July 13 – Discovery of Gamma Cephei Ab (1988?)

Gamma Cephei Ab was probably discovered on July 13,  1988 by Bruce Campbell, Gordon Walker and Stephenson Yang. But there was, understandably, a certain amount of uncertainty over whether they had, in fact, discovered the first extra-solar planet, so it wasn’t confirmed until more than a decade later.
The star Gamma Cephei is, of course, in the constellation Cepheus, named after a mythological king of Aethiopia. It is a binary system, comprising Gamma Cephei A, a “K” type star (the next most common type of main sequence star after the “M” types) and B, thought to be a red dwarf.

La Délivrance d'Andromède (1679) by Pierre Mignard.
La Délivrance d’Andromède (1679) by Pierre Mignard.

Today’s visual aid is from the Louvre, Paris, and shows King Cepheus (kneeling) and his queen, Cassiopeia, thanking Perseus for freeing their daughter Andromeda.  Completing the collection of Northern constellations, a certain winged horse can be seen palette-bombing in the background.


June 13 – New Planet and NuSTAR

Exoplanet Gliese 876d was discovered on June 13th 2005 by the California and Carnegie Planet Search.  It was found by using the radial velocity method of planet detection, and at the time of discovery was among the lowest mass planets yet detected.  Because of this it was placed in the “super Earth” category.

As it has only been detected indirectly, there is little to say about Gliese 876d’s physical characteristics, apart from “it’s probably terrestrial, rather than gaseous”.  Other parameters, such as the radius one and a half times that of the Earth, and a mass of almost seven Earths, are probably good working calculations, but they rely to a certain extent on assumptions that Gliese 876d works in a similar way to models of solar systems of a similar make-up.

The host star to today’s discovery, Gliese 876, is a red dwarf, 15 light years away from us in Aquarius. It has four known planets, of which “d” is the innermost.  The first to be discovered, Gliese 876b, is a whopper, estimated at over twice the mass of Jupiter.  All four are really close to their host, with none of them any further than Mercury is from our Sun.


NuSTAR, the Nuclear Spectroscopic Telescope Array, was launched this day in 2012 as part of the NASA “Small Explorer” program, to study the high energy x-ray end of the spectrum, armed with an ingeneous 33 foot (10 metre) long extendable mast to greatly extend the focal length (longer focal lengths are necessary to focus x-rays) without having to use a monstrous rocket to get it into orbit, as had been the case with previous 10 metre tubes.

NuSTAR (artist's conception). Image: NASA / Caltech / JPL.
NuSTAR (artist’s conception). Image: NASA / Caltech / JPL.

Asteroid 132 Aethra was discovered on June 12, 1873 by James Craig Watson. Aethra is a Mars crossing main belt asteroid, the first to be identified as such. It is approximately 43 km across, and has an absolute magnitude of 9.21. It is named after Aethra, daughter of King Pitheus of Troezen (a small town in the Peloponnese) and the mother of Theseus.


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.

December 19 – Tau Ceti ‘e’ and ‘f’

Tau Ceti e and Tau Ceti f are as yet unconfirmed exoplanets orbiting, fairly obviously, the star Tau Ceti, a G-type main sequence star in the constellation Cetus (usually referred to as “the whale”, but actually a sea monster from Greek mythology). They are the fourth and fifth planets out from the star, and were discovered on December 19th, 2012, by the “radial velocity” method, the oldest known means of detecting planets outside our system.

Location of Tau Ceti
Location of Tau Ceti

Both planets are likely to be a fair bit bigger than the Earth (“f” could be up to seven times larger), but they have excited astronomers by being in the habitable zone of Tau Ceti. It is thought they could have temperatures of up to 50 or 60°C, which is plenty warm enough for the existence of life. Unfortunately for any Tau Cetians though, the parent star is known to have an extensive “debris disk”, meaning that any planets nearby would face a regular pounding by rocks of varying shapes and sizes, almost certainly including some big enough to cause serious problems for any fledgling species trying to evolve.

October 16 – Asteroid 1500 Jyväskylä

1500 Jyväskylä  is a very small main belt asteroid, discovered by the Finnish astronomer Yrjö Väisälä on October 16th 1938.  Almost nothing else is known about this asteroid except its location and very approximate size (between 7 and 15 km in diameter).  Väisälä chose to name it after a city in the Lakeland region of central Finland.

Rowing boats on the shore of Palokkajärvi in middle Finland (image credit: Magnus Franklin).
Rowing boats on the shore of Palokkajärvi in middle Finland (image credit: Magnus Franklin).

Lake Palokkajarvi (above) is only 2km north of the city of Jyväskylä.

