This one is a day overdue. I do a lot of these late at night. Perhaps I shouldn’t.
Main belt asteroid 46 Hestia was discovered on August 16th 1857 from the Radcliffe Observatory, Oxford, by Norman Robert Pogson (1829-1891). Hestia (Greek goddess of the hearth) is a “c type” body of about 124 km diameter. Pogson gave the honour of naming her to astronomer, coin collector, and veteran of the 1810-12 Siege of Cadiz, Admiral William Henry Smyth.
Hestia was one of eight minor planets discovered by Pogson, who also found time to make over fifty thousand observations for a Madras University star catalogue while working in India, discovering 134 stars along the way.
ALSO TODAY: 1873 – Discovery of asteroid 133 Cyrene. 1885 – Discovery of asteroid 249 Ilsa.
Prolific asteroid hunter Alphonse Borrelly discovered main belt asteroid 146 Lucina on June 8th, 1875. It was the fifth of his 18 asteroids, and is a dark, carbonacous asteroid, and fairly large, at around 131 to 132 km across.
The name is slightly ambiguous. Lucina is the name given to the Roman goddess of childbirth, but there are two of them. While it is usually an epithet given to the goddess Juno, it can also refer to Diana, as both of them were involved in the birthing business.
In 1982, observations of a stellar occultation by Lucina made at the Meudon Observatory in France and reported in the journal Icarus (vol 61, issue 2) recorded a secondary event, possibly caused by a small satellite. This satellite was estimated to have a diameter of about 5.7 km, and to be about 1600 km from the asteroid.
In 2003, the case for a satellite was strengthened by observations of the orbital motion of Lucina, published in the proceedings of the 34th Annual Lunar and Planetary Science Conference by Jean-Baptiste Kikwaya and others from the Vatican State Observatory. It’s not absolute proof, but it’s looking likely that 146 Lucina may not be alone.
June 5th, 1885marks the discovery of asteroid 248 Lameia by Johann Palisa. Lameia is a main belt asteroid of about 50 km diameter, of unknown spectral type. It’s strange that we can know some things about these rocks very precisely, and others not at all. For example, the JPL Small Body Database tells me that the orbital period (year) of 248 Lameia is 1418.617077981085 days. That’s quite precise.
Lameia takes its name from Greek mythology, as do most early asteroid discoveries. Lamia was a queen of Lybia who made the mistake of becoming one of Zeus’ lovers. The affair panned out in the usual fashion, with Zeus’ wife, Hera, finding out about it, and turning Lamia into a child-eating monster, also seen in some stories to seduce men in order to feed on their blood.
These character flaws may in part be why there is so much about Lamia on the internet. Or maybe it’s because she got her own character in the Final Fantasy franchise.
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 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.
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 .
Asteroid 28 Bellona was discovered by Robert Luther on March 1st 1854, three weeks before the start of the Crimean War, so the name was chosen to be topical (Bellona was a Roman goddess of war). Bellona is a large S-type asteroid of somewhere between 110 and 120km across.
An even larger S-type asteroid, at over 200km wide, is 29 Amphitrite, discovered on the same day, several hundred miles from Luther in Regent’s Park, London, by another German astronomer, Albert Marth. Marth was working at the time for George Bishop, the owner of a private observatory in the park. Bishop chose the name. Amphitrite was Marth’s only asteroid, but John Russell Hind, who we meet in these pages every so often, used Bishop’s 7″ refractor to greater effect to discover ten asteroids between 1847 and 1854. Unfortunately the observatory is no longer in Regent’s Park; the telescope was moved to his son’s residence in Twickenham after Bishop’s death, and then donated to an Italian Observatory.
In ancient Greek mythology, Amphitrite was a Nereid, and wife of Poseidon.
185 Eunike is a dark, large, carbonaceous main-belt asteroid, approximately 157 kilometres in diameter. It was discovered on March 1st, 1878 by Christian Heinrich Friedrich Peters, and named, in a politically motivated fashion after yet another Nereid, Eunike, whose name means ‘happy victory’. This is a reference to the Treaty of San Stefano, signed on March 3rd 1878 between the Russian Empire and the Ottoman Empire at the end of the Russo-Turkish War. The treaty led to the creation of an autonomous Bulgaria, became the central point of Bulgarian foreign policy, lasting until 1944, and led to the Second Balkan War and Bulgaria’s entry into World War I.
