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 18 – Epimetheus

Saturn’s moon Epimetheus, discovered today in 1966 by Richard Walker, is a non-identical twin.  It, and its larger brother, Janus, which had been discovered three days previously by Audouin Dollfus, fly round Saturn in almost identical orbits (their mean orbital radii differ by a mere 50km or so).  Obviously, at the time of discovery, with only  the evidence of Earth-based telescopes to go by, this caused a certain amount of confusion among astronomers trying to work out where the supposed new single moon was.  At the time it was thought, also fairly obviously,  highly unlikely that two moons would share the same orbit without hitting each other.

Epimetheus from the Cassini Orbiter (image: NASA/JPL/SSI)

Epimetheus from the Cassini Orbiter (image: NASA/JPL/SSI)

It is possible that at some time in the past Epimetheus and Janus were part of a single larger body, but if that is the case it is likely to have been a very long time ago.  Both are heavily cratered, and their surface features display softening of their edges by the accumulation of dust, suggesting nothing much has changed there for some time.

Epimetheus was, in Greek mythology, a Titan (nowadays the name of a rather larger Saturnian moon), brother of Prometheus (also a moon of Saturn).  The pair were sons of Iapetus (another Saturnian satellite).  Epimethius was, according to some myths, married to Pandora (and guess what she gave her name to?).

Epithemius was given the job, shortly after the creation of the Earth, of finding a positive trait to give to each of the newly designed animals.  Unfortunately he ran out of good characteristics with one animal remaining, which you’ve probably already guessed was man.  That’s when Prometheus came along and gave  man the gift of fire, after which it all went downhill.

Epimetheus (3rd left) meets Pandora for the first time.

Epimetheus (3rd left) meets Pandora for the first time.

As it happens, though, they do share the orbit, and they don’t hit each other.  One moon does catch the other up every four years, but interactions between their gravities causes the inner moon to move faster (which causes it to move to a higher orbit) and the outer moon to slow down, causing its own orbit to drop a little.  So they actually exchange places, which is why I’m not going to call them the fifth and sixth moons, because they are each neither and both.


Launch, in 1958, of SCORE, the world’s first communications satellite (Signal Communications by Orbiting Relay Equipment).  The launch, from Cape Canaveral, was via an Atlas-B 10B rocket.

December 15 – Janus

J R Hind discovered today’s main belt asteroid, 23 Thalia, from Hyde Park, London, on December 15th, 1852 (I’d like to see him try that nowadays). Thalia is an S-type asteroid of about 107 km diameter, located between the 3:1 and 5:2 Kirkwood gaps.

In Greek mythology, Thalia, daughter of Zeus and Mnemosyne, with a name derived from the verb “to flourish”, was the muse of comedy and pastoral poetry. She may or may not (depending on which source you believe) have been the mother of the Corybantes, attendants to the Great Mother of the Gods, and associated with particularly orgiastic rites.


We also have a moon today.  The discovery of Janus, one of the inner Saturnian satellites, is attributed to Audouin Dollfus, who first observed it on December 15th 1966. Three days later, Richard Walker also observed an object in the right place but at the wrong time, which caused confusion for a while, but was eventually found to be another moon, Epimetheus, which shares an orbit with Janus.

Janus, photographed by the Cassini probe (image credit: NASA / JPL / SSI)

Janus, photographed by the Cassini probe (image credit: NASA / JPL / SSI)

Janus is the two-faced Roman god of beginnings, entrances, gates, doors, etc. You should thank him the next time an automatic door opens for you. Janus is also one of the select group of deities after whom a month (January) is named, and strangely he has no Greek counterpart.


1965  –  launch of San Marco 1 by Italy. Being their first satellite, the Italians wisely did not fill it with lots of expensive equipment. It did, though, contain a couple of experiments to study the ionosphere, the layer of the atmosphere stretching from about 60 km to 1,000 km, a region you need to know about if you’re planning to become a space-faring nation, needing to send radio messages over great distances.


2000  –  Death of George Alcock, aged 88, hunter of novae and comets. I believe he found five of each (remarkable for south-eastern England), some of them from indoors using binoculars, and even occasionally through double glazing1!  His eyesight must have been unbelievable.


2014  –  Voyager 1 crossed the termination shock.


 

2015  –  Launch of Expedition 46 to the International Space Station.  This caused considerable press interest in my homeland (in fact I’m going to call it a frenzy) because in addition to Russian cosmonaut Yuri Malenchenko and American astronaut Tim Kopra, the three-man crew contained Tim Peake, the first Briton to float into the ISS (I was going to say “set foot aboard” the ISS, but I’ve seen the footage, and feet don’t feature much).  Because of the  numbering system they use at the ISS when crews overlap, these three also formed part of Expedition 47.

