June 09 – Johann Gottfried Galle

Johann Gottfried Galle was born in the town of Radis, Germany, on June 9th, 1812. He was the first person to observe Neptune, knowing at the time that it was a planet. If you cast your mind back to a previous blog, you will recall that two men were on the hunt for Neptune simultaneously in the 1840s: English astronomer John Couch Adams , and Urban Le Verrier of France. It was Le Verrier who called on Galle with a prediction of the location of the new Trans-uranian planet while Couch’s guy was waiting for up to date charts to arrive.

While working at Berlin Observatory, Galle also discovered a new ring around Saturn and three comets.

Galle died at the grand old age of 98, on July 10th, 1910. He now has the innermost ring of Neptune named in his honour.

J G Galle
J G Galle

June 08 – Giovanni Domenico Cassini

On this day in 1625 the Italian mathematician and astronomer Giovanni Domenico Cassini was born in the tiny municipality of Perinaldo.

Cassini (Leopold Durangel, 1879).
Cassini (Leopold Durangel, 1879).

Cassini held several important astronomical positions during his career, including professor of astronomy at Bologna University, and director of the Paris Observatory, and was responsible for the discovery of four saturnian moons: Iapetus, Rhea, Tethys and Dione. He also discovered the Great Red Spot on Jupiter (at the same time as Robert Hooke, so he only gets half a credit for that one), and the “gap” in Saturn’s rings which now bears his name, the Cassini Division. I’ve put the word “gap” in inverted commas because recent visits to the planet have found it to be actually quite busy (see below).

The Cassini Division (image credit: NASA / JPL / Space Science Institute)
The Cassini Division (image credit: NASA / JPL / Space Science Institute)

Cassini wasn’t just a gas giant geek, though, and made observations of our nearest planetary neighbour, Mars, from Paris (simultaneously with a colleague a long way away in French Guiana to make the angle as big as possible) to make the first calculation of the size of the solar system using parallax. The relative positions of all the known planets had already been calculated, so only the distance to one was needed in order to have a stab at working out how far away they all were. Mars was the obvious choice because it’s the closest, so the apparent shift would be greatest. Cassini’s measurements turned out to be not too far from the values we have now; he used his observations to calculate the Earth-Sun distance as 21,700 “Earth radii”. Today we use the accepted value of 23,455.

1873: Main belt asteroid 146 Lucina discovered by Alphonse Borrelly, and named after the Roman goddess of childbirth.

1887: Themistian asteroid 268 Adorea discovered by Alphonse Borrelly.

2011:  Launch of Soyuz TMA-03M.


June 05 – John Couch Adams

English mathematician and theoretical astronomer John Couch Adams was born on June 5th, 1819, near Launceston, in Cornwall. Under the guidance of his maternal uncle, the Rev. John Couch Grylls, and using the facilities of the Mechanics’ Institute, Devonport, to further his studies privately, at the age of 2o he entered St. John’s College, Cambridge. He excelled at mathematics to the point of achieving the exalted position of Senior Wrangler (nothing to do with cows or denim, it’s the top scoring maths graduate of the year) in 1843.

Two years previously he had already begun to be intrigued by the possibility of a planet beyond Uranus, as the following nineteenth century “note to self” shows:

“Formed a design . . . of investigating . . . the irregularities in the motion of Uranus, . . . in order to find whether they may be attributed to the action of an undiscovered planet beyond it . . . “

Adams’ study of the perturbations of Uranus’ motion first led him to conclude that an unknown planet beyond Uranus, located at double the distance from the Sun, might exert the necessary influence on Uranus if it was big enough, and in the right place. Following his obtaining more precise observations from the Astronomer Royal, a more refined prediction of how to locate the eighth planet was made, which Adams took to Greenwich Observatory and left for the attention of the aforementioned Astronomer Royal.

John Couch Adams
John Couch Adams

At the same time, Urban Le Verrier had also been on Neptune’s trail, and had predicted a location within one degree of that determined by Adams. Unfortunately for the reputation of British astronomy, the lack of accurate star charts meant that looking for an object moving against the background involved a painstaking wait for two lots of observations to be undertaken, recorded and compared. But Le Verrier’s calculations were in the hands of Dr Johann Galle at the Berlin Observatory and, despite beginning his search two months later than the British team (led by James Challis), with typical German efficiency he discovered the planet on the first night of observation, through the rather obvious method of having accurate star charts to hand.

1885 – Discovery of asteroid 248 Lameia by Johann Palisa. Lameia is a main belt asteroid of about 49 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 1418.21351670694 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.

2002 – Discovery of trans-Neptunian object 50000 Quaoar. Potentially a dwarf planet (it has a diameter of about 1000 km, but more information on its mass is needed before a decision can be made) I’m mentioning it mainly because 50000 is a nice round number, and partly because Quaoar was the first TNO to be detected directly from Hubble Space Telescope images.


1980 – Launch of Soyuz T-2.