306 Unitas is another main belt asteroid, discovered by Elia Millosevich on March 1st, 1891. in Rome, and named by the director of the Modena Observatory in honor of the Italian astronomer Angelo Secchi. It is classified as an S-type asteroid. Unitas has a similar orbit to the Vesta family, but has been found to be unrelated to them.
1894 – 385 Ilmatar and 386 Siegena
385 Ilmatar is a large main belt asteroid discovered by Max Wolf on this day in 1894. Ilmatar is the virgin spirit of the air in Finnish mythology.
386 Siegena is another large, C-type asteroid. It, too, was discovered by Max Wolf in 1894. It is named after the city of Siegen in Germany.
1842 – Birth of Nicolas Camille Flammarion, astronomer and science fiction author, in Montigny-le-Roi, France.
1880 – Birth of Kenneth Edgeworth, the first person to propose the existence of what would eventually become known as the Kuiper Belt.
1965 – Launch of the experimental meteorological satellite Cosmos 58 by the USSR.
Today, as we have no “asteroid” discoveries to discuss, we’re going to have a crash course in a couple of groups of large flying things that used to be called asteroids, but are now commonly known as minor planets. The term refers to all sorts of things, and can be broadly defined as anything orbiting the Sun that isn’t a planet or a comet. The terminology, however, is confused and confusing, and unlikely to become any clearer as more bodies are discovered beyond the traditional confines of the Solar System. So nowadays you have to decide whether you’re talking about a dwarf planet, an asteroid, a trojan, a centaur, a comet, a small Solar System body, a Kuiper Belt object or a trans-Neptunian object.
The IAU prefer the term small Solar System body for comets and anything too small to use gravity to maintain an ellipsoidal shape, and have done so since their General Assembly of 2006 (IAU 2006), the same one that decided the fate of Pluto. According to this classification, anything that is not a planet, but which is able to become roughly planet-shaped is a dwarf planet.
So now we have to briefly ask “What is a planet?” well, according to Resolution 5A of IAU 2006 a planet has to (a) be orbiting the Sun, (b) be able to use its own gravity to keep a nearly round shape, and (c) be sufficiently well-developed to have “cleared the neighbourhood“. This might be a new phrase to you, but all it means is that the object under consideration has become the dominant one in its orbit, so that there is nothing left nearby of comparable size (except possibly its own satellites). A dwarf planet meets conditions (a) and (b), but not (c).
So, let’s have a quick look at a couple of the various types of non-planets (I don’t want to drive you away by tackling them all at once).
There are presently known to be five DWARF PLANETSin the Solar System. These are Pluto, Ceres, Eris, Haumea and Makemake. Several further trans-Neptunian objects (including Sedna and Quaoar) may well swell their ranks shortly, but their size and distance makes pinning them down difficult. However, as the outer reaches of the Solar System are explored it is thought that hundreds, possibly thousands, more will turn up. It is probably only our inability to see beyond the Kuiper Belt that is keeping the numbers down.
I’m not fond of the term dwarf planet, as it suggests that these are small planets, whereas the idea was, I believe, that they aren’t planets at all. For this reason I would maybe prefer the older term planetoid. The Japanese have got the right idea: their name for dwarf planets, junwakusei, can be translated as “almost a planet”, which I like almost as much as the suggestion of Alan Stern and Harold Levison from their paper to the IAU in 2000. They adopted the words überplanet for the big eight, and unterplanet for the rest. TROJANS are interesting characters. I don’t want to get bogged down explaining Lagrangian points and barycentres (yet) so I’ll just say that a trojan shares an orbit with another (larger) body at the Lagrangian points, approximately 60° ahead of or behind it. We have more interchangeable terminology here: a trojan can also be called a Lagrangian object, and the Lagrangian points are sometimes called trojan points. Saturn has a great collection of trojan moons: they are (i) Telesto and Calypso (trojans of Tethys), and (ii) Helene and Polydeuces(trojans of Dione).
Jupiter also has a large collection of trojans, traditionally named after the two camps of the Trojan Wars. Greek trojans are located at one Lagrangian point, and Trojan trojans are at the other. There are two exceptions to this rule (because their discovery pre-dates it): they are 617 Patroclus ( a Greek, but with the Trojans), and 624 Hektor (a Trojan with the Greeks). I never liked Hektor much when I read the Iliad, so this doesn’t surprise me in the slightest.
Next time I get a quiet day I’ll move onto centaurs and Kuiper Belt objects (if I remember).