ISS Expedition 46 Patch

ISS Expedition 46 Patch

As a supporter of Port Vale FC, I was distraught to discover that one of Tim Peake’s tasks whilst on this mission was to unveil a flag featuring the name of our local rivals, Stoke City.  I’ve gone off him a little.


 

1   Journal of the British Astronomical Association, vol.111, no.2, p.64-66

December 14 – Tycho Brahe

Tycho Brahe was born today in 1546 in Denmark. As the child of a wealthy family (he was born in a castle) he was well placed to receive a good education, and took up astronomy while studying law.

Tycho Brahe wearing the Order of the Elephant (and the Moustache of the Walrus)

Tycho Brahe wearing the Order of the Elephant (and the Moustache of the Walrus)

Tycho made several leaps of the imagination, including the development of his own model of the solar system, which he nearly got right. He correctly deduced that the Moon orbits the Earth, and that the planets orbit the Sun. unfortunately he also decided that the Sun must orbit the earth; an easy mistake to make I suppose at that time, if you spend your entire life seeing it cross the sky thousands of times in front of your very eyes.

Tycho was also the first person to decide that novae (they weren’t called that at the time) originated further away than the Moon. The popular view was that the stars were fixed and unchanging, and anything that appeared in the sky had  to be closer than them. But Tycho noticed that a bright new star in Cassiopeia (now called SN1572) did not move against the background stars, and so must be farther away than all the objects that did. It sounds fairly reasonable to us, but in the 16th century the night sky was anything but obvious.


2009 – Launch of the Wide-field Infrared Survey Explorer (WISE) by NASA, on a mission  to map 99% of the sky. So far, it has found more than 33,000 asteroids and comets, over 200 Near-Earth Asteroids (including 43 potentially hazardous ones), the most luminous galaxy in the known universe, and numerous brown dwarfs.


2013  –  the Chinese Chang’E 3 mission lands on the Moon.

The Chang'E Lunar Lander, imaged by the Yutu rover (image: China National Space Administration)

The Chang’E Lunar Lander, imaged by the Yutu rover (image: China National Space Administration)

 


 

December 12 – Uhuru

Uhuru, also known as the X-Ray Explorer Satellite or SAS-1 (for Small Astronomical Satellite) was an orbiting observatory, specifically for X-ray astronomy (the first of its kind). It was launched from the Italian San Marco offshore launch platform off the coast of Kenya on December 12th 1970, Kenyan independence day, hence the post-launch choice of a new name, which, as all good Star Trek fans know, is the Swahili for “freedom”. Its three year mission was to seek out new X-ray sources via a survey of the entire sky.

Uhuru (image credit: NASA)

Uhuru (image credit: NASA)

Uhuru was the first US satellite to be launched by another country.  Under the terms of a memorandum of understanding between NASA and the University of Rome, the Americans provided the rocket and satellite, while the Italians were responsible for the assembly and launch (following training with NASA in Virginia). The site was chosen principally to enable easier access to an equatorial orbit than would be possible from Cape Canaveral (which would have needed a much larger rocket).

The joint mission was very successful, with Uhuru producing a catalog of some 300 X-ray objects during its three years, mostly binary systems and supernova remnants.

On a completely unrelated topic that has nothing at all to do with astronomy or spaceflight, but might appeal to Star Trek fans of a certain vintage, December 12 1970 is also notable in Twin Peaks circles, as it marks the birthday of Mädchen Amick (Shelley Johnson).

December 04 – Gemini VII

We have slightly odd numbering here. Gemini 7 (VII) was launched on December 4th, 1965, after Gemini 5, but before Gemini 6A. Gemini 6 was obviously originally planned to go between 5 and 7, but had to be cancelled and rescheduled with an “A”.

The crew of gemini VII (Lovell, left, and Borman)

The crew of Gemini VII (Lovell, left, and Borman)

The plan for Gemini 7 was to observe the effects of prolonged spaceflight on astronauts. The two-man crew, Frank Borman and James Lovell, circled the globe 206 times during their two week confinement. After 11 days they were joined briefly by Walter Schirra aboard Gemini 6A, and practised rendezvousing (at closest approach they were just one foot apart).

Gemini, of course, is the constellation that lies between Cancer and Taurus in the sky (and therefore in the zodiac) and is historically associated with the twin brothers Castor and Polydeuces (or Pollux if you prefer the later Roman name).  I prefer Polydeuces myself, because the translation is “much sweet wine”, which you just don’t get with “Pollux”.  Castor, as any rodentologist will tell you, is Greek for “beaver”.

