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Astronomy Know How
Helping you See the Night Sky - Newsletter No. 38 December 2009
In this issue:
  1. December's Highlights
  2. Geminid Meteors
  3. Partial Eclipse of the Moon
  4. Star Clusters of Early Winter
  5. Other Deep Sky Delights in December
  6. News Links
  7. Become a confident Astronomer
  8. Are you interested in Imaging?
  9. Contact Us
December's Highlights

December brings thought of a well earned holiday and maybe the possibility of a new telescopes for Christmas! If you are looking for a present for an astronomer then you might like to look at my recommended books here if you live in the UK or here for the USA. It also brings us hopefully some clear dark skies to enjoy...

If you are interested in meteors, then you will hopefully have a treat coming this month in the form of the Geminids. But more of this presently...

Mars is now moving back into a good position for viewing and by the end of the month will be well placed to give us some great views. As the weeks go by it will appear to increase in size which will help us to see more features and markings on the red planet. It will mean staying up late or getting up early as will be well placed around 3:00am by the end of the month, but it will also be rising early as the weeks go by.

Jupiter is still visible in the early evening sky, but is now rapidly sinking into the south west, so take this opportunity to have a last look at this fabulous planet and its belts and moons, before it disappears into the murk. Observers with a telescope who live in North America will have an extra treat on the 2nd as at 6:08PST can witness Jupiter's moon Io passing in front of its other moon Europa. Just after dark, watch as Io approaches: Europa dims as it is covered, and Io reappears.

The beginning of December gives us the chance to view Mercury in the evening sky. You can find it close to the south western horizon for the first two weeks of the month at magnitude -0.5, so reasonably bright. It will then start to fade towards the end of the month. The easiest way to spot it, is by sweeping the region of sky where the Sun went down and please don't attempt this until the Sun has completely set, with binoculars. You will need a very clear horizon however and by that I mean not just clear of houses and trees, but also clear of the low cloud and murk that often appears low down around sunset. That of course, is one of the reasons why Mercury can be hard to spot!

Finally, the Moon will occult the star Wasat in the constellation of Gemini. This is also known as Delta Geminorum and you can find it low down in the east on the night of 4th December at around 20:50GMT when the Moon will seem to slowly cover the star as it moves gently from west to east. The leading bright edge of the Moon will begin the process and the star should reappear from the other (unilluminated) side of the Moon at around 21:48GMT.
Geminid Meteors

This month all the indicators are that we will have a good show of the Geminid Meteors, which will peak on the night of the 13th.

The Moon will not interfere and drown out any fainter meteors in the display and the radiant point, that is the point in the sky where the meteor shower seems to emanate from, will be almost directly overhead. The higher the radiant is in the sky, the more meteors that you are likely to see. Give yourself at least half an hour under the sky to improve your chances of seeing some of these lovely shooting stars.

Providing that we have clear skies, you are likely to see some of this this shower pretty much where ever you look. However, if you concentrate you gaze in the region of the constellation of Taurus, you may be increasing your chances. This particular shower tends to be quite photgenic inasmuch as they tend to be bright and slow moving and therefore easy to record photographically than say the Leonids that are fast moving and faint. The ZHR or Zenithal Hourly Rate, that is the expected rate of this shower under perfect conditions and with the radiant directly overhead is 100. Compare this the famed Perseid meteors that have a ZHR of 80!
Partial Eclipse of the Moon

New Year's Eve 2009 will be marked by, among other things, a partial eclipse of the Moon.

This is where a part of the Moon slips into the Earth's shadow. Although this won't be a particularly noticeable event, it is still worth looking out for as it will happen before the parties will really get underway and will be a conversation piece if you should need one.

The first umbral contact, that is where the Earth's dark shadow first touches the face of the Moon, will occur at 18:52GMT and mid-eclipse is at 19:23GMT. You should be able to make out the shadow of Earth encroaching on the southern part of the Moon quite clearly, although it may have a slightly reddish hue rather than black as you might expect, due to some of the sunlight being bent through our Earth's atmosphere. The eclipse will end at 19:54GMT when the Moon slips out of the shadow of our Earth. Well timed to allow you to get to your party!

Star Clusters of Early Winter

Last month I mentioned the beautiful star clusters of Taurus, namely the Hyades and Pleiades, but there are many more that you can enjoy as the winter approaches. Here I'll mention just a few more...