I feel sorry for Pluto. When I was younger it was the ninth biggest planet in the solar system, but unfortunately is now (probably) only the second biggest “dwarf planet” following the discovery of minor-planet 136199 Eris by the Palomar Observatory on January 5th 2005. This discovery encouraged an acceleration of the debate over whether or not Pluto should ever have been called a planet, the result being that the IAU published their Definition of a Planet in the Solar System on August 24th 2006. So I suppose that’s the day on which Pluto stopped being a planet, and became a Kuiper Belt Object. And as if that weren’t damage enough for Pluto’s image, there is still a debate going on as to whether Pluto and Charon should be re-classified as a binary system. At the moment Charon is a moon of Pluto; but the centre of their combined mass doesn’t lie within either body, so strictly speaking it should get higher billing.
On the upside, Pluto does get its own Disney character, and lends its name to both plutoids (anything beyond the orbit of Neptune that has managed to attain a roughly spherical shape) and plutinos (anything in the above group that orbits the Sun twice in the same time it takes Neptune to make it round three times).
Pluto was discovered on February 18th 1930 by Clyde Tombaugh from Illinois. Tombaugh was a prolific discoverer of variable stars, and also of asteroids, many of which he found while searching for Pluto. But Pluto will always be his claim to fame, and following his death in 1997 a small quantity of his ashes were sent on their way out there aboard the New Horizons probe, which arrived at the ex-planet on July 14th 2015 to a blaze of publicity, and began sending back fabulous snapshots.
And not before time, as you can see from the second photograph (below); because close-ups of Pluto from the enormous distance of the Earth don’t reveal a great deal of detail.
As well as the aforementioned Charon, Pluto has four other moons: Nix, Hydra, Kerberos and Styx. All moons of Pluto are named in accordance with the convention that they are mythological, and have some association with their parent (Hydra, for example, was the nine-headed guardian of an entrance to the underworld).
As I just mentioned, Pluto is a Kuiper Belt object (KBO). The Kuiper belt, (rhymes with sniper, not kipper, although I have to admit that I do find the concept of a kipper belt rather appealing) or, to give it its full name the Edgeworth-Kuiper Belt, stretches from about 30 to 50 AU from the Sun, and contains an enormous number of mostly smallish bodies (trans-Neptunian Objects, or TNOs) left over from the formation of the Solar System.
Why Edgeworth gets edged out in popular literature while Kuiper gets the kudos is something I might know more about by the time his birthday comes around (Feb 26th, 1880). Neither of them correctly predicted what the belt was like anyway, so it’s anybody’s guess.
Anyhoo, there are thought to be as many as 100,000 TNOs within the belt with a diameter of over 100km (which is why I say “smallish” not “small”) and, because Pluto is now a member, everybody knows the name of at least one.
Results from New Horizons are changing our view of Pluto for ever. It now see that a crust of water ice might be acting in place of a bedrock, supporting mountains made of frozen nitrogen and methane. It also seems that Pluto might, somehow, be still geologically active. We need to visit again!
February 18th, 1977 was the day on which the space shuttle Enterprise made her first “attached” flight. Strictly speaking, I suppose, this wasn’t the maiden flight of a shuttle, as Enterprise was securely strapped to the back of a specially adapted Boeing 747 for the duration. I now know that she didn’t have any engines or a heat shield, and was therefore incapable of actually flying in space, but at the time I was young(er), and mightily impressed (and it was the first time a shuttle’s wheels had been higher than the hangar roof, so it counts). I was even more impressed when Enterprise was flown, again attached to the 747, over the family home at Brown Edge, Staffordshire, six years later as part of a promotional tour of Europe, drumming up satellite launching business for NASA.
Asteroid 624 Hektor was discovered on February 10th 1907 by August Kopff, a German astronomer working out of the Humboldt University of Berlin, who eventually discovered 68 asteroids.
Being numbered 624 would normally put it below the radar, but this one gets a mention because it is the largest of the Jupiter trojans. It’s a reddish D-type asteroid (as are the majority of Jupiter trojans) and lies at the L4 Lagrangian point (in other words it precedes Jupiter in its orbit).
L4 Jupiter trojans are supposed to be named after characters from the Greek side of the Trojan Wars. Hektor is therefore misnamed, as he was on the Trojan side (617 Patroclus is also in a similar predicament, being a Greek hero in the Trojan camp at the L5 Lagrangian point).
