August 13 – Discovery of Neptune’s moon Laomedeia (2002)

A very small moon of Neptune, Laomedeia, was discovered today in 2002 by a very large group of astronomers (so I won’t be naming them) using the Cerro Tololo Inter-American Observatory (CTIO) 4-m telescope and the Canada-France-Hawaii 3.6-m telescope on Mauna Kea. Laomedeia orbits the planet Neptune every 8.7 Earth years, and is a relatively tiny 42km in diameter (Neptune is about 49,000 km across). In Greek mythology, Laomedeia was one of the fifty Nereids. She is described, rather vaguely, by Hesiod as the “leader of the folk”. Make of that what you will.

Nereids mourning Achilles
Nereids mourning Achilles

I can’t find a representation of Laomedeia anywhere, but the black-figure hydria, above, shows nine of the Nereids, so there’s about an eighteen percent chance she’s in there somewhere.

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Physicist Anders Jonas Ångström was born today in 1814 in Lödgö, in the province of Medelpad, Sweden. A keen believer in the use of spectroscopy, he was the first person to examine the spectrum of the aurora borealis. He now gives his name to the unit of measurement of the wavelength of light, denoted by the letter Å.

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ALSO TODAY . . . .
1847 – Discovery of asteroid 7 Iris by J R Hind (his first). Iris is a very large S-type main belt asteroid, over 200 km wide in some directions, named after the goddess of the rainbow.
1861 – Discovery of asteroid 71 Niobe by (Karl Theodor) Robert Luther. Niobe is 83 km in diameter, and an S-type asteroid. It takes it’s name from the daughter of Tantalus in Greek mythology, who made the mistake of boasting about her fourteen children to the goddess Leto (who only had two). Some accounts say one child survived.
2001 – Discovery of Uranus’ moon Ferdinand. As far as we know, this 6 km wide moon, named after the King of Naples in Shakespeare’s The Tempest, is the most distant from the planet.

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August 08 – Happy St Dominic’s Day!

Today is the feast day of St Dominic, the patron saint of astronomers.

St Dominic (Claudio Coello, c.1685)
St Dominic (Claudio Coello, c.1685)

Dominic de Guzmán was born in Spain in 1170, and became founder of the Dominican order, which today numbers a relatively robust 6,000 or so friars.  It is thought he may have been an early member of the Spanish Inquisition (I bet you weren’t expecting that) and is actually seen in a painting by Peter Beruguette presiding over an auto-da-fé (a public act of penance by condemned heretics, popular with the Inquisition).

St Dominic is also indirectly and tenuously linked to the formation of Everton FC, a football club with its origins in the nineteenth century sporting ambitions of the St Domingo Methodist Church, Liverpool.


The High Precision Parallax Collecting Satellite (HIPPARCOS) was launched today in 1989 by the European Space Agency, at the start of a successful four year career.  As well as being an only slightly tortured acronym, Hipparcos is a surprisingly accurate spelling of the Greek astronomer (but he’d be Turkish if he was born in the same town today) more commonly known as Hipparchus of Nicaea.  The homage is to his work on all kinds of trigonometric problems, including his insight into the precession of the equinoxes.  The greatest astronomer until Ptolemy, he is even suspected of devising a heliocentric (Sun at the centre) theory of the solar system, which he abandoned because it relied (correctly) on the orbits of the planets not being perfect circles.

The purpose of the Hipparcos mission was, very simply, to tell us where stars are, and where they are going relative to us.  Providing astronomers with a highly accurate frame of reference has allowed other, older astrometric measurements to be fine-tuned.  It has enabled us to calculate much better determinations for such things as the ages and masses of stars, and the rotation of the Galaxy.

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ALSO TODAY . . .

1991  –  Astronaut Jim Irwin (Apollo 15) died.

2001  –  Launch of the GENESIS spacecraft to collect a sample of the solar wind.

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July 27 – Birth of Sir George Airy (1801)

Today is the birthday of Sir George Biddell Airy, born in 1801 at Alnwick (I think you pronounce it ‘annick’, but don’t quote me) in Northumberland, England.  If you pay a visit, you’ll probably recognise Alnwick from its castle, which has starred in two Harry Potter films, Downton Abbey, Star Trek: the Next Generation and The Black Adder.

Airy shone as a student at Cambridge, probably to the annoyance of his fellows. Like Isaac Newton before him, Airy was a sizar, a class of student whose parents could not afford to pay the full fees, but who were allowed entry on the understanding that they paid their way by working as a servant at the university while studying.

A mere six years after entering Cambridge Airy was appointed Lucasian professor of mathematics, one of the most prestigious academic posts anywhere, held over the years by (among others) Charles Babbage, Paul Dirac,  Stephen Hawking, and the aforementioned fellow sizar Isaac Newton.

