September 25 – Discovery of Asteroid 203 Pompeja (1879)

Asteroid 203 Pompeja was discovered on September 25th 1879 by our old workaholic friend, the German-American astronomer Christian Heinrich Friedrich Peters. There isn’t much to say about it except it’s about 116 km across, and completes one orbit of the Sun every four and a half Earth years. Peters made all 48 of his asteroid discoveries, between 1861 and 1889, from the Litchfield Observatory at Hamilton College, Clinton, NY. Unfortunately it has since burnt down.

Pompeii (photo by me)
Pompeii (photo by me)

Which brings me subtly to the fact that Pompeja was named after the town of Pompeii, and given a suitably asteroidal name by changing the ending (for some reason they sound better if they finish with an “a”). Pompeii is an amazing place; you really should go.

Aphelion 3.376 AU
Perihelion 2.082 AU
Orbital period 4.51 years
orbital speed 18.03 km/second
Semi-major axis 2.729 AU
Eccentricity 0.237
Inclination 10.921°
Longitude of ascending node 97.251°

(epoch – Jan 30 2005)

September 24 – Discovery of Asteroid 318 Magdalena (1891)

Asteroid 318 Magdalena, discovered on September 24th 1891 by Auguste Charlois, is a main belt asteroid of about 105 to 106 km diameter, of unknown composition. The reason the name was chosen remains officially a mystery, but Charlois was working in Nice, to where Mary Magdalene was said to have travelled, and he was born in Provence, which has a very strong connection with Mary M., so I’m using that as a good enough reason to include a painting.

St Mary Magdalene Preaching in Marseille (Dutch, 1500 – 1520)
Aphelion 3.461 AU
Perihelion 2.927 AU
Orbital period 5.71 years
orbital speed 16.67 km/sec
Semi-major axis 3.194 AU
Eccentricity 0.084
Inclination 10.641°
Longitude of ascending node 161.671°
Argument of Perihelion 300.312°

(Epoch – Jan 20, 2005).

ALSO TODAY . . . .
1964 – Launch of Kosmos 46 from the Baikonur Cosmodrome. Kosmos 46 spent 8 days in orbit, taking in the view and photographing it, before returning a capsule of film by parachute.

September 23 – Discovery of Neptune (1846)

Officially, Neptune was discovered visually on September 23rd 1846 by Johann Galle, but its existence had been proposed by Alexis Bouvard years before, and its position was predicted by Urban Le Verrier on August 31st 1846, and by John Couch Adams a couple of days later.  James Challis at the University of Cambridge was also in the running, and observed Neptune twice before the discovery was announced, but failed to realise what was going on.  And Galileo had seen and noted Neptune himself, but even he had no idea what it was.

Neptune from Voyager 1 (image credit: NASA)
Neptune from Voyager 1 (image credit: NASA)

The first suggestion for a name for this new planet came from Galle, who thought Janus might be a good idea, after the two-faced Roman god of beginnings, from whom we get the name of the first month of the year.  Challis, no doubt anxious to make up for being beaten to the finishing tape, suggested Oceanus, whose children we have been meeting all year in these pages in the guise of asteroids.  Oceanus married his sister Tethys, and their children numbered at least three thousand, which, as they were immortal, might not have put as much of a strain on Tethys’ plumbing as I might imagine, because I have no idea how long it took them to complete their family.

Le Verrier was the first to suggest naming the new planet Neptune, the Roman god of the sea, and appropriately a brother of Jupiter and Pluto (he also suggested, modestly, Le Verrier, but this idea didn’t gain much support outside France).  The name is used almost universally, although as Neptune was the Roman equivalent to the Greek Poseidon, Greece is, as far as I’m aware, the only western country to use that name instead.

Neptune is a small giant (yes, I know what I just said).  It is 17 times more massive than Earth, but only about 5% as massive as Jupiter.  It is similar in composition to Uranus, and the two of them, while still coming under the “gas giant” umbrella, are sometimes also referred to as “ice giants”.

As with the other giants, Neptune has a ring system, but not one that’s going to be used as a backdrop to an episode of Star Trek anytime soon.  The rings are fairly thin, and few enough in number to have been named after some of the players in Neptune’s discovery (the Adams, Le Verrier, Lassell, Galle and Arago rings).

