August 16 – Asteroid 46 Hestia

Main belt asteroid 46 Hestia was discovered on August 16th 1857 from the Radcliffe Obsetvatory, Oxford, by N R Pogson. 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.


1873 – Discovery of asteroid 133 Cyrene.

1885 – Discovery of asteroid 249 Ilsa.

July16 – Launch of Apollo 11

July 16th 1969 is a fairly important day in spaceflight history.  It’s the day on which Neil A Armstrong, Michael Collins and Edwin “Buzz” Aldrin decided to get away from it all.  Their Saturn V rocket (SA-506), the fifth manned Apollo mission, blasted off from the Kennedy Space Centre at about half past one in the afternoon (Staffordshire Time) and may be the reason I have the vaguest recollection of my infant school gathering after dinner to watch a launch on the school television.

Launch of Apollo 11 (image credit: NASA)

Launch of Apollo 11 (image credit: NASA)

Also today, in 1990, Mark R Showalter, using old frames from Voyager 2, discovered Saturn’s walnut-shaped moon, Pan, in the Encke Gap of the A Ring (the outermost of the main bright rings).

Thanks to the Cassini probe, we now have images beyond the wildest dreams of Voyager scientists:

Pan, imaged by Cassini (credit: NASA/JPL-Caltech/Space Science Institute)

Pan, of course, invented the pan pipes. He was a pretty hot musician all round, but a little big-headed. The story goes that he challenged Apollo to a musical duel. Pan was good, but Apollo was better. Only one person listening to the contest believed that Pan had won. This was Midas (he of the golden touch). So annoyed was Apollo at this lack of musical taste that he changed Midas’ ears into something more appropriate: those of a donkey.

The Judgement of Midas (Peter Paul Rubens)

The Judgement of Midas (Peter Paul Rubens)

Now, correct me if I’m incorrect, but in today’s artistic offering, is Pan playing his own invention upside-down?

This post originally published in 2015.  Updated 2017. 

March 19 – 326 Tamara

1892   –   Asteroid 326 Tamara, discovered March 19 1892 by Johann Palisa.  It is a C-type asteroid of about 93 km wide in the main belt, named after Tamar the Great, Queen of Georgia.

Queen Tamar, and her father, George III of Georgia.

Queen Tamar, and her father, George III of Georgia.

1892  –  Asteroid 332 Siri was also discovered on March 19th 1892, but by Max Wolf at Heidelberg.  It’s a fairly small object, about 40km wide.  The origin of the name is not known, and I haven’t been able to find any likely candidates.  Part of the problem, of course, is that, as with the aforementioned Tamara, and the next on this page, Isara, the name could have been altered to fit some perceived idea of what an asteroid’s name should sound like.

1893  –  Asteroid 364 Isara was discovered by Auguste Charlois.  It is a member of the large Flora family of S-type asteroids, which may be parents of the L chondrite meteorites.  The Isère river, from which this asteroid derives its name, flows from the Alps and joins the Rhone near Valence in southern France.

1919  –  Karl Wilhelm Reinmuth discovers asteroid 911 Agamemnon, a “Greek camp” Jupiter Trojan of approximately 83 km radius (making it probably the second biggest).

Originally posted 2015. Updated 2017.


March 17 – Jim Irwin

March 17th 1930: astronaut Colonel James Benson Irwin, USAF, born in Pittsburgh PA.

James Irwin (image credit: NASA)

James Irwin (image credit: NASA)

In 1971 Irwin, Apollo 15 lunar module pilot, became the eighth man to walk on the Moon, spending over 18 hours on the surface.  He also, on his return, became one of the first people to be grounded, quite literally, for smuggling postage stamps into space.

1852  –  Asteroid 16 Psyche was discovered on March 17th 1852 by Annibale de Gasparis.  Psyche is a large asteroid, about 200 km in diameter, accounting for about 1% of the mass of the entire asteroid belt.  It’s an M-type asteroid, probably mostly nickel and iron.

Cupid and Psyche (Van Dyck)

Cupid and Psyche (Van Dyck)

Psyche is named for a mythological princess, who caught the eye of the god Cupid.  The story is told by Lucius Apuleius in The Golden Ass.

In early 2017 NASA announced plans to  send a probe to Psyche in 2023, as part of their Discovery Program, the main reason being that, as a metallic asteroid, it represents one of the few classes of objects in our neighbourhood that haven’t yet been visited.

1899  –  Saturn’s moon Phoebe discovered by American astronomer W H Pickering.  It, too, is about 200 km in diameter, and may be a captured centaur from the Kuiper belt.  We have some spectacular photographs of Phoebe following the visit of the Cassini spacecraft in 2004.

Phoebe (image credit: NASA)

Phoebe (image credit: NASA)



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.


December 27 – Johannes Kepler

Today is Johannes Kepler’s birthday.

Kepler was born in Weil der Stadt, a small town near Stuttgart, on December 27th 1571, and was introduced to astronomy from an early age, whether he liked it or not, by being taken outside to witness the Great Comet of 1577, C/1577 V1, at age 6. The comet was also seen, incidentally, by Tycho Brahe, with whom Kepler would later spend some time studying at the site of Brahe’s new observatory near Prague.

