god of thunder and lightning, Thor. According to Norse legend, Thor was the son of Odin, and husband of Sif (although, as with the Greek gods, this didn’t stop him fathering children by other women). Thor, as you are probably aware, carried a hammer capable of flattening mountains, and had Thursday named in his honour.

So, if you know anyone named Thora, tell them they can blame it on their pagan Viking parents.

September 09 – Discovery of Asteroid 61 Danaë (1860)

Asteroid 61 Danaë  –  discovered September 9th 1860. Danaë is a large, rocky S-type asteroid of about 80 km diameter in the main belt, rotating every eleven and a half hours. It was discovered from Paris by Hermann Goldschmidt, but named by fellow asteroid hunter Robert Luther after the mother of Perseus.  The father was, as usual, Zeus, who impregnated her in the guise of a shower of golden rain (no comment).

Danaë, in playful mood.


Asteroid 56 Melete discovered, 1857.

Asteroid 189 Phthia discovered, 1878.

Asteroid 297 Caecilia  discovered, 1890.

Asteroid 298 Baptistina discovered, 1890.

June 20 – Georges Lemaître

The Belgian priest and astronomer luxuriating in the just-about-tweetable name of  Monseigneur Georges Henri Joseph Édouard Lemaître died on June 20th 1966.

A ripple of controversy surrounded our subject in 2011, when it was suggested that the Hubble constant should more properly be attributed to Lemaître, rather than the eponymous Edwin.  It had been said by some that Hubble, or someone in his circle, edited a paper by Lemaître in an inventive way, so as to make it less than obvious that Lemaître had got to the discovery of an expanding universe before Hubble.  It later turned out, however, that it was Lemaître himself who had omitted vital elements of the paper, possibly due to a linguistic misunderstanding.

Lemaître was an early pioneer of using Einstein’s equations to solve cosmological problems (Einstein himself wasn’t so sure they ought to be).  He was the first to estimate the Hubble constant, as already mentioned, and to  derive Hubble’s Law.   And just in case you thought that was enough, he was also the first person to propose a Big Bang type theory to describe the birth of the universe.

Monseigneur Lemaître
Monseigneur Lemaître

I won’t try to explain Hubble’s law here (because I probably can’t).  It can be expressed as a very simple equation to explain a very complicated situation, and if I start I might not be able to finish.  Let’s just settle for saying that the rate of movement of galaxies away from the Earth is proportional to their distance from the Earth and from each other, and it’s the Hubble constant that gives us the magic number that let’s us prove the proportionality.

Lemaître was extremely important for someone most of us have never heard of, and was honored all over the place while alive.  He was voted 61st in a survey of the 100 greatest Belgians in 2005.

June 04 – 456 Abnoba

Main belt asteroid 456 Abnoba was discovered on June 4th, 1900, by Max Wolf and F K A Schwassmann. It is an S-type asteroid of approximately 400m diameter,  and the JPL Small Body Database tells me it has an absolute magnitude of 9.1 and a rotation period of 18.281 hours.

Max Wolf
Arnold Schwassmann

Abnoba was a Celtic / Gaulish (I had to override the spellchecker here, to remove the word ‘goulash’) goddess of the hunt, worshipped principally in the Black Forest area, and associated with the Roman goddess Diana. She was also a goddess of waterways, and it is probable that her name is derived from the same Celtic root, abon, as the Welsh word for river, afon, and the name of a famous English river, the Avon.

Today’s final image shows an altar dedicated to Diana Abnoba from the Badenweiler Roman Baths, Germany. (Image: Wikimedia Commons).  The popular spa resort of Badenweiler was where the playwright Anton Chekhov arrived in June 1903 to help ease the symptoms of his tuberculosis.  He died there on July 15th 1904.

If you’re now in the mood for a goulash goddess, there’s a recipe on Nigella Lawson‘s website.


May 31 – Discovery of asteroid 892 Seeligeria

A lesson in how to crowbar a name into an asteroid, 892 Seeligeria was discovered on May 31st, 1918, by Max Wolf, and named after German astronomer Hugo Hans Ritter von Seeliger.