Airy made several important discoveries in his time, including a tiny inequality in the motions of Venus and Earth that led to an overhaul of Delambre‘s solar tables.  He also came up with a new figure for the mean density of the Earth.  This was achieved by measuring the change in gravity as one descends into the Earth by using changes in the swing rate of a pendulum at the top and bottom of a deep coal mine. It turns out that at just over 1000 feet down the pendulum ‘gains’ two and a quarter seconds a day. From this, Airy was somehow able to calculate a specific density of about 6.5. Today it is thought to be 5.5.

Today’s picture is the un-astronomical A Shell Forge, by war artist Anna Airy, George’s granddaughter.

A Shell Forge (Anna Airy).
A Shell Forge (Anna Airy).

1879  –  Discovery of C-type asteroid 200 Dynamene by C H F Peters.


July 22 – Birth of Friedrich Wilhelm Bessel (1784)

Today is the anniversary of the birth, in 1784 of Friedrich Wilhelm Bessel, the German astronomer who was the first to use parallax to find the distance to a star.  The star in question was 61 Cygni, which Bessel decided was 10.3 light years away (the current measurement is 11.4 ly).  One can only marvel at Bessel’s ability, in 1838, to measure the unbelievably small angles involved.  The feat was somewhere akin to measuring the differences in direction of the left and right edges of a Brussells sprout located about three miles away.

Portrait of Bessel by the Danish artist C A Jensen
Portrait of Bessel by the Danish artist C A Jensen

Asteroid 30 Urania was discovered on July 22nd 1854 by John Russell Hind.  It is a main belt S-type asteroid of about 100km diameter at its widest point.

Urania
Urania

Urania is the Greek muse of astronomy, a daughter of Zeus, and great-granddaughter of Uranus.  She is usually represented wearing a cloak embroidered with stars.  The allegorical representation above is by the French portrait painter Jean Louis Tocqué.


July 18 – Birth of John Glenn (1921)

Today marks the birth, in 1921, of John Herschel Glenn, Jr,  (died December 8th 2016), liver of quite a full life, of Scottish descent (I believe he also had relatives in Sheffield), and born in Cambridge, Ohio.  Reading that sentence back the word “liver” sounds a bit anatomical, but I’m going with it anyway.

Glenn was a member of Astronaut Group 1, more commonly known as the Mercury Seven, the original hand-picked, hard-boiled, right-stuff-infused group of astronauts selected by NASA in 1959, who had a presence in all of the classes of manned American spacecraft of the twentieth century (MercuryGeminiApollo and Shuttle).

John Herschel Glenn Jr, of the clan Glenn-Macintosh. (Image credit: NASA).
John Herschel Glenn Jr, of the clan Glenn-Macintosh. (Image credit: NASA).

Here’s a potted history of some of John Glenn’s achievements:  fighter pilot in the South Pacific, North China and Korea; test pilot; first supersonic transcontinental flight; first American to orbit the Earth; senator (Democrat); oldest person in space.

On a slightly less joyous, less happy-birthday-to-you-ous note, he managed to get himself caught up in the Lincoln Savings and Loan affair, and was for a time opposed to the inclusion of women in NASA’s astronaut program.  That said, I still don’t know how a man who had once had a ticker-tape parade through New York in his honour later managed to lose the vice-presidential race to career politician and sometime lawyer Walter Mondale, a man who would later go on to suffer one of the biggest landslide defeats in US presidential election history.

Walter Mondale is of Norwegian descent, and the ancestral family home is the village of Fjærland, on a tributary of the Sognefjord, which gives me an extremely tenuous reason to end with one of my own photographs, taken a mere ten miles or so downstream from chez Mondale in 2010.

Sognefjord, 2010. (Image credit: me.)
Sognefjord, 2010. (Image credit: me.)

1966  –  Launch of Gemini X (command pilot John W Young and pilot Michael Collins) from Cape Canaveral launch site LC-19.  This was the sixteenth manned American spaceflight.


1997  –  Death of Eugene Shoemaker, astrogeologist, and co-discoverer of comets (along with his wife and David Levy).  Of their combined tally, the most important was  probably Shoemaker-Levy 9, which collided with Jupiter in 1994.


July 15 – Dame Jocelyn Bell Burnell

Today is the birthday of Professor Dame Susan Jocelyn Bell Burnell DBE, born July 15th 1943 in Belfast, Northern Ireland. Dame Jocelyn was the the discoverer of the first four pulsars, and, rather disgracefully, a non-recipient of the Nobel Prize for her efforts, which has annoyed a great many people, although Bell herself has been very forgiving, as one would expect from a good Quaker girl.


1890 – Asteroid 294 Felicia was discovered by Auguste Charlois.


 

July 08 – Discovery of Jupiter’s Moon, Adrastea (1979)

Adrastea, the second moon out from the “surface” of Jupiter, was discovered by analysis of Voyager 2 images in 1979 by David C Jewitt and G Edward Danielson.  A subsequent photograph is available (the Voyager one was of a tiny speck) taken by the Galileo spacecraft, and here it is, looking more like an out-of-focus lemon than a moon . . . .

