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 06 – Pioneer 3

Launched from Cape Canaveral on December 6th 1958, Pioneer 3 was supposed to be a lunar flyby. Unfortunately that didn’t happen, but the craft did manage to reach a distance from Earth of about 63,000 miles, and used its Geiger-Müller tubes to gather useful information about the Van Allen radiation belt.

Pioneer 3 (image: NASA / JPL)

Pioneer 3 (image: NASA / JPL)

Pioneer 3 ended its one day flight by burning up over Africa.


1888   –   Birth of comedian and astronomer Will Hay in Stockton-on-Tees, North East England.  In 1933 he discovered a Great White Spot on Saturn in August 1933 (note: it’s “a” not “the” Great White Spot, as there have been several observed over the past century).  At his home in Norbury, South London, Hay built his own observatory to house his 1895-vintage 12.5 inch Newtonian reflector and the 6-inch refractor he used to discover the white spot.


1893   –   Discovery of asteroid 378 Holmia by Auguste Charlois (the name is the Latin for Stockholm).


1998   –   Launch of the Submillimeter Wave Astronomy Satellite (SWAS).  One of NASA’s SMEX (Small Explorer) missions, SWAS was intended to have an operational life of two years, but managed to stretch to six, studying the cores of interstellar clouds to help our understanding of what they are composed of, and how they cool and collapse to form stars.


 

November 02 – Asteroid 13 Egeria

Annibale de Gasparis discovered today’s asteroid, 13 Egeria, in 1850, named some time later by Urbain Le Verrier in honour of an Italian nymph.

Egeria is, as usual, in the main belt, but is a G-type, not something we get in these pages every week.  G-types are similar to C-types, but are thought to contain phyllosilicates such as clays or micas.  Phyllosilicates get their name from their tendency to form sheets (phyllon is the Greek for “leaf”).

Following occultations of stars in 1992 and 2008 it was decided that Egeria is fairly circular, measuring approximately 200 km in diameter.  It was also one of the seventeen lucky rocks chosen to take part in a University of Hawaii search for satellites and dust rings around asteroids, but none were found.

Egeria Mourns Numa (Claude Lorrain)

Egeria Mourns Numa (Claude Lorrain)

The eponymous nymph shown above was a minor Roman goddess whose origin is unclear (we don’t even know for certain if she was a water nymph or a mountain nymph).   Her cult is known to have been celebrated at several sacred groves, though not usually on her own.   She provided prophecy in return for gifts of water or milk, and was able to divine the sometimes seemingly impenetrable omens sent by the gods.  Her relationship with Numa Pompilius, the supposed second king of Rome (after Romulus) was as a sort of counselor.  Numa supposedly wrote down her teachings and had them buried with him.  When they were discovered by peasants years later, according to Livy, they were thought to be so inflammatory in nature that the Senate had them burned.


1875   ⇒   Discovery of asteroids 152 Atala by the French optician/astronomer brothers Paul and Prosper Prosper Henry, and 153 Hilda by Johann Palisa.


1885   ⇒   Birth, in Nashville, of Harlow Shapley, the American astronomer who correctly estimated the size of the Milky Way, and where the Sun sits within it.  This was achieved using RR Lyrae variable stars, a class of very handy “standard candles” whose luminosity can be used to estimate distances within our galaxy.


October 09 – Asteroid 109 Felicitas

Asteroid 109 Felicitas was discovered on October 9th 1869 by Christian Heinrich Freidrich Peters.  It’s in the main belt, fairly large at about 90 km wide, and dark.   It was named after the Roman goddess of luck, success, fertility, good fortune, and a host of related concepts.

Roman inscription: Lady Luck Lives Here.

Roman inscription: Lady Luck Lives Here.


On October 9th 1873 German physicist Karl Schwartzschild was born in Frankfurt.  He was the man who came up with the formula for the event horizon known as the Schwartzschild Radius, which defines the size of a black hole.  Very simply, it’s the size an object of a certain mass has to be so that nothing (not even light) can’t escape from its gravitational pull.  So anything smaller than its own Schwartzschild radius can’t be seen.  As an example, if the entire mass of the Earth were to be compressed into a sphere with a radius of nine millimetres, it would become a black hole.  The Sun, however, would only need to be compressed to about 2 miles.  So in this particular case, size would appear to be important.


August 9th, 1604, was a very important day for naked eye astronomy.  It was the last time that a supernova in our galaxy was definitely observed by the naked eye.  Kepler’s Supernova, as it is usually known, occurred in the constellation Ophiuchus, and was spotted by Johannes Kepler, who was in northern Italy at the time.   There have almost certainly been at least two subsequent supernovae in the Milky Way, but there are no records in existence to show that either was seen with the naked eye.


One launch to mention quickly: HETE 2, (High Energy Transient Explorer) launched today in 2000 from a Pacific atoll, to detect gamma ray bursts and perform an X-ray sky survey.


September 27 – 134 Sophrosyne / DAWN

Asteroid 134 Sophrosyne was discovered on September 27th 1873 by Robert Luther. Its a dark, C-type, main belt asteroid, with an estimated diameter, derived from occultation observations, of 110 km (68 miles).

Sophrosyne was one of the many spirits to escape from Pandora’s jar. As a goddess she represents a concept almost completely alien today in the westernised world, that of enlightenment and happiness achieved through harmonious living, restraint, patience and self-knowledge (rather than through the acquisiton of 4x4s and HD-TVs).

