A brace of early asteroids were discovered on October 31st. First today we have 261 Prymno, spotted by C H F Peters in 1886. Prymno is in the main belt, is about 51 km wide, and is a relatively uncommon B-type. These are similar to C-types, but are generally lighter in colour than their carbonaceous cousins, and tend to have a bluer spectrum. Asteroid 101955 Bennu is another B-type, about which I expect to be saying a lot more following the conclusion of the OSIRIS-REx mission.
Prymno is named after an Oceanid of Greek mythology. They were the daughters (numbering an impressive 3000) of the God Oceanus, the personification of the sea. Oceanus also had 3000 sons (of course) who were river gods known as the Potamoi.
Our second asteroid today is 281 Lucretia, discovered two years after Prymno by Johann Palisa. A fairly small S-type asteroid of about 12 km diameter, Lucretia is a member of the Flora family of asteroids, a big group (about 5% of main belt asteroids are in this family) located in the inner main belt.
The naming of Lucretia has nothing to do with the Borgias, and everything to do with the middle name of German-born astronomer Caroline Herschel, sister of the more famous Sir William Herschel.
There isn’t a great deal to say about 280 Philia, discovered on this day in 1888 by Johann Palissa at Vienna Observatory, except that it is in the main belt, is about 46km in diameter, has an absolute magnitude of 10.7, and takes 1,845 days to orbit the Sun at a little over 17.3km/second.
Philia is usually translated into English as “brotherly love” (as in Philadelphia), but Aristotle, in his Nicomachean Ethics, gave it the broader meaning of friendship, which he then sub-divided into three distinct types, according to why they were formed. These are (i) “friendships of utility”, which we would probably call acquaintances; (ii) “friendships of pleasure”, such as those formed by people who meet through a common hobby, and (iii) “friendships of the good”, the highest level of friendship, formed by those who enjoy each other simply for who they are.
The Greek muse of sacred music was chosen to be the namesake of French astronomer Jean Chacornac’s second asteroid, 33 Polyhymnia, discovered on October 28, 1854.
Approximately 62km in diameter at its widest point, and rotating once every eighteen hours, this S-type main belt minor planet has an absolute magnitude of 8.55, and an unusually high eccentricity for such an early discovery, which helps it to reach quite good apparent magnitudes at certain times (10th magnitude is not unknown when Polyhymnia is close to Earth).
The muse Polyhymnia is often depicted as rather a serious figure, in a thoughtful or contemplative pose (holding her finger to her mouth, for example). Now, this is all very well for the muse of sacred hymns, but as she is also responsible for pantomime, I’m not sure I can take her all that seriously.
1971 ⇒ Launch of the Prospero satellite (X-3) by the UK, using a British Black Arrow rocket, making it the first all-British launch (almost – the launch took place from Woomera, South Australia). The UK’s previous satellite was called Ariel, so you’ll probably not need telling which Elizabethan playwright is being nodded toward in the choice of names. Prospero is still up there, and isn’t expected to decay until 2070.
Although no longer a working satellite, Prospero was contacted every few years, usually on the anniversary of its launch (but not recently).
And now it’s time for another of those rare events, a British satellite launch. This one was in 2005.
TopSat(Tactical Operational Satellite) is a small satellite, only about 80cm across, designed to show that size isn’t necessarily important when it comes to satellites. It carries an ingeneously designed camera capable of much higher resolution images than would normally be possible from anything that can be held in such a small area (they do it with mirrors).
TopSat was conceived, designed and built in Britain by a consortium of companies. Such a shame they had to launch it from Russia, on a Russian rocket. The launch was one way in which costs were kept down. TopSat was one of a flock of nine satellites launched by the same vehicle.
I have no idea whether TopSat is still in a usable state. The latest news I could find on the mission dates from 2012, and refers to the satellite being “in hibernation”.