Neptune's Rings (image credit: NASA)
Neptune’s Rings (image credit: NASA)

At last count Neptune was known to have fourteen moons, all named after water deities.  I’ll just briefly mention that the biggest are Triton (way bigger than the rest at 2,700+ km diameter), Proteus, Nereid, Larissa, Galatea and Despina, but as all fourteen will probably be turning up in these pages over the next twelve months, we will leave it at that for now.

Just as an aside, it has been speculated that in the dim and distant past of the solar system there might have been a fifth gas giant, which was flung out of orbit by a strong gravitational kick from Jupiter or Saturn.

ALSO TODAY . . . .

1791  –  Birth, in Hamburg, of Johann Franz Encke, comet hunter, and expert at predicting when they were going to return. Encke also has a gap in Saturn’s rings named after him, in recognition of his observations of that planet.

September 22 – Discovery of Asteroid 57 Mnemosyne (1859)

Discovered on this very day in 1859 by Robert Luther, 57 Mnemosyne is a main belt asteroid of about 113km across, sweeping round the Sun at 16.7km/s,  and taking about five and a half years to complete one orbit. Mnemosyne is a stony “S” type asteroid, with an albedo of 0.215. S types are generally brighter than most, with Iris able to reach +7.0 at opposition.

Mnemosyne was a titaness (a daughter of Uranus and Gaia),  and was mother of the nine Muses (Zeus was the father, and somehow managed to persuade Mnemosyne that they needed to sleep together for nine nights to get the job done).

It is from Mnemosyne that we get the word mnemonic.

1862  –  Asteroid 75 Eurydike discovered by C H F Peters.

Orpheus and Euridice, by Christian Gottlieb Kratzenstein.
Orpheus and Euridice, by Christian Gottlieb Kratzenstein.

1878  –  Asteroid 190 Ismene, a member of the Hildian family, discovered by C H F Peters. The family are named after asteroid 153 Hilda.

1884  –  Asteroid 242 Kriemhild discovered.

2004  –  Planetoid 120347 Salacia discovered.  Salacia has an incredibly high number, but is significant because, as you will have noticed, I used the word “planetoid”, indicating it isn’t one of my normal day-to-day asteroids.  This particular Kuiper belt object is estimated to be 850 km (530 miles) in diameter.

September 21 – Discovery of Asteroid 149 Medusa (1875)

Henri Joseph Anastase Perrotin discovered today’s first asteroid, 149 Medusa, on September 21st 1875, at which time I believe he was working at Toulouse Observatory. His name is quite impressive,  so his discoveries are normally just credited to J Perrotin.

Medusa, despite being a bright stony asteroid, was a good catch for Perrotin, as it was the smallest to have been found at the time.


Medusa, of course, was the hideous female gorgon with snakes for hair who turned to stone anyone who met her gaze. She was one of three sisters (the others being Stheno and Euryale) who were the children of the marine deitiesPhorkys and Keto. Medusa was killed by Perseus, who then presented her head to Athene to attach to her shield. The word gorgon, incidentally, comes from the same root as the Sanskrit word “garg”, meaning a monster (from the noise they generally make).

Twelve years later, on September 21st 1887, Johann Palisa discovered 269 Justitia, a much larger main belt asteroid which was named after the Roman goddess whose Greek equivalent was Themis.

Themis, the personification of divine law and order, was one of the original twelve Titans, descendants of Gaia and Uranus, who ran the world until the Olympian gods showed up and overthrew them.

September 20 – Launch of Surveyor 2 (1966)

Today we mark the launch of Surveyor 2 from Cape Kennedy in 1966, headed for Sinus Medii, but which crashed at or near the crater Copernicus three days after launch, following a spin caused by a faulty thruster.

Model of Surveyor 2. (Photo credit: NASA.)

The purpose of Surveyor 2 was fairly simple. It was a flying camera, designed to image the lunar surface, and possibly perform a “lunar bounce” (basically, fire up the engines to jump up and down on the Moon to test the surface consistency). This was needed as part of the preparations for manned NASA missions to the Moon.


1979 – Launch of HEAO-3

1969 – Discovery of comet 67P Churyumov-Gerasimenko.

September 20 – Launch of HEAO-3 (1979)

Two and a half tonnes of HEAO-3, the last of its kind, were sent 486 kilometres in a generally upwards direction on top of an Atlas-Centaur launch vehicle on this day in 1979, on a planned 6 month mission, which eventually stretched to 21 months, to study x-rays, gamma rays and cosmic rays. HEAO stands for High Energy Astronomy Observatory.

