Full Moon Experiment

If your skies are clear tonight, January 29, take advantage of one of the sky watching highlights of the year. A full Moon and Mars will be putting on a show, and the pair will be prominently close to each other in the sky. Plus, this Friday night's full Moon is the biggest and brightest full Moon of the year. It's a "perigee Moon," as much as 14% wider and 30% brighter than other full Moons you'll see later in 2010.

If you have a camera try taking a photo of this full moon and then the next couple of full moons (you’ll need to make sure you keep the camera “settings” the same each time); you should be able to see the difference in the “apparent” diameters .

For more information take a look here: www.universetoday.com/2010/01/28/

Image credit: Universe today - McDonald Observatory

The Moon's Seas

A couple of days either side of the full moon is a good opportunity to try and take a look at all the moon’s seas or lunar maria. What you are looking at are, of course, not seas in the conventional sense of the word, they are in fact large, dark, basaltic plains. The plains are less reflective than the mountains or "highlands" as a result of their iron-rich compositions, and hence appear dark (and sea-like) to the naked eye.

With a pair of binoculars you should be able to see eleven Seas and one Ocean; you may also be able to spot a couple of the larger craters such as Tycho or Copernicus. Bon voyage!

Photo credit: Wikipedia

Star Bright

In a previous posting we looked at the fact that not all stars are the same colour, this time we’ll take a look at their brightness. You will have noticed (I hope) that when looking at Orion, not all the stars are of the same brightness. Betelgeuse (top left) and Rigel (bottom right) are much brighter than the stars top right and bottom left which are in turn brighter than the three stars that make up the “belt”!

So, why are some brighter than others? Are they closer? Are they Bigger? Are they hotter? Are they all three? Take some time to think about it (and maybe look at some other stars) and we’ll talk about it in the next posting.

Image credit: Wikipedia - Mouser Williams

Seeing Double – the “Wow Factor”

If you managed to find the two double stars we talked about in an earlier post, here are a couple of double stars a little more difficult to locate, but with some “wow” factor.

Among the best of all double stars and relatively easy to find is the last star of the string of bright stars that helps make the constellation of Andromeda. The second magnitude star, Gamma (γ)Andromeda (Almach), is stunning through a telescope, even a small instrument showing a superb pair separated by a good 10 seconds of arc.

Another relatively easy to find is Eta Cassiopeia, this double has a nice contrast with stars having yellow and orange colours.


If you would like to learn more about double stars, take a look here: http://en.wikipedia.org/wiki/Double_star/wiki/Double_star

The moon – proper motion and apparent motion.

If you have been following the moon this week you should have noticed some interesting things, firstly it has “grown” from a very small crescent to a now “half moon”. Hopefully you will have also noticed that at the same time each night the moon was “higher” and further to the west (to your left when looking towards the moon), you may also have spotted that the moon was not in the same position with regards to the background stars – earlier this week the moon was not too far from a very bright star low on the horizon (the bright star was, and still is, in fact Jupiter) and now it’s a long way from Jupiter and much higher in the sky.

So, what’s been happening? As you know, the moon orbits around the earth (i.e. it has “proper” motion), corresponding to a movement relative to the background stars by an amount roughly equal to its own diameter each hour; this movement is from west to east i.e. the moon starts (as a new moon) low in the western sky and moves slowly “upwards” and eastwards. At the same time, due to the fact that the earth is turning on it’s own axis from west to east, the stars and the moon (and of course the sun) appear to move from east to west. It’s a bit like someone “walking up the down escalator” assuming the person is walking upwards slower than the escalator is going down, he or she will eventually arrive at the bottom of the escalator.

If you would like to know more about the motion of the moon, take a look here: http://en.wikipedia.org/wiki/Orbit_of_the_Moon


If you have a pair of binoculars you can take a look at some of the moons “seas”, you should be able to see (1) Sea of Crisis, (2) Sea of Fertility, (3) Sea of Nectar, (4) Sea of Tranquillity, (5) Sea of Serenity and (6) Sea of Cold.