May 26 – Launch of EXOSAT

The European X-Ray Satellite (EXOSAT) was launched on May 26th 1983, and was operational until April 9th 1986, studying x-ray binaries, active galactic nuclei, and other x-ray sources. Personally I think the best thing about it was its bizarre orbit (from 120,000 mile apogee to 300 mile perigee), but there were other highlights of the three years, including the discovery of quasi periodic oscillations in LMXRBs and x-ray pulsars. I can sense that you are just dying to know what LMXRB stands for. It’s Low Mass X Ray Binary (low mass is a little misleading, generally meaning lower in mass than the Sun).

1969Apollo 10 splashdown. Tom Stafford, John Young and Eugene Cernan were recovered by the USS Princeton, about 400 miles from American Samoa, in the Pacific Ocean. Their 8-day mission had included four orbits of the Moon, as a rehearsal for “the big one”, which was to take place later the same year.

Recovery of the Apollo 10 capsule
Recovery of the Apollo 10 capsule

1826 – Birth, in Chelsea, of Richard Christopher Carrington, recipient of the Gold Medal of the Royal Astronomical Society. His work included the demonstration of the existence of solar flares, and their influence on our planet. He now lends his name to the numbering system for sunspot cycles.

Last updated: May 10, 2019.

May 22 – Discovery of Asteroid 41 Daphne

Asteroid 41 Daphne was discovered on May 22nd 1856 by Hermann Goldschmidt. It is a C-type (i.e. dark and mostly carbon), main belt asteroid, orbiting in 9:22 mean orbital resonance with Mars, meaning that every 9 times Daphne orbits the Sun (about 15,113 days) Mars goes round almost exactly 22 times, which is the same distance.

Daphne was a nymph who attracted the attention of the god Apollo. She wasn’t keen on his advances, though, and pleaded for help to her father, a river god. His bizarre solution to her problem was to turn his daughter into a laurel tree.

Apollo and Daphne, by Veronese.
Apollo and Daphne, by Veronese.

Asteroid 41 Daphne has a satellite, S/2008 (41) 1, named Peneius, after the river god mentioned above, discovered on March 28, 2008. Peneius orbits Daphne every 1.1 days.

Thomas Gold was born on this day in 1920. Gold was an Austrian-born astrophysicist, proponent of the steady state theory of the universe, whose family fled to Britain when the Germans invaded (his father was a wealthy Jewish industrialist) . The British government, compassionate and understanding as always, had him thrown into an internment camp as an enemy alien for the first two years of the war, but later relented and put him to work on radar development.

1900 – Asteroid 455 Bruchsalia was discovered by Max Wolf. It sounds like it might be an Italian sandwich, but this main belt asteroid is actually named after the German city of Bruschal.

Last updated May 09, 2019.

May 17 – Birth of Norman Lockyer

Sir Joseph Norman Lockyer was born on May 17th 1836 in Rugby.  He has two main claims to fame: founding the journal Nature (which I used to read occasionally until I realized I couldn’t understand a word of it) and the quite tricky discovery of the inert, colorless, tasteless, odourless gas helium, which, because he first identified it in solar spectra, he named after the handsome Greek god of the Sun, Helios.

Norman Lockyer
Norman Lockyer

1887  –  Asteroid 266 Aline discovered by Johann Palisa.  Aline is a C-type asteroid in the main belt, and measures a chunky 108(-ish) km in diameter.  According to the Dictionary of Minor Planet Names by Lutz D Schmadel, the name might be a nod to Linda (“Aline”) Weiss, one of the seven children of the director of Vienna Observatory, Edmund Weiss.  This is quite possible, because Palisa’s previous discovery (265 Anna) had been named for Weiss’s daughter-in-law.

Last updated: May 08, 2019.

May 11 – Discovery of Asteroid 11 Parthenope

Main belt asteroid 11 Parthenope was discovered by Annibale de Gasparis on May 11th, 1850. It is an S-type, and about 153 km across. Parthenope, in Greek mythology, was one of the Sirens. She did not take failure well, drowning herself when she failed to entrap Odysseus with her singing failed to entrap Odysseus.

Odysseus being taunted by Parthenope and her gang.
Odysseus being taunted by Parthenope and her gang.

Today’s visual accompaniment is a detail from an Attic red-figure stamnos (storage jar) of about 500 BC by the Siren Painter (can you guess why?) from the British Museum. One of the Sirens, presumably Parthenope, is shown hurling herself into the sea. I like the outstretched “Go on then – drown yourself” hand gesture of the guy at the tiller.

1871 – Today sees the discovery of one of the most beautiful sights in the known Universe (my opinion), the unbarred spiral galaxy Messier 104, more commonly known as the sombrero galaxy. M104 was a late addition to the Messier list, not being officially included until 1923. This spectacular object is about 28 million light years from us, and measures 50,000 light years in diameter.

Hubble Space Telescope image of M104 (Image credit: NASA)
Hubble Space Telescope image of M104 (Image credit: NASA)

The sombrero galaxy is extremely bright, with a strong x-ray source at its centre, indicating the presence of a black hole. The black hole was confirmed by spectroscopic results obtained by Hubble.

LOcation Chart for M104. image credit: Free Star Charts (freestarcharts.com).
Location Chart for M104. image credit: Free Star Charts (freestarcharts.com).

