April 29 – 68 Leto

Asteroid 68 Leto was discovered by Robert Luther on April 29th 1861.  It’s a fairly big main belt asteroid (about 125km diameter) with an absolute magnitude of 6.78, and an apparent magnitude from down here of 9.56 when at its brightest.

Leto was the daughter of the Titans Coeus and Phoebe, and mother (by Zeus, of course) of Apollo and Artemis.  She was thought to have been born on the island of Kos.  Apart from her role in bearing two important gods, Leto is hardly heard about in Greek writing and seems to have been content to remain in the Olympian background.  This fits in with her being generally portrayed as a demure woman, modestly lifting her veil.  The word letho means “to move unseen”, which may explain it.  Perhaps she’s hiding from Hera, Zeus’ wife.

Latona and the Lycian Peasants, by Jan Brueghel the Elder (about 1605).

Latona and the Lycian Peasants, by Jan Brueghel the Elder (about 1605).

The oil painting above, by Jan Brueghel the Elder, shows another incident from Leto’s life, also concerning Hera.  In a foul mood at discovering that Leto was to bear children to Zeus, Hera cursed her to be shunned everywhere she went.  In the painting, she is attempting to drink from a pond in Lycia (southern Turkey), but is being prevented from so doing by the locals, who are stirring up the mud from the bottom of the pond.  She responded by turning them into frogs.


Also today, it now transpires that in 1801 main belt asteroid 69 Hesperia was discovered by Italian astronomer Giovanni Schiaparelli from Milan.  Previously the discovery date had been thought to be April 26, but in an editorial notice of August 29th 2015 the Minor Planet Center announced that an examination of the literature of the time of the discovery shows that the date should in fact be pushed back three days.

Being a patriotic kinda guy, Schiaparelli had named his new discovery in honour of his home country, but for some reason used the Greek name for Italy rather than the Latin (or Italian) one.  The M-type Hesperia is a fairly chunky size, and would be about 130 km in diameter, if it were a sphere (which it isn’t).  I use the word “diameter” a lot in this blog to describe asteroids, but it just means “wide in no particular direction”.

April 28 – Oorter Space

We have two birthdays today.

Johann Oskar Backlund was born on April 28th 1846 in Länghem, Sweden, but after university spent his career in firstly Tartu, Estonia (part of Imperial Russia at the time) and then Pulkovi (also Russia). He was a dab hand at celestial mechanics, and became so well known in Russian astronomical circles for his work on comet 2P/Encke that Russian sources sometimes refer to it as Encke-Backlund.

Oskar Backlund

Oskar Backlund

 

2P/Encke is believed to be the source of the Taurid meteor shower, but Backlund was more interested in the effect it might be having on Mercury, and used the perturbations produced by the motion of the comet to predict the mass of the planet. If I had a copy of the 1961 journal Soviet Physics I might be able to share his results with you (unless they were in Russian, which seems likely).


Jan Oort was also born on this day, in 1900, in Franaker, Friesland (the Netherlands). He was mostly drawn to radio astronomy, and his day job was as a professor at the University of Lieden, under Director Ejnar Hertzsprung. Among Oort’s many career highlights were the discovery of a group of stars outside the Milky Way (the galactic halo), the calculation of how far away and in what direction lies the centre of the galaxy, and of course the idea that comets originate in what is now commonly known as the Oort Cloud, a roughly spherical region of icy planetesimals surrounding the Sun at distances of up to an almost unbelievable 50,000 AU (defining the limits of our home star’s gravitational supremacy).

Jan Oort (image: Nationaal Archief NL Fotocollectie Anefo)

Jan Oort (image: Nationaal Archief NL Fotocollectie Anefo)


1903  –  Discovery of asteroid 509 Iolanda (a.k.a. 190LR) by Max Wolf. Iolanda is an S-type main belt asteroid, and the NASA JPL Small-Body Database Browser gives it a diameter of just under 53km, an absolute magnitude of 8.40, and a rotation period (day) of 12.306 hours.