Photo credit: The Universe Today

Seeing Double

Find the constellation of The Plough (also known as the Big Dipper, the Saucepan or the Wagon depending on which country you are in) and take a look at the second star of the “handle” of the saucepan; you should be able to make out a second, fainter, “companion” star. The two stars are sometimes called the "Horse and Rider," in fact the ability to resolve the two stars with the naked eye is often quoted as a test of eyesight.

Many of the stars in the sky are in fact double stars (or even triple or quadruple stars), although not as easy to see as the example above. Many, however, can be seen in a small telescope or even in a pair of binoculars.

What is particularly interesting (and often quite spectacular) is the fact that many of the double stars are often two different colours, yellow and green, or orange and blue for example.

Here are a couple of double stars relatively easy to find.

The Pole star (Polaris) is a very easy double and can be seen in any small instrument
Rigel the bright star bottom right in the constellation of Orion is also easy

In another post we’ll look at some double stars a little more difficult to find, but when you find them or show them to others you will undoubtedly here “wow”!

Photo credit: Wikipedia

Watching the Moon

This is an excellent week to follow the moon as it travels across the sky, if you take a look at its shape and position over a number of nights (to the end of the week for example), you should notice some interesting changes. Here's what you need to do:

Take a look at the moon at the same time each evening (between 8pm and 9pm would be good) and note the following:

• The shape or form of the moon
• The position of the moon in the sky (high, low, above a tree or a building, etc)
• The position of the moon with regards to nearby stars (to the left/right of a bright star, between two bright stars, etc.

When you've done that over a week you should be able to distinguish between the "apparent" motion of the moon and the "proper" motion of the moon, but we'll discuss that at the end of the week.

Photo credit: Bob Larcher (photo taken with a digital camera "hand-held" in front of the eye piece of an 8 inch reflector

Star colours

Did you get to take a look at the stars? Here's what you should have seen, Betelgeuse (top left of Orion) is a reddish star, Rigel (bottom right of Orion) is a bluish star, Aldeberan (found by the following the imaginary line through the "belt" upwards to the right) has a distinct orange tint to it and Sirius (found by the following the imaginary line through the "belt" downwards to the left) is white - yes there are white stars! There are also yellow stars, green stars and stars of almost all the colours of the rainbow!

So why are stars different colours? In short it's linked to their temperature, blue and white stars being extremely hot and red and orange being somewhat cooler, although still very hot!

If you would like to know more about the colours, temperatures and sizes of stars, take a look here: http://en.wikipedia.org/wiki/Star

What colour are stars?

If you asked someone what colour stars are, they would probably say white, and they wouldn't be wrong; however, not all stars are white.

Go and take a look at the stars we have been talking about in previous postings; Betelgeuse (top left of Orion), Rigel (bottom right of Orion), Aldeberan (found by the following the imaginary line through the "belt" upwards to the right) and Sirius (found by the following the imaginary line through the "belt" downwards to the left).

Take a good careful look at these stars and in the next posting we'll talk about theirs colours!

Orion - a signpost in the sky

Orion is an excellent constellation to use as a starting point to find some interesting objects in the sky. Draw an imaginary line through the three stars that make up the belt; now follow this line downwards (bottom left) and you should come to an extremely bright star – in fact it’s the brightest star in the sky and it’s name is Sirius or “the dog star”, it is in the constellation of The Great Hunting Dog. Not only is Sirius very bright, but it is also one of our closest stars.

If you follow your imaginary line upwards (top right) you will come across another very bright star, this time it’s Aldeberan in the constellation of Taurus, the Bull. If you continue the imaginary line you will come across what looks like at first a small cloud, if you look carefully you should be able to see six (or if you have a really dark sky) seven stars, this is an open star cluster called the Pleiades or the Seven Sisters – with a pair of binoculars you should be able to see 20 or so stars.

