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)

May 25 – Launch of Skylab 2 (SL-2)

Skylab 2, launched today in 1973, was the first manned mission to NASA’s orbiting Skylab space station, prior to setting a new record of 28 days for the longest time spent in space (back in those days it was a lot more about setting records to get one over on the Russians than it is now). The actual Skylab station had already been launched, unmanned, on May 14th, in what was to be the final mission of the gigantic Saturn V rocket.

The Skylab Orbiting Space Station (image credit: NASA).

The crew comprised three astronauts; a famous veteran and two rookies. Flight commander, Charles “Pete” Conrad, third man on the Moon, was on his fourth mission, pilot Paul Weitz was making the first of his two (the other would be on the maiden voyage of the shuttle Challenger), and Joseph Kerwin was on his only venture beyond the atmosphere (which made him the first physician in space).

The crew of SL-2 (image credit: NASA).Fb

Following their launch atop a Saturn 1B, at 13:00 UTC, the crew took less than a day to reach Skylab, after which they set about trying to minimise the impact of the damage the staion had sustained at launch. It was missing its micrometeorite shield and part of the solar power array. Also, the remaining solar panel was jammed by a strap, possibly from the meteorite shield.

A partially deployed solar array, and the errant strap preventing it from unfurling (image credit: NASA)

Fortunately, it was known there would be a few issues before the crew lifted-off, so launch was delayed by ten days to allow for training on how to conduct repairs in orbit. It took some doing (they almost reached double figures in docking attempts, and had to use a foldable parasol to protect parts of the already blistered station from overheating) but eventually Skylab was brought up to a level that would allow future mission to be less stressful.

Skylab 2 Mission Patch. Spot the not-so-deliberate mistake? (Image credit: NASA)

May 08 – Look What I Found

This isn’t actually anything to do with May 8th, but I’m off work following an operation, and the day has no previous blog entry.

My Dad moved house recently (long story, but I’m blaming it for the hernia that put me in front of this keyboard today). In amongst the dusty, massive pile of junk he deposited in the middle of my Mum’s garage floor was a toffee tin full of cigarette cards. And in that I found a small, yellowing notebook containing a series issued by the company W.D. & H.O. Wills called “Romance of the Heavens”, which I now know were issued in 1928.

Unfortunately the cover is missing, and my Dad hasn’t got a clue who was responsible for the book, which was obviously created with some care, and probably with the use of a razor blade by someone who these days would be deemed far too young to have access to one, but is now showing it’s age. All he knows is it wasn’t him, which I already guessed, because there are no steam engines in it.

The author has also decided to add dates to the sides of certain cards showing when various phenomena were observed (they were all in January 1949, suggesting the creator of the book was not the smoker of the cigarettes from 1928).

The later pages of the book have some basic seasonal maps of the sky cut from a magazine or book and pasted in, and brief writings about each of the eight (including Pluto, excluding Earth) planets, in the slightly quirky order Mercury, Mars, Jupiter, Saturn, Venus, Uranus, Neptune, Pluto. I like to think that at some point in the winter of 1948-49, the phrase “Sh*t, I forgot Venus!” could be heard in the North Staffordshire countryside.

I’ll end with a short, badly drawn table to show how much has changed since as recently as 1949. For some reason our writer doesn’t mention any moons of Neptune, even though one was already known (the second, Nereid, would be discovered just four months after the latest known date written in the book). here’s a summary of then and now:

Planet Known Moons
1949 2019
Jupiter 9 79
Saturn 10 62
Uranus 4 27
Neptune 1 14
Pluto 0 5

Not forgetting, of course, that Jupiter, Uranus and Neptune have also been shown to possess ring systems.

Created May 07, 2019.

December 30 – Launch of RXTE

December 30th seems to be a thin day astronomically, but I did manage to find, in 1995, the launch of the Rossi X-Ray Timing Explorer from Cape Canaveral.  Bruno Rossi, after whom the satellite was named, was the discoverer of the first source of x-rays beyond the Sun.

Artist's Impression of RXTE
Artist’s Impression of RXTE

Over a sixteen year lifespan, RXTE did exactly what its name suggests: it timed variations in emissions from x-ray sources using three experiments (a proportional counter array, theHigh Energy X-ray Timing Experiment, and an all-sky monitor).