Kosmos 186 was launched on this day in 1967 by the Soviet Union. It was followed three days later by the identical Kosmos 188, and together they performed the first ever fully automated docking by two spacecraft. Both were unmanned, which was probably wise at a time when space authorities on both sides of the iron curtain were recovering from tragedies, following the deaths of the three-man crew of Apollo 1 from the USA, and Vladimir Komarov (Soyuz 1) of the USSR.
For the younger readers among you, DDR stands for Deutsche Demokratische Republik (the old East Germany).
You might have expected the second of this pair to have been called Kosmos 187, but such was the frenzy of launches happening at the time, accelerated by the requirements of Cold War governments, that there had already been another Kosmos sent up in the three days between Kosmos 186 and 188.
Main belt asteroid 32 Pomonawas discovered on October 26, 1854, by Hermann Goldschmidt. It is a stony “S-type” asteroid of, according to IRAS observations, just under 81 km wide. Travelling at around 18 km per second, Pomona orbits the Sun once every 1,520 days.
Pomona has been shown to rotate once every 9.4 hours. This figure is arrived at by measuring the asteroid’s light curve, a collection of measurements of an astronomical object’s brightness over time. Because the average asteroid is not a perfect sphere with a uniform colour, if you have a sensitive enough receiver (because the magnitude differences are likely to be very slight) you can build up a series of brightness measurements that will vary, hopefully in a regular way, depending on which part of the asteroid is facing you. Plotted on a graph these will form a repeating pattern, and the gap between similar peaks or troughs will give you the time taken for the same part of the body to be facing in your direction.
If the name Pomona reminds you of apples, that’s not a coincidence, as she was the Roman goddess of fruits and orchards. From her Latin root (pommum) the French get their pomme, and the rest of us get pommade, which was originally perfumed with apples.
Iapetus, the third largest moon of Saturn, was discovered on October 25th, 1671, by Giovanni Cassini, and is a weird old place for a couple of reasons. Firstly, it looks like two different moons, depending on whether you view it from the leading or trailing hemisphere, and secondly because of a pronounced ridge around the equator that gives the moon the appearance of a walnut.
The colour difference is really obvious. It was first suggested by Cassini himself, who noticed that he could only see Iapetus when it was on Saturn’s western side. Various theories have been put forward to explain this two-tone look, with the latest being to invoke thermal segregation , as a result of Iapetus’ very long rotation period (79 Earth days). This might cause one side to be brighter than the other, with Iapetus’ tidally locked rotation being the reason it will always look darker from Earth when on one side of the planet.
The equatorial ridge has proved equally baffling, with two formation theories currently being pondered: (i) the result of much faster rotation at some point in the past, and (ii) the collapse of a ring.
Iapetus was named after one of the Titans of Greek mythology, as per John Herschel’s suggestion that they be given the names of the mythological siblings of Kronos (the Greek equivalent of Saturn). Iapetus is sometimes credited with being a distant ancestor of the human race, and the story goes that each of his four sons (Atlas, Prometheus, Epimetheus and Menoetius) was responsible for a particular fault in mankind. Thanks, Iapetus.
We have a double-header today. Two moons of Uranus, Ariel and Umbriel, were discovered on October 24th 1851 by Bolton-born William Lassell, brewer and keen amateur astronomer, who was in the fortunate position of being able to use his not inconsiderable wealth to fund the construction of impressive telescopes.
Let’s take a quick look at Ariel first, a reasonably large moon of just over 579 km radius, orbiting its parent at a distance of about 190,000 km. It travels at a fantastic pace, completing an orbit of the vast planet below it in two and a half Earth days.
Of all the moons of Uranus, the surface of Ariel appears to be the youngest, evidenced by the lack of older, larger impact craters, and the presence of recent geologic activity. It is also the brightest of the large Uranian moons, and is tidally locked (keeps the same face to the planet at all times). Ariel has only been visited up close and personal by one mission, Voyager 2, and as far as I know there are no plans to make a return journey just yet.
If you’ discover a moon of Uranus you have two choices from which to choose a suitable name: Alexander Pope’s The Rape of the Lock, or the plays of William Shakespeare. At the sugestion of Lassell, Ariel was chosen by Sir John Herschel, son of Sir William Herschel, the discoverer of Uranus. It’s a good choice, as it falls into both categories.