Hugo von Seeliger.

Seeligeria is in the main asteroid belt, is approximately 38 km (23.6 miles) in diameter and has a year lasting almost 6 Earth years.  On average it is about 3.2 AU from the Sun, although it’s elliptical orbit means it can be as close as 2.9 AU, and as far away as 3.5 AU.

Seeligeria is a member of the Alauda family of more than 1,200 known carbonaceous asteroids, containing a variety of interesting names, including  3325 TARDIS, which hardly needs an introduction, likewise the great violonist 52344 Yehudimenuhin and the alma mater of Anton Checkov and Mikhail Gorbachev, 6355 Univermoscow.

Von Seeliger (1849 – 1924), was a prominent astronomer in his day, and also professor of astronomy at the University of Munich, where one of his PhD students was Karl Schwartzschild, who gave us the Schwartzschild radius (I’m not going to try to define this here, so I have included a rare thing in these blogs: a hyperlink).


1918: Asteroid 893 Leopoldina.  It was not unusual for the likes of Max Wolf to discover two asteroids in a day, and today is one of those days.  893 Leopoldina is another main belt asteroid, also 38 km in diameter, but not a member of the Alauda family.  Leopoldina is named in honour of the Academy of Sciences Leopoldina, in Halle, Germany.

1975: The European Space Agency is formed.

2008: Launch of space shuttle mission STS-124 to the International Space Station.  The crew of seven took with them a substantial part of the Japanese Experiment Module (the biggest single ISS module), a Buzz Lightyear figure, and spare parts for a malfunctioning toilet.  Spaceflight isn’t all glamour.


May 29 – Discovery of M10, 1764

The globular cluster Messier 10, discovered by Charles Messier, unsurprisingly, was described by him as a “nebulous patch without stars” on May 29th, 1764, after which he could relax and ignore it, safe in the knowledge that it was not a comet, and therefore unworthy of further attention.  M10, also known as NCG 6254, is in the large, equatorial constellation of Ophiuchus, “the serpent bearer”, and is about 80 light years across, meaning it should occupy an area of the sky two-thirds that of the full Moon.  This sounds impressive, but if you find it in the average telescope it won’t look anything like that big, because you will only be able to see the core.

Messier 10 (Image credit: NASA / STScI / ESA)

This beautiful photograph was taken by the Hubble Space Telescope, and shows the core of M10, at a distance of about 15,000 light years.

Yet another asteroid day.  Today we have 72 Feronia, discovered on May 29 1861 by the German-American astronomer Christian Heinrich Friedrich Peters, who went on to find another 47, so he must deserve a birthday shout-out on September 19.

Feronia is a large, dark main belt asteroid, about which there isn’t much to say except that it has a diameter of about 86km, a rotation period of a little more than 8 hours, and takes over 3 years to orbit the Sun.

Feronia’s namesake is a Roman goddess, variously associated with fertility, health and wildlife. She was apparently very popular among plebeians, and as I’m one myself I must remember to tweet her feast day on November 13.

Marble head, suspected to be that of Feronia (Museo Civico Rieti, Italy).

1889  –  Discovery of asteroid 284 Amalia  by Auguste Charlois.

Updated: May 2019.

May 28 – Discovery of Asteroid 99 Dike

Asteroid 99 Dike was the first of many asteroids (and the occasional comet) to be discovered by Alphonse Borrelly (1842-1926) from his Marseilles observatory. This one was spotted on May 28th 1868.  I have very little to say about it, except that I think it should be pronounced die-kee rather than dyke or decay.

99 Dike has been shown, like three-quarters of all known asteroids, to be a carbonaceous “C-type”, meaning it has a high carbon content, which also means it is dark in colour.  According to the JPL Small Body Database, Dike is about 67km across, takes 1,589 days to orbit the Sun, and has an absolute magnitude of 9.43.

Dike Astrea was a daughter of Zeus and Themis, and was the goddess in charge of justice and fair judgement in the mortal world (her mother had the same responsibility over the immortals).

Dike Astrea (credit : GearedBull at Wikipedia)