1928  –  Birth of Eugene Shoemaker, a leading light in the development of astrogeology, but mostly remembered these days as co-discoverer of comet Shoemaker-Levy 9, which famously collided with Jupiter in 1994.


1999  –  Launch of the ABRIXAS X-Ray Telescope by the German Deutsches Zentrum für Luft und Raumfahrt from the Kapustin Yar facility in Russia. The mission lasted approximately three days, thanks to an accident involving an overcharged battery.


2003  –  Galaxy Evolution Explorer (GALEX) launched.


April 27 – Apollo 16 Returns Home

We have two spaceflight-related events today. The first is the splashdown of Apollo 16, about which I have written elsewhere. I’m mentioning it mainly to get this brilliant photograph in.

Apollo 16 Arrives (image: NASA)

Apollo 16 Arrives (image: NASA)


The second is from the other side of the iron curtain . . .

We have a birthday boy today, and it’s the man who has spent more time away from Earth on a single trip than anyone else in history. From 1994 to 1995 Valeri Vladimirovich Polyakov stayed aboard the Mir space station continuously for 437 days, completing over 7,000 orbits of the Earth.

Polyakov (born Korshunov – he changed his name when he was adopted by his stepfather) was born in Tula, Russia, on April 27th 1942, and studied at the I M Sechenov Medical Institute in Moscow, specialising in space medicine. This helped get him selected as a cosmonaut in 1972, although he didn’t get his first flight until 1988, a brief (by his standards) 240 days.

The main event, in 1994, also gave him the record for the longest total time spent in space, though this has since been broken. The purpose of such a long stint was to see how astronauts would react physically and mentally to a long-duration flight to Mars, and whether they would be capable of doing any decent work when they arrived. The results were promising, with no evidence of long-term performance problems following his return to Earth.

Polyakov retired from cosmonauting in 1995, and became deputy director of the Ministry of Public Health in Moscow.


 

April 26 – Asteroid 83 Beatrix

1859  –  Birth of Italian astronomer Vincenzo Cerulli, one of the first people to suggest that Martian canals might be an optical illusion.  Cerulli discovered one asteroid, 704 Interamnia, named in honour of his home town.  Wikipedia has his birthday as April 20th, but other sources seem to agree on the 26th.


1865  –  Asteroid 83 Beatrix discovered by Annibale de Gasparis, another Italian.  It is an X-type asteroid, signifying it is part of a group of bodies with similar spectral characteristics, but not necesarily similar compositions.  This one was named for Beatrice Portinari, popularly thought to be the inspiration for the guide Beatrice in Dante’s Divine Comedy.

"Dante and Beatrice" b y Henry Holiday. (Beatrice is second from the left.)

“Dante and Beatrice” b y Henry Holiday. (Beatrice is second from the left.)


1876  –  Asteroid 163 Erigone discovered by Henri Joseph Anastase Perrotin, director of the Nice Observatory, and discoverer of six asteroids.  A rare opportunity was missed last year when Erigone occulted the first magnitude star Regulus.  This kind of happening is rarely seen from heavily populated areas, and this one would have been visible from a small track that included New York.  Unfortunately Spode’s Law came into effect and it rained heavily throughout the quarter of an hour of the event.


1884  –  Main belt asteroid 236 Honoria discovered.  Honoria is named after the sister of Emperor Valentinian III.  She gets into the history books mostly as the perpetrator of one of the worst decisions ever made: asking Attila the Hun to help her get out of a dull marriage.  Honoria was discovered by Johann Palisa.  it is about 86 km across, and is a stony S-type.


1933  –  Birth of Arno Penzias, co-discoverer with Robert Wilson of the cosmic microwave background radiation, the faint echos of the Big Bang.


1957  –  Transmission of the first episode of “The Sky At Night” by the BBC.  Under the legendary Sir Patrick Moore, it became the longest running television programme in the World to have one presenter.


1962  –  Launch of Ariel 1 (UK 1) the first British satellite.  Surprisingly, given our lackluster approach to spaceflight today, this launch made the United Kingdom the third country on the planet to have their own satellite (but we needed the Americans to launch it for us from Cape Canaveral).


