Enigmatic Europa

Discovered in 1610 by Galileo, Europa is the smallest of the four 'Galilean Moons' of Jupiter. Through a small telescope its easy to spot as the second one out from the planet. It is named after a Phoenician noblewoman in Greek mythology, Europa, who was courted by Zeus, the father of Gods, and became the queen of Crete. Europa is slightly smaller than our own moon and orbits Jupiter in just over three and-a-half days. Its density suggests that it is similar in composition to the terrestrial planets, such as Earth and Mars, and is mainly composed of silicate rock. It has long been thought that Europa has an outer layer of water around 60 miles thick, some of this frozen as an ice upper crust, some as a liquid ocean underneath that ice. Europa has also featured high in science fiction, most notably in Arthur C Clarke's '2001' where it was home to a primitive life form, seeded there by aliens and set into evolutionary overdrive when Jupiter is transformed into the Star Lucifer.

It was long thought that it would be difficult for any water to travel up though Europa's thick icy crust, but researchers at the The University of Texas found the best evidence yet for water just beneath the surface of Europa. An analysis of the surface suggests that plumes of warmer water well up beneath the icy shell, melting and fracturing the outer layers. They also suggest that small lakes exist just a couple of miles below the crust.

The researchers studied the surface of Europa trying to work out what formed its scarred and fractured surface. They suggest say up-welling of warmer water causes melting of surface ice, forming cracks. Freezing water then flows in the cracks and so you get existing ice cemented in with new ice. The underside then freezes again, which causes more uplifting. These shallow lakes mean that surface waters are probably vigorously mixing with deeper water. It is also possible that icy eddies could transfer nutrients between the surface water and the deeper ocean below. All this is another boost to those who think Europa is a place which may well harbor life.

Finding Comet Ison

Comet ISON is becoming more and more visible to the amateur astronomer this month. From the UK though it means an early start as it doesn't rise until around 0230 (this weekend). On the plus side however, given clear skies it is easy to locate, if not actually spot, as we have a couple of celestial pointers. Around 0400 it should be high enough to be out of the 'murk'. Look for the constellation of Leo, The Lion, and find Regulus, the bright reddish star to the bottom right. Mars should be visible below and to the left, shining at around magnitude 1.7. Follow a line down to the left, about a third of the distance again between Regulus and Mars, and ISON should be there, Visible in a scope of around 6" diameter. If you do astrophotography the best way to image it would be through a shortish image at a high ISO. say 30 seconds at ISO 1600. Remember though, if you scope is tracking normally, the stars will come out sharp, but ISON may be blurred. That is because the comet is itself moving against the background of stars. The image above shows where ISON can be found in the early hours of Monday 21st October, from the North of the UK.

Penumbral Lunar Eclipse 18-19 October 2013

Tonight there is a Penumbral Lunar Eclipse. This type of eclipse occurs when the Moon passes through the Earth’s penumbra, that is the outer shadow (seen above). The penumbra causes a subtle darkening of the Moon's surface as viewed here on Earth. At no time during this eclipse does the Moon pass through the inner shadow, the Umbra. The amount of darkening depends on a number of conditions and is very hard to predict.

The eclipse itself will be visible across all of Europe and Africa and over Eastern parts of North and South America. For those of us in Europe this will be the last lunar eclipse visible until the Total Lunar Eclipse of 28 September 2015.

UK Light Polution

Ever wondered how bad light pollution (LP) is in the UK? Well this image shows it well. It's an interesting view, across Scotland the Central belt with Edinburgh and Glasgow, are clearly visible, as are Inverness and Aberdeen, but we still have some dark sites. Head North from the Central belt and you don't have to go too far to find some dark skies. Head South too and around the borders the skies are reasonably non-polluted. Also obvious are some of the Islands around Scotland, there are plenty of dark sites there. For more info check out this site.

For a really dark site, head to the dedicated Dark Sky Park in Galloway Forest. It was established as the first Dark Sky park in the UK.

Seventh Planet - and how to see it

If you have never seen the Seventh planet, now is a really good time to try and spot it. It is visible now most of the night in the constellation of Pisces and is easily found with just a pair of binoculars. Uranus, the seventh planet from the Sun, is the third largest and the fourth heaviest in the Solar System. In classical mythology it is named after the father of Saturn and the grandfather of Jupiter. Uranus is actually just visible to the naked eye, given good seeing conditions, but it was never recognized as a planet by ancient observers because it is not very bright and it has a very slow orbit. It was in fact spotted a number of times by some famous astronomers, including English astronomer John Flamsteed almost a hundred years earlier but was always thought of as a star.

Now, as an aside, Uranus is often simply refered to as the 'Seventh Planet' simply because it stops all those "Have you ever seen Uranus?" jokes. Funny the first time you hear it, but after a few hundred times it gets a bit tiresome...