Johannes Kepler

Johannes Kepler

Kepler’s works included many revolutionary (and I mean that in several ways) publications on the behaviour of planets. His Astronomia Nova, published in 1609, contained arguments in favour of a heliocentric ‘universe’, and Harmonia Mundi (“The Harmony of the World”, 1619) was the setting for his third law of planetary motion.

As well as being an influential astronomer, Kepler was also a major influence in the field of optics (possibly because his own eyesight wasn’t the best). He was the first person to explain how a telescope works; worked out how our eyes perceive depth; investigated how a pin hole camera might be used to produce pictures, and discovered total internal reflection.

Also today, globular cluster Messier 92 was discovered in 1777 by Johann Elert Bode.

M92 (Photo courtesy of the Isaac Newton Group of Telescopes, La Palma)

M92 (Photo credit: the Isaac Newton Group of Telescopes, La Palma)

M92 is located in the constellation of Hercules. It is one of the oldest and brightest globular clusters, and is about 27,000 light years from Earth.

1968 – Splashdown, south of Hawaii, of Apollo 8, following a 6 day flight that included the first Earthrise seen by humans, and the first Christmas broadcast from a craft orbiting the Moon.


December 24 – Rhea

Saturn’s second-largest moon, Rhea, was discovered on this day in 1672 by Giovanni Domenico Cassini, who had presumably finished his Christmas shopping early.

Rhea from the Cassini probe (image: NASA / JPL / SSI)

Rhea from the Cassini probe (image: NASA / JPL / SSI)

Like our own Moon, Rhea always keeps one side, the one you can’t see in this photo, facing towards the parent planet, and from the above view of Rhea’s cratered anti-Saturnian surface, this does look to be a place very much like the Moon we are familiar with down here.  But appearances can be deceptive.  For a start, it’s a lot smaller than the moon, and if it soft-landed on the Earth it would fit quite comfortably inside the borders of Zaïre (in this country people usually use Wales as the benchmark for large areas, but I felt like a change).  Secondly, although it looks nice and rocky, Rhea is thought to be comprised of as much as three-quarters ice, and only one quarter rock (studies of Rhea’s inertia suggest that it doesn’t even posses a rocky core).

Rhea is named after a Titaness of some standing, the daughter of Uranus and Gaia.  As mother of Zeus and Hera, she was grandmother or great-grandmother to almost all the Olympian gods and goddesses worth mentioning.



There are several suggestions doing the rounds concerning the origin of the name Rhea.  It may derive from the word for “flow”, or it could have a root in a much older word for “powerful”.  But the guy who named the large, flightless, South American bird after her was almost certainly thinking of a derivation of the Greek έρα, meaning “ground”.

Another Rhea

Another Rhea



December 22 – Asteroid 264 Libussa

Discovered on December 22nd 1886 by C H F Peters, asteroid 264 Libussa is an asymmetrical S-type main belt asteroid of somewhere between 50 and 60 km diameter.

It was named after Libussa (Lubossa or Libuše), a half-elf  daughter of the mythical Czech king Krok.  She eventually became the founder of the city of Prague, and ancestor of the whole Czech nation.

Libuse (photo credit: Palic Kap)

Libuse (photo credit: Palic Kap)

Today’s photo shows a detail from the Octárna Hotel, Kroměříž, Czech Republic.  This is alunette (a half moon shaped space) by local artist Max Švabinský. It shows Princess Libuse prophesying the glory of Prague.

There’s not a great deal more to say about Libussa, so it’s back to orbital characteristics.  To date we have come across aphelion (3.18 AU for this particular rock), perihelion (2.42 AU), semi-major axis (2.8 AU), longitude of ascending node (49.8°), and inclination (10.4°).  Today we add another important element of an asteroid’s orbit: the argument of perihelion.  For Libussa, this is 339.27°, and in orbital calculations it is depicted by the letter  ω.  It’s not a “w”, by the way, but a lower-case omega (the word means “great o”) the last letter of the Greek alphabet.  Remember that, because one of these days I’m going to work out how to put some of these calculations in this blog in the form of a table.

The argument of perihelion is the angle between the perihelion and the ascending node.  So if, for example, the value was 90°, that just means that the asteroid would be at perihelion when it reached the northerly point in its orbit.

1981  ⇒  Asteroid 323 Brucia becomes the first asteroid to be discovered by astrophotography, by Max Wolfe.


December 19 – Asteroid 397 Vienna

Asteroid 397 Vienna was discovered by Auguste Charlois on December 19th, 1894. It is an S-type main belt asteroid of about 43 km diameter. There are no prizes for guessing the origin of the name.

In the 1960’s, the only way to spy from above on your decadent imperialist western enemies was to send collections of cameras into orbit, shoot a few rolls of film, bring the whole thing back down, and hope you could make it land in a suitable place for retrieval.
Kosmos 24 (also known officially, but less publically, as Zenit 2, Number 15) was one such Soviet reconnaissance satellite, launched on December 19th, 1963, and recovered by the military nine days later. The launch took place at the Baikonur Cosmodrome via a Vostok 2 rocket, and as far as anyone is aware it was a success.

Kosmos 24

There were over 500 Zenit 2 launches, mostly carrying four cameras, with each camera capable of shooting 1500 frames. And what I didn’t know until very recently was that the Zenit camera I owned in the late 1970’s was made by the same company who manufactured the equipment for the Kosmos satellites. I Wish I’d kept it.

2013 – Launch of the Gaia Space Observatory.