Also today, in 1924, Edwin Hubble announced to the world that the Milky Way is not the only galaxy.  Using the 100-inch Hooker Telescope at Mount Wilson, Hubble was able to calculate the distance to Cepheid variable stars in the Andromeda Galaxy using a technique devised by Harvard astronomer Henrietta Swan Leavitt.  At the time, “spiral nebulae” were assumed to be patches of dust or gas within the Milky Way, but calculating a distance to Andromeda of approximately 860,000 light years changed the scale of the Universe for ever.


November 02 – Asteroid 13 Egeria

Annibale de Gasparis discovered today’s asteroid, 13 Egeria, in 1850, named some time later by Urbain Le Verrier in honour of an Italian nymph.

Egeria is, as usual, in the main belt, but is a G-type, not something we get in these pages every week.  G-types are similar to C-types, but are thought to contain phyllosilicates such as clays or micas.  Phyllosilicates get their name from their tendency to form sheets (phyllon is the Greek for “leaf”).

Following occultations of stars in 1992 and 2008 it was decided that Egeria is fairly circular, measuring approximately 200 km in diameter.  It was also one of the seventeen lucky rocks chosen to take part in a University of Hawaii search for satellites and dust rings around asteroids, but none were found.

Egeria Mourns Numa (Claude Lorrain)
Egeria Mourns Numa (Claude Lorrain)

The eponymous nymph shown above was a minor Roman goddess whose origin is unclear (we don’t even know for certain if she was a water nymph or a mountain nymph).   Her cult is known to have been celebrated at several sacred groves, though not usually on her own.   She provided prophecy in return for gifts of water or milk, and was able to divine the sometimes seemingly impenetrable omens sent by the gods.  Her relationship with Numa Pompilius, the supposed second king of Rome (after Romulus) was as a sort of counselor.  Numa supposedly wrote down her teachings and had them buried with him.  When they were discovered by peasants years later, according to Livy, they were thought to be so inflammatory in nature that the Senate had them burned.

1875   ⇒   Discovery of asteroids 152 Atala by the French optician/astronomer brothers Paul and Prosper Prosper Henry, and 153 Hilda by Johann Palisa.

1885   ⇒   Birth, in Nashville, of Harlow Shapley, the American astronomer who correctly estimated the size of the Milky Way, and where the Sun sits within it.  This was achieved using RR Lyrae variable stars, a class of very handy “standard candles” whose luminosity can be used to estimate distances within our galaxy.

October 09 – Asteroid 109 Felicitas

Asteroid 109 Felicitas was discovered on October 9th 1869 by Christian Heinrich Freidrich Peters.  It’s in the main belt, fairly large at about 90 km wide, and dark.   It was named after the Roman goddess of luck, success, fertility, good fortune, and a host of related concepts.

Roman inscription: Lady Luck Lives Here.
Roman inscription: Lady Luck Lives Here.

On October 9th 1873 German physicist Karl Schwartzschild was born in Frankfurt.  He was the man who came up with the formula for the event horizon known as the Schwartzschild Radius, which defines the size of a black hole.  Very simply, it’s the size an object of a certain mass has to be so that nothing (not even light) can’t escape from its gravitational pull.  So anything smaller than its own Schwartzschild radius can’t be seen.  As an example, if the entire mass of the Earth were to be compressed into a sphere with a radius of nine millimetres, it would become a black hole.  The Sun, however, would only need to be compressed to about 2 miles.  So in this particular case, size would appear to be important.

August 9th, 1604, was a very important day for naked eye astronomy.  It was the last time that a supernova in our galaxy was definitely observed by the naked eye.  Kepler’s Supernova, as it is usually known, occurred in the constellation Ophiuchus, and was spotted by Johannes Kepler, who was in northern Italy at the time.   There have almost certainly been at least two subsequent supernovae in the Milky Way, but there are no records in existence to show that either was seen with the naked eye.

One launch to mention quickly: HETE 2, (High Energy Transient Explorer) launched today in 2000 from a Pacific atoll, to detect gamma ray bursts and perform an X-ray sky survey.