New Years' Eve 2009: Lunar eclipse and a Blue Moon

One thing is for sure - the Full Moon will past through the shadow of the Earth on New Years' Eve. For about 30 minutes either side of 19:24GMT, the bottom right of the Moon will be dark-red in colour (looking similar to the photo below taken in 2006). The bottom-right of the moon will appear red due to sunlight passing through the Earth's atmosphere and hitting the Moon, and our atmosphere only allows red light to go straight through, which is also why sunsets are red.
Do take a look while you are preparing your New Year celebrations!

One thing that is not so sure - will the full Moon on the 31^st also be a "Blue Moon"?

For sure, the Moon will not be the colour blue. But as with the expressions "Turned the air blue" or "Feeling blue", blue does not always refer to colour. And there is more confusion, since there are several definitions of "Blue Moon" in the English language.

The modern definition (thought to originate from an article in a 1946 article in the Sky & Telescope magazine) states that if a month has two full moon's, the second one is called a "Blue Moon". This definition is popular today probably due to its simplicity.

The older (pre-war) definition is that a "Blue Moon" is the third full Moon in a season with four. This is because each full moon has a name. For example, the full Moon in April in English Medieval times was known as the Seed Moon. If there was a second full moon in March, the Seed Moon would come too early for seeding crops, and so a "Blue Moon" was inserted and the following full-moon was called the "Seed Moon". So a "Blue Moon" was inserted to keep the names of all the other full moons synchronised.

Do enjoy the Full Moon of New Year's Eve - and why not go for a Blue Moon Walk to see in the New Year?

Happy Solstice!

At 17:47 GMT today, it is officially winter!

That is the time when the poles of the Earth are aligned with the Sun, which is what we call the solstice. The North pole is now pointing away from the Sun (the Winter Solstice, and the shortest day), in the Southern hemisphere, the South pole is pointing towards the Sun (the Summer Solstice).

The image below shows a stacked series of images taken 20 minutes apart throughout the 17th December, 2005 (within just a couple of days of the winter solstice), showing how the Sun moved across the sky during that day, from the South-East to the South-West. A timelapse movie version is also available, showing how low the Sun is in the sky at this time of year.

There are lots of special events to mark the solstice, including a gathering at Stonehenge in Wiltshire (see these photographs: #1, #2, #3, #4). Under the early Julian Calendar, the winter solstice actually occurred on the 25th of December, but because that calendar was not accurate, the solstice slipped to the 21st (the accuracy of the calendar was corrected with the introduction of the Gregorian calendar in 1582).

However, we still traditionally keep the 25th of December as the day for celebration, and Christmas now includes a rich mix of celebrations, including Roman (Saturnalia, and Dies Natalis Solis Invicti, the birthday of the unconquered sun), Nordic Pagan festivals and the Christian celebration of the birth of Christ (see more about the origin of Christmas at this Wikipedia article).

Whichever way you choose to celebrate this time of year, I hope you will enjoy yourselves and have a very happy festive season!

Lakes on Titan

Telescopes on-board the Cassini spacecraft orbiting Saturn has seen Sun-light glinting off a lake on the moon Titan - amazing!

But they are not lakes of water. At -180°C, it's far too cold for that. These are lakes of liquid hydrocarbons, such as methane, on a part of the moon dotted with many lake-shaped basins. When the Huygen's probe landed on Titan in January 2005 it took the image to the left.

One has to wonder - could there be primitive life on Titan, or is it simply far too cold?

Last week's Active Sun

Although we are definitely at a solar minimum, that does not mean nothing is happening!

The sequence of images below, taken by the NASA/ESA SOHO Observatory, shows a small sun spot system moving over the last week, as the Sun itself rotates.

With a lot of imagination, you can half-believe that it looks a bit like a Christmas tree, too!

Merry Christmas everyone!

Geminids 2009

I know it was a week ago, but better late than never. This years Geminid meteor shower was spectacular, but the weather was so frustrating.

Heading off to my favourite dark site, just 20 minutes walk away and with a nice southernly view, I noticed that the cloud was following me. Should I give up before I'd even started observing? I stood and waited for maybe 15 minutes, until I saw a convincing gap in the clouds approaching. I looked in the opposite direction and saw a shooting star that convinced me to carry on and set up my camera.