Its formal discovery was credited to Sir William Herschel in 1781 from the garden of his house in Bath. This discovery expanded the known boundaries of the Solar System for the first time in history. Uranus was also the first planet to be discovered with a telescope. A gas giant, it takes 84 years to go around the Sun at an average distance of some 3 billion kilometres. Bizarrely it is tilted by almost 90 degrees onto its side, the result of some ancient event, probably a collision early on in the formation of the solar system. It has a faint ring system, first spotted possibly by Herschel himself and confirmed during the fly-by of the probe Voyager 2. Uranus has 27 known moons in total, 5 of these are the large 'main' moons, but the Uranian satellite system is the least massive of all the gas giants.

If you get clear skies in the next few days, now is a good time. Given dark skies, good seeing and good eyesight it is just possible to spot it with the naked eye, but you need to know where to look. The best way to do it is with a pair of binoculars. Consult a start chart or an astronomical website.

On the 17th of this month is is near the Moon so remember it's position and look on a night when the Moon has moved on. The image below shows it's location as seen from central Scotland. If you do spot her, remember you are probably in the one percent of humanity who has ever seen the seventh planet with their own eyes.

Seven Sisters

As an amateur astronomer I am fascinated by the night sky, but I am equally fascinated by the mythology and legends the ancients attached to the heavens. Most of the bright celestial object have interesting histories surrounding them and at this time of year, one of my favourite surrounds one of the most beautiful winter sky objects, the Pleiades. M45, to give it's official designation, is an open star cluster containing a collection of middle aged stars. It is located in the constellation of Taurus, easily visible at this time in the winter sky. It is one of the nearest star clusters to us and is the cluster most obvious to the naked eye in the night sky. It has been easily visible throughout humanity.

To the ancient Polynesians, all the stars were put there by the God Tane, the god of the forests and the birds. He did so to light the sky up at night, so his father, the sky father, could be better seen in all his finery. However he grew jealous of one particularly bright and beautiful star so he broke it up into several pieces and cast it back into the sky. That star became the Pleiades. The Babylonian's named them “MUL MUL” or "star of stars” and some Greek astronomers thought them to be a distinct constellation in their own right. They are mentioned by Homer in both the Iliad and the Odyssey, hence another name, the “sailing stars”, used by Greek sailors to navigate. The bible mentions them three times and they are also mentioned in both Hindu script and the Koran. The Vikings thought they were a Hen with her chicks and the Lakota tribe of Native Americans had a similar view. To them they were a woman giving birth. Indian astronomers called them the “Six Mothers” but they are best known today as the “Seven Sisters”, after the name given to them by the ancient Greeks to represent the daughters of Atlas and Pleione. The count often depends upon your viewing conditions and your eyesight. Throughout history they have often been used as a test of eyesight. You could not join Napoleons army unless you could see six or seven. The Pleiades is easily visible now in the night sky from here in the UK. It rises early and by midnight is nice and high in the night sky.

Ten of the brightest stars are named but the cluster contains actually over 1000. Interesting the nearest figure given to the actual count comes in at 100. This was the count mentioned once in the bible and also in Ukrainian folklore. Modern science estimates their age at around 75-100 million years old. The cluster's relative motion will eventually lead it moving through our sky, eventually passing below the feet of Orion. Like most open clusters, the Pleiades will not stay gravitationally bound forever, it cannot. Some component stars will be ejected after close encounters with others and some will be thrown out by gravitational tides. Calculations suggest that the cluster will take about 250 million years to disperse, so we still have plenty of time to enjoy it, and maybe make a few more myths.

Capturing Andromeda

M31, The Andromeda Galaxy is a real challenge to image. It's bright and easy to see, even with the naked eye, but this brings it's own challenges. As a photographic target it's difficult because the centre is very bright but the outer edges show some very subtle detail which is on visible with long exposures. To image it is a real challenge.

I am not really a DSO photographer but have been wanting to get into this area of Astrophotography for a while. I usually prefer to shoot the Moon and Planets. The challenge is my scope (a SW200P) is a bit of an all rounder, my DSLR's are Nikon's (yes, I prefer Nikon's not Canon's - sacrilege amongst most Astrophotographer's I know) and I don't have a guided scope, I use a simple dual axis drive which means getting a decent Polar alignment, often harder than you would think. Anyway, I thought it was time to give it a go.

This week we had two clear nights in a row, unheard of for the West coast of Scotland, so I set up in my garden both nights. To counter my lack of guiding I decided to take 30 second exposures, the downside means lot's of separate images. Roughly translated that means lot's of time sitting in a chair next to the scope clicking the remote. After shooting darks and lights I must have had around 400 photos to process, with about an hour and a half of actual 'lights' or image data.

Next comes the processing. To be honest, imaging is the easy part in some respects as processing is more an art than a science. I used Deep Sky Stacker to align and stack my images and then I use Gimp to process. This image of M31 took me hours and hours, often going back and starting again... very frustrating! After a  long time I settled on a final image and this is the one shown below. Its not quite as sharp as I would like but it shows some nice dust lanes in the outer edges of the Galaxy. For a first proper go at a DSO I am quite pleased with it. Hopefully my technique will improve over time.