1823 – Birth of John Russell Hind, discoverer of ten asteroids and several variable stars.

1883 – Asteroid 233 Asterope discovered by Alphonse Borrelly.

1904 – Asteroid 536 Merapi discovered by G H Peters, and named after a mountain in Sumatra.

1916 – Death of German physicist and astronomer Karl Schwarzschild, the man whose work gave us the Schwarzschild radius, the size to which an object of a certain mass must shrink for its escape velocity to become equal to that of light (a black hole, for example). The Schwarzschild radius of the Earth is just under 1 centimetre.

Last updated: May 08, 2019.

September 13 – Babcock

Horace Welcome Babcock (fantastic name), astronomer and inventor, was born today in 1912, son of solar specialist Harold D Babcock.  Babcock junior was the chap who realised that changing the shape of mirrors can be used to reduce the distorting effect of turbulence in the Earth’s atmosphere on light from distant objects (called adaptive optics). Unfortunately he made this discovery in the 1950s, roughly 40 years before the technology to actually do it became available.

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Asteroid 12 Victoria, named after the Roman goddess of Victory (and possibly the queen of the same name) was spotted by John Russell Hind on September 13th 1850.  It’s an S-type, which you will recall are the stony asteroids, the second most common group, most of whom are congregated in the inner main belt.  Victoria has an apparent magnitude varying between 8.7 and 12.8, suggesting she is either elongated or binary.

Victoria the goddess was very important to the Romans (much more than her predecessor Nike had been to the Greeks).  I’m guessing this had something to do with her rôle in deciding who would be victorious in battle.

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Asteroid 104 Klymene is a Themistian asteroid, discovered by J C Watson on September 13th 1868. The Themistians are a family of C-type asteroids, named after 24 Themis (and including 62 Erato, coming up tomorrow).

Klymene and Hera
Klymene and Hera

The name Klymene (or Clymene) crops up quite a few times in Greek mythology, but one of them, an attendant to Hera, stands out in my mind as being the most likely candidate for today’s rock, when you consider that the asteroid named immediately before this one was 103 Hera. This particular Klymene was an Oceanid (daughter of Oceanus) and you can see her, with Hera, in today’s picture, a detail of a depiction of the Judgement of Paris from the Badisches Landesmuseum, Karlsruhle.

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March 04 – Messier 85

1781  –  Messier 85, a lenticular (elliptical if you prefer) galaxy, was discovered on this day in 1781 by Pierre Méchain.  It can be found in the constellation Coma Berenices (named after the Egyptian queen Berenice II) and is about 60 million light years away, making it the northernmost galaxy in the Virgo Cluster, a collection of somewhere between 1,200 and 2,000 galaxies, on the periphery of which is our own local group.

M85 (image credit: NOAO / AURA / NSF)
M85 (image credit: NOAO / AURA / NSF)

There are hundreds of beautiful photographs of all manner of galaxies on the internet, but M85 is very under-represented by legal entities with relaxed media sharing policies, hence the above.

1861  –  Asteroid 64 Angelina discovered from Marseilles by Ernst Tempel.  Angelina is an E-type (containing enstatite) with a very high albedo (0.28) compared to many other asteroids.  It is named after an astronomical station operated by the Hungarian astronomer Franz Xaver von Zach.  For discovering Angelina (and 65 Cybele) Tempel received the ‘Lalande Prize’ from the French Académie des sciences.

1892  –  M-type (mainly metallic) main belt asteroid 325 Heidelberga was discovered today by Max Wolf.  If you’ve been following these pages closely the choice of name should come as no surprise, being the location of most, if not all, of Wolf’s discoveries. Heidelberga is reasonably large, at approximately 75 km in diameter.  Fuller details of Heidelberga’s physical and orbital characteristics can be found in the NASA JPL Small-Body Database browser.

1904  –  Birth of George Gamow, cosmologist, and early champion of the Big Bang theory.

1923  –  Birthday of Patrick Moore, amateur astronomer extraordinaire.

This post originally appeared in 2015, and was slightly updated in 2017.


December 30 – Launch of RXTE

December 30th seems to be a thin day astronomically, but I did manage to find, in 1995, the launch of the Rossi X-Ray Timing Explorer from Cape Canaveral.  Bruno Rossi, after whom the satellite was named, was the discoverer of the first source of x-rays beyond the Sun.

Artist's Impression of RXTE
Artist’s Impression of RXTE

Over a sixteen year lifespan, RXTE did exactly what its name suggests: it timed variations in emissions from x-ray sources using three experiments (a proportional counter array, theHigh Energy X-ray Timing Experiment, and an all-sky monitor).

Also today, in 1924, Edwin Hubble announced to the world that the Milky Way is not the only galaxy.  Using the 100-inch Hooker Telescope at Mount Wilson, Hubble was able to calculate the distance to Cepheid variable stars in the Andromeda Galaxy using a technique devised by Harvard astronomer Henrietta Swan Leavitt.  At the time, “spiral nebulae” were assumed to be patches of dust or gas within the Milky Way, but calculating a distance to Andromeda of approximately 860,000 light years changed the scale of the Universe for ever.