April 25 – Gérard de Vaucouleurs

Born today in 1918, Gérard de Vaucouleurs was a French astronomer who specialized in galaxies.   He is best known these days for his modification of Edwin Hubble‘s galaxy classification scheme.  De Vaucouleurs added barsrings and spiral arms to Hubble’s basic system of ellipticalspiral and lenticular galaxies.

Barred Spiral Galaxy NGC 1300 (image credit: NASA/ESA).

Barred Spiral Galaxy NGC 1300 (image credit: STScI/NASA/ESA).

In honour of Monsieur de Vaucouleurs, Today’s photo (a composite image by the Hubble Space Telescope) shows the most barred, armed, spiral galaxy I could find.  NGC 1300 is in the constellation Eridanus. It was discovered by John Herschel in 1835, and is a member of the Eridanus Cluster of about 200 galaxies.


 1848  –  The large main belt asteroid 9 Metis was discovered by Irish astronomer Andrew Graham.  It was to be the last Irish asteroid for 106 years.


1890  –  Asteroid 291 Alice, of the Flora family, discovered by Johann Palisa. Alice is roughly the shape of a giant jelly bean, at about 19 x 12 x 11 km.


1890  –  Asteroid 292 Ludovica was also discovered today, and was also one of Johann Palisa’s. Palisa was obviously smoking on April 25th, whereas Auguste Charlois was probably steaming some time afterwards, as he too discovered both asteroids, but on the 26th.


1906  –  Asteroid 599 Luisa was discovered from Taunton, Mass., by prolific American asteroid and comet hunter Joel Hastings Metcalf. The origin of the name isn’t known, but I would like to point out that Metcalf’s father was called Lewis.


1993  –  Launch of X-ray telescope Alexis (Array of Low Energy X-Ray Imaging Sensors).


April 23 – AGILE

AGILE (Astro‐rivelatore Gamma a Immagini Leggero) was launched April on 23rd, 2007.  AGILE is an Italian satellite, and is armed with x- and gamma ray imagers, a calorimeter (basically a device for measuring heat), and an anticoincidence system (a means whereby unwanted background events that would interfere with the results of the other detectors are suppressed, and it’s all getting a bit complicated, so I’ll stop there).


Also today, asteroid 1225 Ariane was discovered in 1930 by the Dutch astronomer Hendrik van Gent.  This is the first mention of Dr van Gent in these pages.  He discovered quite a few asteroids, but his contribution to astronomy was cut short by his sudden and untimely death at the age of 47.

Ariane

The name relates to a character in Gabriel Marcel’s exploration of good and evil, Le Chemin de Crête.


April 22 – PSR B1257 12A

Extra-solar planet PSR B1257+12A was discovered on April 22nd 1994 by Aleksander Wolszczan and Maciej Konacki.

As exoplanets go it’s quite small.  Somehow it has been determined that this 500 parsec distant object that nobody can see is just twice the size of the Moon.  Only Kepler-37b (slightly better name) is smaller, while at the same time still managing to retain the description “planet”.  If it were much smaller it would probably not be called a planet.  The “PSR” in the same lets you know that this planet is orbiting a pulsar, a rotating neutron star, formed during the collapse of a massive star during a supernova.  This particular pulsar has a rotation period measured at a staggering 6.22 milliseconds, which, for the older readers among you, is 123 times faster than a 78rpm record player.

Three planets have so far been discovered around pulsar PSR 1257+12 by the Arecibo telescope in Puerto Rico.  All three have tight orbits, and would fit within the orbit of Mercury.  They were the first extra-solar planets to be discovered, with “B” and “C” being found first, followed by a third which, because it was closer to the star, became “A”.

April 21 – 137 Meliboea and 162 Laurentia

Asteroid 137 Meliboea was discovered by Johann Palisa on April 21st 1874.  It is the largest of a family of similar asteroids, which includes the wonderfully named 2829 Bobhope, discovered by E L Johnson in 1948 and named after the legendary comedian.