East of Taurus and north-east of the constellation of Orion you can find the constellation of Gemini the twins, which will play host to the radiant of the Geminid meteors that I discussed earlier. Gemini is also home to a lovely star cluster known as M35. This cluster shows up well in binoculars and small telescopes and you can find it by drawing an imaginary line up through the lower left ahnd star of Orion, known as Saiph, through Betelgeuse at the top left of Orion and on up for about the same distance as between these two stars.

Another lovely target for your binoculars or telescope is the cluster M34. You can find this in Perseus a little west of the star Algol. This cluster consists of around 400 stars and lies about 1500 light years away.

If you are willing to stay up late, around midnight at the beginning of the month, you can find the 'Beehive' cluster rising well in the east. This group of stars is designated M44, otherwise known as Presepae and it is just visible with the naked eye from a dark sky site in the constellation of Cancer the Crab, eastward of Gemini the Twins.

Finally, take a look M103 in Cassiopeia. You can find this just to the east of delta Cassiopeia the lower left star in the 'w' of the constellation. It will show up nicely in binoculars or a small telescope. It is not a big cluster, but is marked by a destinctive red giant star in the middle of the group. It is approximately 9000 light years away.
Other Deep Sky Delights in December

There are lots of interesting nebulae to be viewed at this time of year using binoculars and telescopes.

The great Orion Nebula is almost unavoidable at this time of year as the constellation swings into view.

M42 or the Great Orion Nebula is a magnet for most observers, but don't miss out on its smaller interesting companion M43 just to the north of M42. If you have an H-Beta filter you can also get a view of the famous 'Horse Head' nebula just below the left hand star in the belt of Orion called Alnitak. This is a dark nebula and is difficult to see without a filter.

If you also possess a UHC or Nebula filter, see if you can detect the Rosette Nebula. This can be found in the constellation of Monoceros the Unicorn, an inconspicous constellation to the east of Orion. You will need a low power wide angle eyepiece to hunt down this region of glowing hydrogen gas, which is also quite faint but nevertheless covers quite a large area of sky, around three times the diameter of the full Moon! There is a star cluster in the middle of the nebula NGC2244, the stars of which have been born from the gas and dust that makes up the Rosette nebula.

Finally, in this Yuletide, I have to mention the 'Cone Nebula' which forms part of the nebulostiy surrounding the 'Christmas Tree' cluster. You can find it just north of the mid-point between the stars Betelguese in Orion and Procyon in Canis minor. Again, you'll need a filter to detect the nebula easily, but the cluster should show up well even in binoculars. Happy hunting!
  Here are some links to some other recent news stories that I thought you would find interesting...

Chinese Academy of Science will join project to build giant telescope
The Chinese Academy of Science has decided to join a partnership of research institutions, including Caltech, that have teamed up for the Thirty Meter Telescope Project.

Less can be more when it comes to street lighting claims report
Light pollution not only blocks out the night sky but encourages crime and damages the environment, a Royal Commission report claims. more...

Pacificís ancient astronomers celebrated at Mata Ora
Ancient Polynesian astronomers and navigators explored and settled the Pacific a millennium ago using indigenous scientific knowledge and the night sky as their guide. more...

Italy collector finds Galileo's lost tooth, fingers
An art collector has found a tooth, thumb and finger of the renowned Italian scientist Galileo Galilei who died in the 17th century, Florence's History of Science museum announced on Friday. more...

The Last Meal of Centaurus A
It currently devours a small galaxy more...

Herschel telescope 'fingerprints' colossal star
The death throes of one of the biggest stars known to science have been spied by Europe's Herschel space telescope. more...

  Do you want to learn more about the night sky and how to use telescopes and binoculars to see it better?..

My online course gives you all the essential information to be a good astronomer, without lots of jargon or difficult maths. You'll get loads of free bonuses and it also has videos and animations to help make the explanations clear and concise. So if you want to know what Sir Patrick wished for...

...please take a look at my eCourse called
'Basic Astronomy with a Telescope'. It's what Sir Patrick wished he'd had when he started out in astronomy!

  Are you interested in Imaging?

You can learn how to take stunning images of the night sky with your digital slr camera that will amaze your friends and family with the eBook
DSLR Astrophotography - A Beginners Guide which I co-wrote with my friend Jon Walton...

To contact us

Telephone me on +44(0)208 144 1091

or contact me by email

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