Adrastea (image credit: NASA)
Adrastea (image credit: NASA)

Adrastea is like the Earth’s Moon, in that it always keeps one face pointing towards the parent planet, but it has an unusual orbital period of 7 hours 9 minutes, which is about two hours less than one Jovian day, even though Jupiter has the fastest rotation of all the planets (which accounts for its easily visible bulge).  Only a very few moons do this (three are known, the others being Metis and Mars’ moon Phobos).  As I mentioned two days ago, we can tell without looking it up that Adrastea will have a prograde orbit, because it ends with an “a”.

Metis and Adrastea share another unusual fact in common.  They orbit too close for comfort to their parent, meaning that at some point in the future they will impact the planet.

In Greek mythology, Adrasteia was the nymph who had to nurse Zeus and hide him from his father, Kronos.  Her name means “inescapable”.


1695   –   Death of Christian Huygens.


1959   –   Launch of Explorer 6.


2011   –   Final launch of shuttle Atlantis (flight number STS-135).


July 04 – Birth of Henrietta Swan Leavitt (1868)

American astronomer Henrietta Swan Leavitt, the woman indirectly responsible for making Earth a much smaller and less important place,was born today in 1868.

Leavitt worked at Harvard College Observatory as a “computer”, measuring and recording the brightness of stars. She worked on variable stars in the Magellanic Clouds, and noticed that the luminosity of a star and its period were linked. This discovery, the period-luminosity relationship , eventually led Edwin Hubble to the conclusion that spiral nebulae are actually galaxies, thus making the Universe a whole lot bigger, and showed Harlow Shapley that the Sun is in the galactic suburbs, and not, as had previously been suspected, at the centre of the action.


July 02 – Birth of Hans Bethe (1906)

The happy chap in the photograph is today’s birthday boy, German-born (later American) nuclear physicist, Hans Bethe.

Hans Bethe
Hans Bethe

Born in Strasbourg in 1906, Bethe majored in chemistry at Strasbourg University for a while, but was tempted to Munich in 1926 by the superior standard of physics there. After obtaining his doctorate, Bethe took up a couple of posts in Germany, before obtaining a traveling scholarship from the Rockefeller Foundation. This enabled him to work at the Cavendish Laboratory in Cambridge, and then for Enrico Fermi in Rome. A year in Manchester was followed by Bethe taking up a post at Cornell University in 1935.

Like many eminent nuclear physicists of the 1940s, Bethe was involved in the development of the atomic bomb, and later the H-bomb (although he claimed to be opposed to it).

From our perspective, though, it is Bethe’s work on theoretical astrophysics that gets his photo at the top of this page. In 1967 he was awarded the Nobel Prize in Physics, and his work on the thorny problem of how electron neutrinos convert to muon neutrinos is remarkable, and even more so when one considers that he was in his 80′s at the time.  Muons, despite the protestations of my Ubuntu spellchecker, do exist, but only for a tiny fraction of a second.  They are like electrons, but with a greater mass. Muons are leptons (a word my spellchecker is happy with).

Basically, the so-called solar neutrino problem was a discrepancy between the number of electron neutrinos passing through the Earth and the number predicted by models of the Sun’s interior. I don’t think we need go into it too much, but the solution was that supposedly massless neutrinos aren’t massless after all, and can change from one type to another.

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June 29 – Birth of George Ellery Hale (1868)

Born today in Chicago, 1868, son of a genius (an elevator manufacturer in 19th century Chicago – what other word could describe him?), George Ellery Hale was a busy man. As well as being professor at Beloit College and the University of Chicago, he was author of several books, many papers, editor of the Astrophysical Journal and played a large role in founding Caltech.

In 1908 Hale showed that sunspots are magnetic. He followed this up by proving their East-West alignment, and their tendency to switch polarity between sunspot cycles. This work alone, as his obituary in the journal of the Royal Astronomical Society of Canada points out, would have been enough to gain him a place among the greats of astronomy, but it was his drive to organise others into building ever better and bigger telescopes that has assured his legacy (we will here skip ever so quickly over the alleged small elf, who apparently told Hale how best to persuade Rockefeller to cough up the six million dollars needed for his largest telescope; after all, who am I to tell a visionary genius what he can or can’t see?).

George Ellery Hale
George Ellery Hale

Hale’s quest for large telescopes led to some of the biggest ever. They included: the 60″ telescope at the Mount Wilson Observatory, near Pasedena, used to measure the size of the Milky Way and find our position in it; the 100″, also at Mount Wilson and completed in 1917, used by Edwin Hubble to study galactic velocities; and the monster 200″ at Palomar Mountain, southeast of Pasadena, with its 40 ton pyrex mirror. Unfortunately, due to the unbelievable complexity of building such a device, Hale had died long before Hubble made the first exposure in 1948.


1851  –  Discovery of asteroid 15 Eunomia, the largest S-type asteroid, by Annibale de Gasparis.  Eunomia is elongated in shape, and over 300km across at the widest point. In Greek mythology Eunomia was the goddess of lawfulness and good governance. Her nemesis was Dysnomia.


1888  –  Birth of Alexander Friedmann, Russian physicist, who came up with the Friedmann equations, to explain the expansion of the universe.