May 30 – Messier 12

Today’s main event is not dissimilar to yesterday’s. It happened in 1764, and was the discovery of a globular cluster, Messier 12, (or NGC 6218), by Charles Messier, one day after he discovered globular cluster M10. And at a casual glance, the photograph I’m using today looks remarkably similar to the one I used yesterday. But I’ve had a close look, and they definitely two different balls of stars.

Messier 12 from the Hubble Space Telescope (image credit: NASA / STScl / ESA)
Messier 12 from the Hubble Space Telescope (image credit: NASA / STScl / ESA)

M12 is approximately 75 light years across, at a distance from Earth of about 15,700 light years. It can be located as a faint fuzz in the constellation Ophiuchus with good binoculars, but needs a fairly hefty telescope to bring out detail.

Location of M12 (image created using Stellarium)

I suppose the obvious question, with M10 on the 29th of May and M12 on the 30th is: what about Messier 11? Unfortunately for Charles M11 had already been discovered. He included it in his catalogue, but German astronomer Gottfired Kirch beat him to it by a mere 63 years. M11 is in the constellation of Scutum (the shield), and is commonly known as the “Wild Duck Cluster”.

Extrasolar planet MOA-2007-BLG-192Lb (or just MOA-192b to its friends) was discovered orbiting the low mass red dwarf of the same name (but without the “b”) on May 30, 2008. Spotted by the MOA-II gravitational microlensing survey, it is one of the smaller known extrasolar planets (about 3 times the mass of Earth) and has an appropriately tiny parent star of about 6% the size of the Sun.

1903 – Asteroid 511 Davida discovered in 1903 by R S Dugan and named after astronomer David Peck Todd.

2007 – Saturn’s tiny moon Anthe was first spotted in Cassini images. Anthe may be part of a dynamical family with the moons Methone and Pallene. This is appropriate if true, as they were sisters in mythology, three of the Alkyonides, who threw themselves into the sea when their father was killed by Herakles.

1963 – Happy birthday Helen Sharman, OBE, Sheffield native, chocolate chemist and first Briton in space. She flew on Soyuz flight TM-12 to the Mir space station. It was her only mission.


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 (
Location Chart for M104. image credit: Free Star Charts (

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 11 – Messier 2

M2, or NGC 7089, is a globular cluster of about 150,000 stars in Aquarius. It was discovered twice: firstly by Jean-Dominique Maraldi on September 11th 1746, and again on the same date 14 years later (1760) by Charles Messier.

Messier 2 (aka NGC 7089)
Messier 2 (aka NGC 7089)

M2 is fairly large, as globular clusters go, at 175 light years across, a little more elliptical in shape than most, and quite elderly (13 billion years old). It is also heading slowly in our direction, at 5.3 km/second. ‘Slowly’, of course, is relative to other intra-galactic speeds. Travelling at three miles a second would be plenty fast enough to get you a speeding ticket down here, but up there it’s nothing special.

(image from
(image from

Theoretically, M2 is a naked eye object if the sky is dark enough, but in practice that doesn’t apply round here in the land of the midnight security lamp. I need at least the small ‘scope to see anything.

Asteroid 125 Liberatrix, discovered by Prosper Henry (or possibly Paul Henry: you can never be sure) on September 11th 1872. It appears to be an M-type, and is possibly the biggest remnant of a larger body.

As for the name, the theory is that it honours Adolphe Thiers, president of the French Republic and suppressor of the Commune, who had recently been instrumental in extracting France from the Franco-Prussian War, in which they were doing none too well.

Asteroid 202 Chryseïs was discovered on this very day in 1879 by C F H Peters. It is about 86 km in diameter, and completes one full rotation every 16 hours as it travels at 17 km/second on its 5.4 year journey around the Sun.