There are very few representations of today’s goddess floating around, and to be honest I could have shown you a shot of almost any classically dressed woman looking a bit thoughtful and passed her off as Sophrosyne, but I haven’t.


 ALSO TODAY . . . .

1814  —  Birth of American astronomer, Daniel Kirkwood, the man who noticed the gaps in the asteroid belt which now bear his name.  I look forward to receiving hits from Evertonians (another Dan Kirkwood was a player and director there).


2003  —  Launch of Kaistsat 4 (Korea Advanced Institute of Science and Technology SATellite), aka STSAT-1, with the primary mission of studying galactic hot plasma.


2003  —  Launch of SMART 1 (Small Missions for Advanced Research in Technology) by ESA.  SMART 1 was the first ESA to the Moon, and set a couple of unusual records.  It became the first mission to leave Earth orbit using just solar power, and the slowest ever to the Moon, taking 13 months.  It also holds the record for the lowest fuel consumption on an Earth to Moon journey.  As well as testing new power sources, SMART 1 did carry imaging equipment, and identified this location . . . .

Shackleton Crater viewed by SMART 1 (image credit: ESA)

Shackleton Crater viewed by SMART 1 (image credit: ESA)

. . . . as the best place to site solar panels for a future lunar base.


2007  —  Launch of DAWN, to rendezvous with Vesta and Ceres.  Vesta was visited in July 2011, resulting in this fabulous photograph, below.

Image of Vesta, by DAWN (image credit: NASA)

Image of Vesta, by DAWN (image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

Ceres was reached in March 2015, and DAWN is currently (September 2016) orbiting at a height of just over 900 miles, and has been busy sending back excitingly detailed shots like this one . . .

Ceres from DAWN (image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

Ceres from DAWN (image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

. . .  and this one:

Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/ID

Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/ID


June 20 – Georges Lemaître

The Belgian priest and astronomer luxuriating in the just-about-tweetable name of  Monseigneur Georges Henri Joseph Édouard Lemaître died on June 20th 1966.

A ripple of controversy surrounded our subject in 2011, when it was suggested that the Hubble constant should more properly be attributed to Lemaître, rather than the eponymous Edwin.  It had been said by some that Hubble, or someone in his circle, edited a paper by Lemaître in an inventive way, so as to make it less than obvious that Lemaître had got to the discovery of an expanding universe before Hubble.  It later turned out, however, that it was Lemaître himself who had omitted vital elements of the paper, possibly due to a linguistic misunderstanding.

Lemaître was an early pioneer of using Einstein’s equations to solve cosmological problems (Einstein himself wasn’t so sure they ought to be).  He was the first to estimate the Hubble constant, as already mentioned, and to  derive Hubble’s Law.   And just in case you thought that was enough, he was also the first person to propose a Big Bang type theory to describe the birth of the universe.

Monseigneur Lemaître

Monseigneur Lemaître

I won’t try to explain Hubble’s law here (because I probably can’t).  It can be expressed as a very simple equation to explain a very complicated situation, and if I start I might not be able to finish.  Let’s just settle for saying that the rate of movement of galaxies away from the Earth is proportional to their distance from the Earth and from each other, and it’s the Hubble constant that gives us the magic number that let’s us prove the proportionality.

Lemaître was extremely important for someone most of us have never heard of, and was honored all over the place while alive.  He was voted 61st in a survey of the 100 greatest Belgians in 2005.


May 29 – 72 Feronia

Yet another asteroid day.  Today we have 72 Feronia, discovered on May 29 1861 by the German-American astronomer Christian Heinrich Friedrich Peters, who went on to find another 47, so he must deserve a birthday shout-out on September 19.

Feronia is a large, dark main belt asteroid, about which there isn’t much to say except that it has a diameter of about 86km, a rotation period of a little more than 8 hours, and takes over 3 years to orbit the Sun.

Feronia’s namesake is a Roman goddess, variously associated with fertility, health and wildlife. She was apparently very popular among plebeians, and as I’m one myself I must remember to tweet her feast day on November 13.


1764  –  Discovery of globular cluster Messier 10 (by Charles Messier).


1889  –  Discovery of asteroid 284 Amalia  by Auguste Charlois.


May 28 – 99 Dike

Asteroid 99 Dike was the first of many asteroids (and the occasional comet) to be discovered by Alphonse Borrelly from his Marseilles observatory. This one was spotted on May 28th 1868.  I have very little to say about it, except that it should be pronounced die-kee rather than dyke or decay.

Dike was a daughter of Zeus and Themis, and was the goddess in charge of justice and fair judgement in the mortal world (her mother had the same responsibility over the immortals).


May 27 – 44 Nysa

Asteroid 44 Nysa is head of the Nysian family of main belt asteroids.  It is a type E asteroid, a group thought to have surfaces of the orthorhombic silicate enstatite, a name I remember well from my days spent hopelessly trying to remember mineral compositions for Mr Hughes’ A-Level Geology class.

Nysa was discovered on May 27th 1857 by our old friend Hermann Goldschmidt, and named not after a person or mythical creature, but a place.  Nysa was a mythological land, linked to Africa , Arabia, or more likely India, where Dionysus was raised by the Hyades.


May 22 – 41 Daphne

Asteroid 41 Daphne was discovered on May 22nd 1856 by Hermann Goldschmidt. It is a C-type, main belt asteroid, orbiting in 9:22 mean orbital resonance with Mars. It has a satellite, S/2008 (41) 1 which flies round it every 1.1 days.

Daphne was a nymph who attracted the eye (among other organs) 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.


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. 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.