This is Väisälä’s only entry in these pages at present, but as he discovered a quite impressive number of asteroids (128) I’m going to add him to the list for a mention next year on his 124th birthday (September 6th).

2012  –  Discovery of exoplanet Alpha Centauri Bb using Dopler spectroscopy, by Xavier Dumusque and others at Geneva Observatory.



October 06 – 51 Pegasi b

October 6th 1995 was a significant day in the hunt for extrasolar planets, with the discovery, in the constellation of Pegasus (the winged horse), of the first one found to be orbiting a main sequence, Sun-like star. That star was 51 Pegasi, and the planet is known as 51 Pegasi b, shortened to 51 Peg b if you’re in a hurry, and lengthened (unofficially) to Bellerophon if you’re not. Bellerophon was the Greek character who tamed Pegasus, so you can see what they did there. The “b”, by the way, indicates that this was the first planet discovered around 51 Peg. There is no “a”, as that letter would be used, in uppercase, to denote the star itself, and would only be needed if the star had a companion (“B”).

Count them if you like.
Count them if you like.

The discovery of 51 Peg b was made using the radial velocity method, and announced by Michael Mayor and Didier Queloz. It was later confirmed by other observers (always important).

Despite orbiting a Sun-like star, 51 Peg b was still nothing like the type of place planet hunters were looking for (they all wanted to find an Earth-like planet at about the same orbit as ours). 51 Peg b is about 150 times the mass of the Earth, wider than Jupiter, is closer to 51 Peg than Mercury is to the sun, giving it a mean temperature of around 1,000°C, and has a year lasting about 4 Earth days. All of which has made me decide not to move there (my border perennials wouldn’t like it one bit).

Smallish asteroid 299 Thora is a fairly typical main belter, discovered on October 6th 1890 by Johann Palisa. It is about 17 km wide, and zooms around the Sun every 1,387 days at 19 km/second.

Thor wades through a river while the æsir take the bridge, by Lorenz Frølich
Thor wades through a river while the æsir take the bridge, by Lorenz Frølich

The name Thora was chosen by a Professor Schlieber of Berlin, after the Germanic and Norse god of thunder and lightning, Thor. According to Norse legend, Thor was the son of Odin, and husband of Sif (although, as with the Greek gods, this didn’t stop him fathering children by other women). Thor, as you probably aware, carried a hammer capable of flattening mountains, and had Thursday named in his honour.

So, if you know anyone named Thora, tell them they can blame it on their pagan Viking parents.

1964  –  The Soviet Union launches Kosmos 47, an unmanned Voskhod test flight.

1990  –  Launch of the NASA / ESA Ulysses probe to study the Sun.

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 17 – 17 Thetis

Today’s lump of rock, asteroid 17 Thetis, was discovered in 1852 by yesterday’s birthday boy, Robert Luther.  It was the first asteroid he discovered.

Thetis is a main belt asteroid approximately 90 km across, with an absolute magnitude of 7.76 (apparent magnitude from 9.9 to 13.5).

Not a great deal is known about Thetis, but it is thought to be an “S-type” asteroid (the S stands for stony).   S-types are the second most common asteroids after “C-types” (C = carbonaceous).

Black figure hydria showing Thetis and the Nereids mourning Achilles
Black figure hydria showing Thetis and the Nereids mourning Achilles

Most references to Thetis (goddess of water)  in Greek literature relate in some way to her role as mother of Achilles, the greatest warrior of the Trojan Wars, but she did have some adventures of her own, most notably protecting Zeus from a plot to overthrow him by summoning Briarius, a friendly “Hekatonkheire”, Greek for “hundred-handed one” (and just in case that wasn’t frightening enough, they had fifty heads as well).

2014  –  NASA announced the discovery of Kepler-186F by the Kepler mission, which is using the “transit” method to discover exoplanets.   Kepler had already discovered hundreds of planets, but this was the first Earth-sized planet, orbiting a red dwarf, to be spotted.  The Kepler team believes that red dwarf stars could provide the majority of “habitable zone” planets, and Kepler-186F is on the edge of the host star’s habitable zone, in an orbit similar to that of Mercury.

Kepler-186F, is, unsurprisingly, orbiting a star known as Kepler-186.  This is an “M dwarf” (the Sun is a “G dwarf”) about 500 light years away.  M dwarfs are the most populous type of star in the known universe (7 out of 10 stars fall into this category, even though they can’t be seen by the naked eye). M dwarf stars are much dimmer than the Sun, and smaller, some being only 8% the mass of our star.

Comparison graphic for Kepler-186F (image: NASA)
Comparison graphic for Kepler-186F (image: NASA)

We should probably resist the temptation to get too excited about the possibility of life on Kepler-186F.  It is not known whether it has an atmosphere, and NASA are uncertain as to whether the planet is “tidally locked”, which would be unhelpful to life, or subject to flares from the parent star, which would be fatal.   However, NASA say that the differences between the conditions on Earth and K-186F don’t rule out the possibility of life.