Within seconds - there's a nice one. 15 seconds later - another. And then within a minute a trio heading from Gemini, low towards the left! The trio were not perfectly in sync, with milli-seconds between each, but they seemed to orignate from the same point. And then even more... I was amazed until, after just 10 minutes, thick cloud came in to end the day's play. How frustrating.

So, the Geminid shower remains my favourite, especially after seeing and astonishingly bright one back in 1994 (it so so bright it actually looked like a burning rock falling through the sky!).

It maybe cold at that time of year but with three pairs of trousers, and 5 layers on the top half, I was warm and was suitably rewarded.

Geminid meteor shower peaks

We are currently travelling through dust left behind by an asteroid called 3200 Phaethon, which we think is an extinct comet. As the Earth travels through space at an astonishing 70,000 mph, these bits of dust hit the atmosphere causing "shooting stars" as the dust burns up.

You can see these shooting stars throughout mid-December, but the main peak is from the 12th to the 14th of December where you could see up to two a minute under ideal conditions.

It is (unfortunately!) best to see shooting stars in the early morning, a few hours before sunrise, since that is when we are stood on the "front" of the Earth as it orbits around the Sun. It's a bit like driving through snow - it looks best looking forward where you see all the snow rushing towards you, and it's not so exciting when you look out of the back window.

XMM-Newton: 10 years old today!

The XMM-Newton space telescope is celebrating its 10th anniversary in space!

Although there is a huge amount of British involvement in XMM-Newton, it truly is an international mission. In brief...

• Two out of three X-ray camera's were built (and are maintained) in the UK (the EPIC-MOS camera's pictured above-left);
• The optical/UV telescope was built in the UK;
• One X-ray camera (the EPIC-PN) was built in Germany;
• Two spectrometers (the RGS) were built in the Netherlands and the USA;
• All three X-ray mirror modules were built in Italy;
• Data analysis software and data storage by the UK & USA;
• The spacecraft was assembled in the Netherlands;
• The radiation monitors were built in France;
• Continuous XMM-Newton support is based in Spain, with support from the UK, Germany, France, Italy, Netherlands, and the USA;

XMM-Newton has made some amazing discoveries about the high-energy Universe in that decade. Lots of images from those XMM-Newton discoveries can be found online at the XMM-Newton image gallery, and a slideshow is available on the BBC News online website, narrated by myself (Dr Darren Baskill) and my colleague Dr Kathy Romer here at the University of Sussex's Department of Physics & Astronomy.

The EPIC-MOS cameras were built in the UK by a team led by Martin Turner, who had helped plan and build XMM-Newton over more than 25 years, until his death 6 months ago. The last time I spoke to him, we were discussing how to celebrate XMM-Newton's 10th birthday. All our celebrations of the great success of XMM-Newton are done in the memory of Martin.

December's Night Sky

This is the month to take advantage of, and enjoy, the long nights!

The earliest sunset here in southern England occurs at 15:54 on the 12th of December, and the shortest day is on the 21^st this year. The Earth is tilted, and the shortest day occurs when that side of the Earth is tilted directly away from the Sun - and so the solstice actually occurs at a specific moment in time, at 17:46 on the 21^st December, 2009.

The increasingly inaccurately named summer-triangle is still visible, low in the west, but only until 7.30pm - ideal for after-school observing events! And the Andromeda galaxy is still well placed in the evening sky (see last months posting for full details about both of those).

Jupiter is still a wonderful sight until about 8pm throughout the month - just look for the brightest object you can find, low in the west, and that will be Jupiter! Look through binoculars or a small telescope to see four of the 60 moons that orbit this gas giant.

The 21^st of December is a great day for a photo' opportunity. That late afternoon and early evening, the planet Jupiter is visible just below the Moon. And just to the top-right of Jupiter, is the planet Neptune - although you will need a telescope to see Neptune, as it is 10,000 times fainter than Jupiter!

Rising at 8pm in the east is the constellation of Orion - a very familiar sight in the winter skies, thanks to the three stars that form a straight line, and which are known as Orion's belt (as in the photo to the left). Just below those three stars in a line, are another group of three stars in a line... only, the middle star is not a star at all, but a huge gas cloud where stars are in the process of forming. You can see it with your own eyes, but look through a telescope and you can see much more detail, and take a long exposure photo', and you can see even more detail! The movie below shows the difference between looking through a telescope yourself, and taking a 15 minute long exposure photograph.

You can get some very easy-to-use and clear star maps from either Skymaps.com, or by using the excellent (and free) Stellarium Planetarium software.