The Diskouri, in the Museum of Modern Art (image credit: Marie-Lan Nguyen)

The Diskouri, in the Museum of Modern Art (image credit: Marie-Lan Nguyen)

The twins now immortalized in the heavens were collectively known to the Greeks as the Diskouri, or “sons of Zeus” (the noun Gemini is from Roman mythology).  They also had twin half-sisters, even more famous than themselves: Helen (of Troy) and Clytemnestra.

 

December 02 – SOHO / BBXRT

Built in Europe, the Solar and Heliospheric Observatory (SOHO) was launched on December 2nd, 1995 (and is still going, despite being planned as a two year mission).  It is a joint project between ESA and NASA, designed to provide data to help predict solar weather, and answer questions about the solar interior and corona.  The mission has been a great success, providing significant insights into such areas as the structure of sunspots, the flow of gases inside the Sun, and the dynamics of the solar wind.

Prominence spotted by SOHO (image: ESA / NASA)

Prominence spotted by SOHO (image: ESA / NASA)

In addition to all this, SOHO has still found time to become history’s greatest ever discoverer of comets, with the total ticking over to an astonishing 3000 on September 13th 2015.  Comet number 3000 was spotted by Thai astronomer Worachate Boonplod, part of an amateur army of spotters who betwen them have been responsible for the majority of SOHO discoveries.


The Broad Band X-ray Telescope (BBXRT) was launched today (1990) on board shuttle Columbia flight STS-35. It formed part of the partly-successful “ASTRO-1” payload of four instruments.

 

In-flight view of BBXRT (image: NASA)

In-flight view of BBXRT (image: NASA)

The mission was somewhat shorter than the previously-mentioned SOHO, as the telescope was attached to the shuttle, and had to go wherever it went (back to Earth).

November 29 – Mercury-Atlas 5

Mercury-Atlas 5 is classed as an unmanned flight, launched from Cape Canaveral on November 29th, 1961. And yes, I suppose that it was technically unmanned, because there were no men on board. But there was an astronaut, and that astronaut was male.

ENOS in his launch position. (Image: NASA)

ENOS in his launch position. (Image: NASA)

Enos, pictured above, was the second chimpanzee to fly into space, and the first to orbit the Earth. The idea behind Enos’ trip was to stage a flight that would be as close as possible to the planned MA-6 launch, but without John Glenn.

Enos survived his odyssey, but it was touch and go. A problem with the environmental controls made it rather warmer than planned in the capsule, and fuel consumption concerns led to the intended three orbits being curtailed at two.

The World’s most travelled chimp lived for just under a year following his triumphant return to Earth, and died of dysentery on November 4th, 1962. It is not known what became of his remains. And if you still think I’m being silly and sentimental by suggesting that MA-5 should be called a manned trip, the name Enos (a biblical name, one of the grandchildren of Adam and Eve) means “man”.

November 20 – Swift

The Swift Gamma Ray Burst Explorer was launched on November 20th 2004 by NASA as part of their medium-sized “MIDEX” program (or grande if you’re a Starbucks drinker).  Now the first thing you’re probably thinking is “why isn’t the name Swift in capital letters?”  The answer is that Swift is not an acronym.  It doesn’t mean anything (except that you’re supposed to think of a small, fast bird).

Swift (image: NASA)

Swift (image: NASA)

If you look at some of the early press releases about Swift, NASA were hopeful that it would last for the duration of its two year mission, and survey over 200 gamma ray bursts (GRBs).  Now, 11 years later, and with over 1000 GRBs under its belt, Swift has exceeded all expectations and is still going strong.

Gamma rays are extremely high frequency emissions formed by the decay of atomic nuclei, and a burst of gamma rays is exactly what it sounds like: in a Universe where most things happen over millions of years, GRBs are astoundingly quick.  Slow ones can take a couple of hours; but the quickest have been and gone in a few milliseconds.  Also, there are only a few every million years in an average galaxy, which you might think would make them hard to spot, but fortunately they are so unbelievably powerful that the energy has no problem travelling the millions or billions of light years between the source and the detectors on board Swift.

One of Swift's collection: GRB 090429B, 13 billion light years away (image: NASA)

One of Swift’s collection: GRB 090429B, 13 billion light years away (image: NASA)

Swift has observed some pretty unusual events over its lifetime, including the most distant GRB ever seen, an x-ray source right in the centre of the galaxy, and a two-week long blast of stellar flares from a red dwarf reckoned to be 12 times hotter than the centre of the Sun.