Another imaginary line left (eastwards) across the two shoulder stars indicates the direction of Procyon in the Small Hunting Dog, and a final line from Rigel through Betelgeuse points to Castor and Pollux the two main stars of the constellation of Gemini or the Twins.

You should now be able to find 7 of the brightest stars in the sky and one of the most impressive open star clusters.

Have fun!

Image credit: Wikipedia

Orion

This is a great time of the year to see one of the largest and most spectacular constellations in the sky – Orion, the hunter. It is extremely easy to locate, simply go outside at about 9 pm, face south, look up to about 45° degrees above the horizon and there it is! The first thing that should strike you is the three bright stars in a row from “bottom left to top right”, this is the hunter’s belt and is in the middle of the constellation; surrounding the belt at roughly similar distances are four bright stars, which are considered to represent the outline of the hunter's body, and, descending from the 'belt' is a smaller line of three stars (the middle of which is in fact not a star but the Orion Nebula), known as the hunter's 'sword'.

If you have a pair of binoculars, take a look at the sword and you should be able to see the “hazy” form of the Orion nebula – an area where new stars are being formed!

Orion contains two of the brightest stars in the sky, above and to the left of the belt you will find a reddish star called Betelgeuse and below and to the right of the belt you will find a bluish star called Rigel.

In the next posting we’ll see how Orion can be used to find some other interesting objects in the sky.

If you would like to learn more about Orion, take a look here: http://en.wikipedia.org/wiki/Orion_(constellation)

Close approach of the moon to Antares

If you are up before the sun on the morning of 11 January, take a look eastwards and you'll see the moon very close to Antares the brightest star in the constellation of the Scorpion. If you have a pair of binoculars you may also be able to see M4 an open star cluster.

For more information about M4, take a look here: www.seds.org/messier/m/m004.html

From the Big Dipper to the Southern Cross

If you cannot get out to observe because of bad weather don't forget the second session of the project "From the Big Dipper to the Southern Cross" on the 10th of January, the project intends to bring the two hemispheres together - truly One People, One Sky! For this project there will be two telescopes - one in the northern hemisphere and one in the south - on two different nights. No experience is needed. This is a chance to watch as an experienced telescope operator and guide show how they capture the wonders of the night sky. Join other members of AWB Affiliates around the world. Chat will be available between participants and with the telescope operator. Join in or just watch - should make excellent armchair astronomy!

For more information take a look at http://www.astronomerswithoutborders.org/.

Observational idea - Melotte 20

If you are looking for something relatively easy to show to people why not try Melotte 20 (also known as Collinder 39); this is an open cluster centred around the star Alpha Persei (or Algenib), the brightest star in the constellation of Perseus.

The cluster can be seen with the naked eye if you have a really dark sky, otherwise a pair of binoculars will show it in all its glory.

For more information about Melotte 20, take a look here: www.seds.org/messier/xtra/ngc/alphaper.html

From the Big Dipper to the Southern Cross

Scheduled for the 8th and the 10th of January, the "From the Big Dipper to the Southern Cross" project intends to bring the two hemispheres together - truly One People, One Sky!

For this project there will be two telescopes - one in the northern hemisphere and one in the south - on two different nights. No experience is needed. This is a chance to watch as an experienced telescope operator and guide show how they capture the wonders of the night sky.

Join other members of AWB Affiliates around the world. Chat will be available between participants and with the telescope operator. Join in or just watch.

For more information take a look at www.astronomerswithoutborders.org.

The observational blog site for the EAAE

Dear readers

As you know the EAAE is under big website transformations.
This blog has been built to provide observational alerts about astronomical events that can be seen during the following nights.
The responsible for this blog will be Bob Larcher an EAAE member that has a long term collaboration history with the French section of the EAAE and that is now part of the EAAE's webteam.

We hope you will enjoy it.