Now we move outwards slightly to Umbriel, which gets its name from that of a sprite in Pope’s narrative poem. It too was chosen by John Herschel.
Umbriel is the third farthest major moon from Uranus (Ariel is the second), and is the darkest of the major Uranian satellites. We don’t yet know why Umbriel is so much darker than similarly sized bodies in orbit around Uranus, but I’m sure somebody’s working on it somewhere. With a radius of 584 km, it is only slightly larger than Ariel, and, like it’s neighbour, it’s no slouch, travelling at the impressive rate of 16,800 km/hour, meaning a year on Umbriel takes about four and a half Earth days.
For, that sad moment, when the Sylphs withdrew And Ariel weeping from Belinda flew, Umbriel, a dusky, melancholy sprite, As ever sully’d the fair face of light, Down to the central earth, his proper scene, Repair’d to search the gloomy Cave of Spleen.
(The Rape of the Lock, Alexander Pope, 1714)
1601 – Death of the Danish astronomer, Tycho Brahe, whose use of the title De Nova Stella to announce the supernova of 1572 led to the word nova being applied to all such phenomena.
1890 – First meeting of the British Astronomical Association at the Hall of the Society of Arts in London. Unlike the already established Royal Astronomical Society, the BAA was open to female members, and even allowed them onto its council. One can only speculate of course, but I assume the RAS had somehow decided that night vision was improved by ownership of testicles.
1964 – Launch of Kosmos 49 (DS-MG 2) to test orientation systems and study the magnetosphere. The launch was from the Kapustin Yar site near Volgograd (previously known as Stalingrad). The mission was a short one, and the satellite’s orbit decayed on August21st the year after launch.
2004 – Discovery of Saturn’s extremely tiny moon, Polydeucesby the Cassini Imaging Science team.
Asteroid 209 Dido, discovered by C H F Peters on October 22nd 1879, is a large, C-type main belt asteroid with a very low albedo. It is about 140 km (87 miles) in diameter, and completes one rotation every eight hours of its 2039 day journey around the Sun.
Dido was the mythological queen and founder of Carthage, and sister of Pygmalion (the guy who fell in love with a statue he had carved). She is best known for (i) her affair with Aeneas, the Trojan hero, and (ii) being the subject of an opera by Henry Purcell.
Today’s artistic offering is by Giovanni Francesco Barbieri (1591 – 1666), the self-taught, cross-eyed, fast painting Italian genius, more commonly known as Guercino (meaning “squinter”), responsible for more than 100 altarpieces and nearly 150 paintings.
1969 ⇒ Splashdown of Apollo VII, the first manned Apollo mission.
1905 ⇒ Birth of Karl Jansky, one of the founding fathers of radio astronomy.
Today we say hello to 76 Freia, a large, dark, main belt asteroid, discovered on this day in 1862 by an extremely occasional visitor to these pages, the German astronomer Heinrich d’Arrest (this is his only asteroid discovery). Freia is a member of the Cybele group of asteroids, in the outer reaches of the main belt. They are thought to be the remnants of a large object which broke up some time long ago.
The goddess Freyja, after whom you have probably deduced this asteroid is named, is a typically strange member of the Norse deities. She drove a chariot drawn by cats, and was seldom seen in public without her sidekick, a boar called Hildisvini, which she would also ride when her pussy wagon wasn’t available.
Freyja, possibly meaning “lady” (as in the German frau) is goddess of love, sexuality and fertility, and it is thought by some that she and Frigg (whom we may well meet on November 12 under the guise of the splendidly-named asteroid 77 Frigga) derive from a common Germanic predecessor.
Asteroid Freia’s vital statistics include a diameter of approximately 184 km, a rotation period (to all intents and purposes, a “day”) lasting a little under 10 hours, and a year equivalent to just over 6 of Earth’s.
1879 ⇒ Asteroid 208 Lacrimosa discovered by Johann Palissa.