Chryses visit to Agamemnon to ransom his daughter Chryseis (Image: Habib M’henni / Wikimedia Commons)
Chryses visit to Agamemnon to ransom his daughter Chryseis (Image: Habib M’henni / Wikimedia Commons)

In Greek mythology, Chryseïs (also known as Astynome) is indirectly the cause of most of the action in the Iliad. She is captured and enslaved by Agamemnon in Book One, and his refusal to allow her to be ransomed by her father, a priest of Apollo, eventually leads to all sorts of issues.

And while we’re talking of Apollo, asteroid 101955 Bennu was discovered on September 11th 1999 by the LINEAR project. It’s an Apollo, which means it has an orbit that brings it close to Earth, but in the case of Bennu not close enough to hit us (not yet, anyway). This proximity to Earth has led to Bennu being chosen as the target of the Osiris-REX “sample return” mission, which departed planet Earth in September 2016, and will return laden with souvenirs in 2023.

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 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.


April 04 – M85

1781  –  M85 (NGC 4382) was discovered on April 4th, 1781, by Pierre Méchain.

Messier 85 by the Hubble Space Telescope (image credit: NASA / ESA / STScI)
Messier 85 by the Hubble Space Telescope (image credit: NASA / ESA / STScI)

M85 measures approximately 125,000 light years across, and lies about 60 million light years away in the constellation of Coma Berenices. It is a member of the Virgo Cluster.

Location of M85 in Coma Berenices (image credit:
Location of M85 in Coma Berenices (image credit:

It is thought possible that M85 might be the result of two galaxies merging billions of years ago.

1858  –  Discovery by Robert Luther of Asteroid 53 Kalypso.

Kosmos 28 was launched on April 4th 1964.

1968 saw the launch, on this day, of Apollo VI to test the ability of the Saturn V to get an almost full payload to the Moon and back, and to repeat an earlier test of the Command Module’s heat shield. Apollo VI was the final unmanned launch of the program.

Launch of Apollo VI (image credit: NASA)
Launch of Apollo VI (image credit: NASA)

The flight was not without incident, caused in part by unusually strong vibrations shortly after lift-off. A couple of the engines shut down prematurely, necessitating a lower than expected “parking orbit”, and a lack of fuel on re-entry meant that the speed of a real lunar return could not be simulated.

March 27 – M101

Messier 101, also known as the Pinwheel Galaxy (NGC 5457) in Ursa Major, was discovered on March 27, 1781, by Pierre Méchain.  It is more than 20 million light years distant, contains around 1 trillion stars, and measures approximately 170,000 light years across (probably quite similar to the Milky Way, although our galaxy is hard to measure from the inside).

M101 (Image credit: ESA / NASA, Davide De Martin, and K.D. Kuntz)
M101 (Image credit: ESA / NASA, Davide De Martin, and K.D. Kuntz)

M101 has its own group of galaxies (called the M101 Group, obviously), and is one of a collection of groups of galaxies (including our own Local Group) that make up the Virgo Supercluster, a vast conglomeration of more than 100 groups of galaxies.

1886  –  Spiral galaxy NGC 2981, in the constellation of Leo, was discovered by Samuel Oppenheim (or possibly Johann Palisa – there is a little uncertainty).

1886  –  Barred Spiral galaxy NGC 2926 and spiral galaxy NGC 2944 (both in the constellation Leo Minor) were discovered by Johann Palisa.  These two are listed separately from the above NGC 2981 because they are definitely Palisa’s.

1906  –  Discovery of asteroid 594 Mirielle by Max Wolf at Heidelberg. It was named after a poem by the French poet Frédéric Mistral.  In the poem, written in the Occitan language, Mirèio is a farmer’s daughter who runs away from home to escape her father’s poor choice of suitors for her.

1964  –  Launch of Kosmos 27 on a planned trip to study the hostile Venusian atmosphere (when it would probably have been known as Zond 3MV-1 No 3). Unfortunately, an upper stage malfunction resulted in a mission duration of approximately one day, and a fiery death in Earth’s atmosphere.

1968  –  Death of Yuri Gagarin, hero of the Soviet Union, aged 34.