Hektor measures 370 km long by 200 km wide, an unusual shape for an asteroid, leading astronomers to conclude that it might be a “binary”, two conventionally shaped asteroids drawn together by their mutual gravitational pull. Observations indicate this may well be the case, but with an object of that size at such a great distance, it’s hard to be absolutely sure.
Hektor has also been shown to have a moon, about 12 km in diameter, going by the name S/2006 (624) 1. Around 6,000 Jupiter trojans are known at present (although there are thought to be around a million up there of over 1 km diameter). At present, Hektor is the only one at L4 thought to be a binary, and the only one known to have a satellite.
Hektor (you can call him Hector if you like, but there is no “C” in the Greek alphabet), as you may know, was the son of King Priam and Queen Hekabe, and the greatest Trojan hero of the wars, making it all the more unusual that he should be named as one of the Greek asteroids.
Asteroid 212 Medeawas discovered from Pula (or Pola) in Croatia by Johann Palisa on February 6th 1880. It’s another big main-belter, about 144 km (90 miles) across, with, in the absence of much else to say about it, the following orbital characteristics, plucked from the JPL Small Body Database:
27 April 2019
Average Orbital Speed
Longitude of Ascending Node
Argument of Perihelion
Medea is our second Greek tragedy in two days. This one is by Euripides (c. 484 to 406 BC), the most modern of the “big three” Athenian dramatists. He was about fifty when he wrote it, and it was perhaps a little too much for his audience, who placed it last in the City Dionysia of 431 BC, behind Sophocles in second, and Euphorion (son of the more famous Aeschylus) who won.
Medea was the wife of Jason (of “and the Argonauts” fame). She obviously had a sharp temper, shown most vividly by her killing her own children to spite Jason after he’d had a fling with the daughter of the King of Corinth.
Asteroid 129 Antigone was discovered on February 5th, 1873 by C H F Peters. It’s a fairly regularly shaped body of about 120 km across, and is composed of a nickel-iron mix, putting it firmly in the metallic M class, and leading scientific types to conclude that it is probably the remains of the core of a planetesimal, destroyed at some point in the dim and distant past.
Antigone, as you know, was the daughter of Oedipus, the king of Thebes, and Jocasta, his queen (and mother). Basically, after Oedipus’ death, Antigone upsets King Creon, Oedipus’ predecessor, who had taken the opportunity to rule Thebes again after Oedipus’ sons had fallen out with one another in a big way. The upset comes about as a result of Antigone trying to arrange a decent burial for her brother Polynices, who was regarded as a traitor. Long story short: she hangs herself, and her beau (Creon’s son Hæmon) kills himself in his grief.
The depiction of Oedipus and Antigone above is by the amazingly-named Aleksander Kokular (1793 – 1846) a Polish painter and educator, and co-founder of the Warsaw School of Fine Arts. He was well-known for his mythological (as you can see) and religious works.
The story of Antigone with which most of us are familiar comes from Sophocles’ three Theban Plays (there are three of them, but they’re not a trilogy). I can`t recommend the Theban Plays highly enough. I consider Sophocles to be way above Aeschylus and Euripides when it comes to tales of misery and woe. Euripides did actually write an Antigone himself; the text is lost, but it’s known that tragedy is averted in this version by divine intervention. That’s not what I want! It’s supposed to be a tragedy! Make it tragic!
And I’m going to get really nerdy now, and say try to get the E F Watling translation. Robert Fagles is fine, but Watling is my preference.
Today’s second photograph is the front cover of my latest copy of the Theban Plays (Penguin Classics). It shows Oedipus dressed as a traveller (in other words wearing a hat and carrying a staff) pondering the riddle of the Sphinx.
1877 – S-type asteroid 172 Baucis discovered by Alphonse Borrelly, and named after a character in Ovid’s Metamorphoses.
1987 – Japanese X-Ray satellite Ginga (otherwise known as Astro-C) was launched. It sounds like an acronym, but it isn’t. It’s Japanese for “galaxy”.
2002 – The Reuvan Ramaty High Energy Solar Spectroscopic Imager (HESSI, or RHESSI) was launched to study solar flares, with a view to working out why they occur, and how so much energy can be released in such a short time. Reuvan Ramaty, by the way, was an expert in cosmic rays, and one of the original members of the HESSI team. Unfortunately he died on April 8th, 2001, less than a year before launch.