Meliboea is a C-type asteroid of about 145 km (90 miles) wide, with an absolute magnitude of 8.1.  There are several Maliboea’s in Greek mythology, and it isn’t known after which one this particular discovery was named.


Two years later, on April 21st 1876, French astronomer brothers Paul and Prosper Henry spotted their ninth asteroid, 162 Laurentia, with credit for the discovery being attributed to Prosper, in line with their habit of taking one each alternately.  The name they chose was a tribute to another French astronomer, A. Laurent, discoverer of asteroid 51 Nemausa in 1858.  Laurentia is another C type, with a diameter of approximately 99 km (61 miles).


Our third and final asteroid of the day is 470 Kilia, discovered by Italian astronomer Luigi Carnera on this day in 1901.  Kilia is fairly small, at 26 km across (16 miles), and according to the JPL Small-Body Database, it is a stony “S-type”, and has been named in honour of the German town of Kiel, on the Jutland peninsula.

Luigi Carnera

Luigi Carnera

Carnera was always going to find an asteroid or two, as he had worked for Max Wolf, German asteroid-bagger extraordinaire.


1972  –  At 02:23 UT, John Young and Charles Duke, in the lunar module of Apollo 16, touched down on the Moon.  Pilot Ken Mattingly II had to stay behind to ensure the command module didn’t escape while they were down there.


April 20 – 532 Herculina

Asteroid 532 Herculina was discovered this very day in 1904 by Max Wolf, born 21/06/1867 in Heidelberg, studied at Heidelberg, Chair of Astronomy at Heidelberg, died 03/10/1932…  Can you guess where?

Wolf discovered a phenomenal 248 asteroids, presumably in the time he saved by not bothering to leave Heidelberg.  Herculina was his 9th of 1904, a year in which he was finding the critters at about one every three weeks.

Heidelberg Resident, Max Wolf.

Heidelberg Resident, Max Wolf.

With a diameter of 225 km, Herculina is one of the larger main belt asteroids, probably in the top 20.  It has a nicely elliptical orbit which takes it from 2.3 to 3.26 AU from the Sun.

For a while Herculina was suspected to have a “moon”, following observations made in the 1970′s, but further studies have failed to find it.  And that’s also pretty much the story of my attempt to find the location from whence was plucked the name.  Herculina doesn’t appear to be anyone or anywhere in particular.  Wolf’s previous asteroid, 531 Zerlina, is a character from Don Giovanni, and his next one, 539 Pamina, is from The Magic Flute.  But Herculina is a mystery.


1903  –  Discovery of asteroid 508 Princetonia.


April 19 – 161 Athor (and friends)

There’s a lot going on today, and I couldn’t decide which to concentrate on, so here they all are, chronologically, in brief, beginning with . . .

1855  –  C-type main belt asteroid 35 Leukothea (a Greek sea goddess) discovered by Robert Luther.


1870  –  86 km wide M-type main belt asteroid 110 Lydia (a country in Asia Minor in the 15th and 14th centuries BC) discovered by Alphonse Borrelly.


1876  –  M-type main belt asteroid 161 Athor discovered by James Craig Watson.  Hathor, after whom this asteroid is named, was an Egyptian goddess of fertility, motherhood, beauty, and (unusually) mining.  If she looks a little odd in the picture it’s because she is often depicted as a cow.

Hathor emerging from a bed of papyrus

Hathor emerging from a bed of papyrus


1879  –  Carbonaceous asteroid 195 Eurykleia discovered by Johann Palisa.


1882  –  Asteroid 225 Henrietta discovered by Johann Palisa, and named after the wife of French astronomer Jules Janssen.


1955  –  Death of Albert Einsteinamateur violinist (among other things).  There are many witticisms attributed to Einstein, and I was tempted to put one in, probably the one concerning pretty girls and stoves, or the definition if insanity.  But trying to find a definitive translation from German, or even proving that the great man ever said them, is harder than I thought.


1971  –  Launch of Orion 1 space observatory, loaded aboard Salyut 1, the first ever space station.


1975  –  Launch of ARYABHATA, India’s first satellite (launched on their behalf by the Soviet Union).