Launch of HEAO-3 (image credit: NASA)
Launch of HEAO-3 (image credit: NASA)

HEAO-3 carried three experiments, described very briefly below:

1) The High Resolution Gamma Ray Spectrometer could have had an even longer name, as it was designed to study x-rays as well. Its purpose was to perform an all-sky survey, looking for x- and gamma-rays within a certain energy range.

2) The Cosmic Ray Isotope Experiment, whose primary purpose was to measure the isotopic composition of cosmic ray nuclei, as part of the drive to better understand the nature and propagation of cosmic rays.

3) The Heavy Nuclei Experiment did exactly what it said on the tin. It searched for heavy (and so-called super heavy) nuclei in cosmic rays.

So, here we are, 40 years later, and we still don’t quite understand how, why and where cosmic rays originate. But at least we’ve sorted one problem out: we know they’re not rays.

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ALSO TODAY . . . .

1966 – Launch of Surveyor 2.

1969  –  Discovery of comet 67P Churyumov-Gerasimenko.

September 19 – Discovery of Asteroid 48 Doris (1857)

Asteroid 48 Doris is a large main belt asteroid, and one of two to be spotted on September 19th 1857 by Hermann Goldschmidt.

The Doris after whom the asteroid was named was an Oceanid (a daughter of Oceanus and Tethys).  She had one son and fifty daughters, collectively known as the Nereids after their father Nereus.  She was Achilles’ grandmother.

Doris and Hippocamp

Today’s accompanying visual aid shows a rather sour-looking Doris riding a hippocamp (literally “horse monster” in Greek).


September 19 – Birth of Astronomer C H F Peters (1813)

Christian Heinrich Friedrich Peters  was born in Koldenbüttel (which was in Denmark at the time) on September 19th 1813, and became a big name in asteroid spotting, finding 48 in all, which makes him second in the all-time list of visual asteroid discoveries after Johann Palisa.

Peters was a bit of a radical in his youth, and while living in Italy his attempts to avoid the attentions of the authorities ended up with his fleeing to Turkey, where he made the acquaintance of the American ambassador, and before long found himself across the Atlantic mixing with the Harvard scientific community, and speaking in front of the American Association for the Advancement of Science in Rhode Island.

C H F Peters

Peters settled down at Hamilton College in Clinton, NY, as professor of astronomy, and as we have been hearing in this blog at irregular intervals all year, he made good use of their large 13½ inch refractor, working on sunspots by day and looking for asteroids at night.  I’m not sure when he slept.

His work was greatly aided by a supplement added to his rather meagre salary by a local businessman, who had the college observatory re-named after himself in return (to the Litchfield Observatory).  

Peters discovered his last asteroid, 287 Nephthys, at the age of 76, less than a year before his death.  He died on his way to the observatory, on July 19th 1890.



September 18 – 375 Ursula / 1965 S1 Ikeya-Seki

Comet C 1965 S1 Ikeya-Seki was first spotted on September 18th 1965 by Kaoru Ikeya and Tsutomu Seki, observing independently of one another. At magnitude -10 it was visible in daylight, and has earned the name The Great Comet of 1965.

Ikeya-Seki (photograph by Maynard Pittendreigh)
Ikeya-Seki (photograph by Maynard Pittendreigh)

Ikeya-Seki is one of a group of over-performers known as the Kreutz Sungrazers. The group also contains the Great Comets of 1843 and 1882, and is thought to comprise fragments of a huge parent comet that broke up in 1106.

The photograph above by Carolina astronomer (and Presbytarian minister) Maynard Pittendreigh might look a little dated to the Hubble generation, but to me it’s just fabulous.  It was probably all accidental, and he might have been going for a perfect shot, but I love the star trails, the scratches, the unidentified smear in the centre, and the telegraph wires.   It wouldn’t look out of place in a futuristic film from the early twentieth century, or a Bogus Blimp video.

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“Cool Jovian-mass” extrasolar planet MOA-2007-BLG-400Lb discovered today in 2008 in Sagittarius by Subo Dong and others.

Asteroid 375 Ursula is a fairly bulky main belt asteroid (approx 216 km diameter) discovered by Auguste Charlois on September 18th 1893. Ursula is another one of his finds with no readily apparent reasoning behind the name (you may recall 298 Baptistina from September 9th). If I could only find out on what date the naming happened, and maybe who came up with “Ursula” (it isn’t always the discoverer) I might get somewhere.

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