1861  –  Asteroid 67 Asia discovered by Norman Robert Pogson.

1888  –  Asteroid 276 Adelheid discovered by Johann Palisa.  The origin of the name is not known.  There were probably a few Adelheids (and Adelaides) around at the time, but the most high-profile was Princess Adelheid of Hohenlohe-Langenburg, a niece of Queen Victoria.  Unfortunately I can’t find anything spectacular happening in her life in 1888.  Another posibility though, is Princess Helena Adelaide of Schleswig-Holstein-Sonderburg-Glücksburg, born in 1888 (the name Helena had already been taken for an asteroid discovered by  J C Watson in 1868).  Who can say?

1970  –  Splashdown of Apollo 13, following the scariest mission of the entire manned Apollo program.

View of the Moon from Apollo 13 (image credit: NASA).
View of the Moon from Apollo 13 (image credit: NASA).

February 14 – Luna 20

Launched this day in 1972, Luna 20 was part of the Soviet Union’s unmanned answer to the USA’s manned Moon missions.  The main aim was to return samples to Earth, and Luna 20 was the eighth mission to attempt this.  It’s mission was to finish the job that Luna 18 was supposed to have completed  the previous September.  Luna 18, however, had ceased transmitting as soon as it hit the Moon, suggesting a less than perfect landing.

Luna 20 returns home
Luna 20 returns home

Luna 20 was more successful.    It landed in the Apollonius highlands, near the Mare Fecunditatis (Sea of Fertility) on February 21st.  Holiday snaps were taken with the panoramic camera, and the on-board drill took some soil samples (55 grams).  These were launched back to Earth the next day and landed near the copper mining town of Jezkazgan, (now in Kazakhstan, but at the time in the USSR) on Feb 25th.

On this day in 2008, OGLE-2006-BLG-109 Lb was discovered.  Yes, I know, it’s not the easiest name to remember, but it is slightly more exciting than it sounds.  OGLE-2006-BLG-109 Lb is an extra-solar planet, orbiting the star OGLE-2006-BLG-109 L in Sagittarius (which means that to avoid writing it again I’m just going to use the “b” as the name of the planet).  It is believed that the solar system to which “b” belongs has some planets similar in size to Jupiter or Saturn, and possibly some more Earth-sized.    “b” was discovered using a technique called gravitational lensing (“OGLE” stands for Optical Gravitational Lensing Experiment).

And finally, it wouldn’t be the same without an asteroid, so we announce that on February 14th 1891, Johann Palisa added 304 Olga to his collection. It was named by the Prussian astronomer Friedrich Wilhelm Argelander in honour of his niece.


February 03 – Luna 9

Feb 3rd is a big day in spaceflight history, because on this day in 1966, the Soviet Union successfully soft-landed  Luna 9 onto the Moon, beating the USA by just over 4 months, and no doubt causing wide grins and double vodkas all round in Moscow.

Luna 9 was launched from the world’s oldest space centre at Tyuratum in Khazakstan.  The centre is still being used by the Russians, although today they have to lease it from the Khazak government (how are the mighty fallen).

Luna 9
Luna 9

The flight to the moon took 79 hours, after which the main spacecraft ejected a small (2 foot diameter) capsule weighing 220 lb (100 kg) which, thanks to the ingenious use of retro rockets, airbags, outrigger engines and a 16 foot long probe which told the engines to cut out when it touched the surface, hit the Moon at a sedate 14 mph, and only needed to bounce a few times before righting itself (it was weighted in such a way as to come to rest the right way up).  The four “petals” covering the top half of the craft then opened up and became stabilizing legs (as in the photo of the still futuristic-looking-after-all-these-years Luna 9, above).   Landing occurred in the Oceanus Procellarum at 9.45 PM Moscow time.

Three panaoramic photographs were transmitted back to Earth over a three day period.   They were picked up by Jodrell Bank Observatory in Cheshire, and decoded thanks to a receiver provided by the Daily Express newspaper (see below).

Photograph of the Moon from Luna 9
Photograph of the Moon from Luna 9

2008   ⇒   On this day in 2008 the extrasolar planet Corot-3b was discovered in the constellation of Aquilla by the French-led COnvection ROtation et Transits planétairesmission using the transit method.

1921   ⇒   Happy birthday Ralph Asher Apher, cosmologist, born today in Washington DC.  A big name in the world of big bang nucleosynthesis, which sounds like heavy stuff, and is, as it describes how heavier elements would be created in the primordial universe).