Friday, 30 September 2016

Astrognome Scrapbook Themisto


Themisto also known as Jupiter XVIII is a small irregular satellite of Jupiter was discovered on September 30th 1975, the subsequently lost, and rediscovered in 2000.

Themisto seen moving against starry background

Themisto was first discovered by Charles T. Kowal and Elizabeth Roemer, however, not enough observations were made to establish an orbit and it was subsequently lost. Then, in 2000, a seemingly new satellite was discovered it was soon confirmed that this was the same as the one observed in 1975.

Themisto only has a radius of about 4 kilometres and takes around 129 days to orbit Jupiter.

Wednesday, 28 September 2016

Astrognome Scrapbook Ananke


A small irregular shaped moon of Jupiter discovered on Wednesday 28th 1951 by Seth Nicholson at Mount Wilson observatory in America. Ananke moves in a retrograde or in the wrong direction compared to most of the other moons that orbit Jupiter.

Although discovered in 1951 Ananke did not receive its present name until 1975, before then it was simply known as Jupiter XII. The radius of Ananke is about 14 kilometres and takes around 610 day to orbit Jupiter.

Tuesday, 27 September 2016

The Astronomy Show

The Astronomy Show

On Drystone Radio this Wednesday on The Astronomy Show there will be news of the dramactic results coming back from Europa of water geysers being seen by the Hubble Space Telescope.

The A-Z of constellations continues with Auriga the Charioteer one of the really great constellations.  After last week’s power cut we will try again to highlight M6 in Serpens with The Messier Marathon, and the list of bright stars continues this week with Procyon.

 This plus the astronomical scrapbook, the latest astronomy news, together with what can be seen in the night sky this week plus the astronomical society news.

The Astronomy Show, every Wednesday between 3 pm and 5 pm with Martin Lunn on Drystone Radio 103. 5 FM listen on line at  or hear me via podcast.  You can contact me at Drystone radio on

If you missed the Astronomy show on Wednesday 28th September it is available on podcast for 30 days.

Go to and check the podcasts.  

Astrognome Scrapbook Daniel Kirkwood

Daniel Kirkwood 

Daniel Kirkwood was born in Harford County, on September 27th 1814 Maryland, USA.  He graduated in mathematics from the York County Academy in York, Pennsylvania in 1838.

Kirkwood's most significant contribution to science and mathematics came from his study of asteroid orbits. When arranging the then-growing number of discovered asteroids by their distance from the Sun, he noted several gaps, now named Kirkwood gaps in his honour, and associated these gaps with how Jupiter affected the asteroids. Kirkwood also suggested a similar affect was responsible for Cassini Division in Saturn's rings, as the result of one of Saturn's moons.

He was the first to correctly suggest that the material in meteor showers is cometary debris.

Daniel Kirkwood died on June 11th 1895

Monday, 26 September 2016

Astrognome Scrapbook A real Blue Moon

A real Blue Moon

On the 26th September 1950 a blue moon was sighted over the Scotland and the north of England. It was the night of an eclipse of the Moon. A lunar eclipse occurs when the Moon passes into the shadow of the Earth and then usually appears to turn a coppery red colour. This is caused by the light passing through the Earth’s atmosphere before reaching the Moon. It is then bent or refracted and most of the light reaching the Moon is at the red end of the spectrum rather than all the normal white light made up of all the colours of the spectrum.

It was a very strange sight that was caused by an enormous and devastating wild fire in Canada. Smoke from the forest fires crossed the continent and across the Atlantic, it then reached Great Britain. The ash that was caused by the fires affected the light and caused it to be bent again towards the blue end of the spectrum causing the Moon to appear blue.

This was dramatically highlighted in 1991 when the volcano Mount Pinatubo in the Philippines erupted sending massive amounts of ash into the upper parts of the atmosphere. The Moon went a very dark inky blue colour.

A blue moon has become shorthand for an extremely rare event. The Moon turning blue that night caused a certain amount of panic and concern, there were rumours that this was some form of retribution descending over the universe for our atomic meddling’s, or worse, the first sign that the Earth was about to do something eccentric like freezing solid or blowing up.

Today the term blue moon is used to describe the second full moon in a calendar month. 

Astrognome Scrapbook R Scutum

R Scutum

R Scutum was discovered on September 25th 1795 by Edward Pigott one of the fathers of variable star astronomy while he was living in the city of Bath in England. At the time of the discovery of R Scutum there were few variables stars known. Variable stars are that very in brightness over a period of time.

R Scutum is a giant star that varies between magnitude 4.2 and 8.6 over a period of around 140 days. Its spectral class changes from G to K. It is the brightest of the RV Tauri type stars (These variables are very luminous stars and are typically given a supergiant spectral luminosity class. However they are relatively low mass objects, not young massive stars. They are thought to be stars that started out similar to the sun but evolved differently).

When at its brightest it is visible to the naked eye, but at its dimmest you will need good binoculars or a small telescope to locate it. In the sky it is about 1 degree or 1 finger width northwest of the Wild Duck Cluster (Messier 11).

Friday, 23 September 2016

Astrognome Scrapbook Mars Climate Explorer

Mars Climate Explorer

On 23rd September 1999 NASA lost the $125 million spacecraft Mars Climate Explorer, as it reached Mars.

Unfortunately one engineering team used metric units while another used English units for a key spacecraft operation, for that reason, information failed to transfer between the Mars Climate Orbiter spacecraft team at Lockheed Martin in Colorado and the mission navigation team in California.

"People sometimes make errors," said Edward Weiler, NASA's Associate Administrator for Space Science in a written statement. "The problem here was not the error, it was the failure of NASA's systems engineering, and the checks and balances in our processes to detect the error. That's why we lost the spacecraft."

The navigation mishap pushed the spacecraft dangerously close to the planet's atmosphere where it presumably burned and broke into pieces, killing the mission on a day when engineers had expected to celebrate the craft's entry into Mars' orbit.

The space craft had completed a nearly 10 month journey when it reached Mars, its mission was to relay data from an upcoming mission called Mars Polar Lander, and help understand the early climate on Mars.