Astronomy Central

Wednesday 22nd February 2012

All times are GMT

 

Get yourself outside tonight if it’s clear, pull up a deck chair, and scan the star clusters, nebulae, and even see other galaxies with your binoculars. They are just perfect for some objects like the larger open clusters. Just aimlessly wandering along the band of the Milky Way is also very enjoyable. If you have binoculars up to 10 x 50 then they’re ideal for the job, portable, and easy to hold. Anything over this size will usually need a tripod. All the objects listed here are at their best in dark skies, ideally with the bright Moon not around.

 The Moon tonight… waxing crescent 3% full, setting in the west at 6.35 pm, and rising in the east at 7.20 am

 

The Pleiades Cluster

High in the southern sky early evening is the constellation Taurus, containing the one open cluster that lots of people can name and recognise, the Seven Sisters, The Pleiades, or M45. It’s one of the best sights in the night sky with your binoculars, showing a large glittering cluster. You can easily see it naked eye, as a large fuzzy patch of stars. M45 is a close open cluster at just 440 light years away, it’s one of the nearest and so appears large in the sky. The stars in the cluster are also very young at only around 150 million years, and the brightest ones you can see are also the very youngest and hottest. The “Seven Sisters” cluster actually contains up to 1,400 members. This attractive open star cluster fits nicely into your binoculars field of view, providing a very satisfying sight.

Tonight you’ll see the Pleiades Cluster high up in the south, where it’s at its highest point at 5.55 pm. It then decends towards the west during the evening, and sets in the north-west at 2.13 am.

The Pleiades Cluster is at magnitude 1.6

How long will it be around for? The Pleiades Cluster will still be around for some time, not going out of sight until mid to late April 2012 where it will disappear from view, into the glare of the setting Sun. Just before M45 goes out of sight it will make a really nice grouping low in the west, nearby Venus and Jupiter. On April 3rd Venus will actually pass right across the Pleiades, or at least extremely close to it

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Open Cluster M103

The great W of Cassiopeia is quite high in the north-west by night fall, and is a rich hunting ground with your binoculars. The plane of the Milky Way runs right through Cassiopeia, and so this is where open clusters can be found. One of these stellar jewels is open cluster M103 or NGC 581, one of the more distant of the open clusters at up to 9,000 light years away. It’s really easy to find, as it is close to the star that makes the left point in the W of cassiopeia. You’ll see it as a small hazy patch of nebulosity unresolved into stars, averted vision may be needed to get it to emerge out of the darkness, and a tripod for your binoculars would always be useful. This cluster has around 40 member stars, is 15 light years across, and a younster at only 25 million years old. Open clusters like M103 were formed from the same ancient cloud of gas and dust, with most of the cloud’s raw materials condensing down into stars…and very likely planets. Any remaining gas would have been blown away millions of years ago by the newly formed stars’ fierce ultra violet light and stellar winds.

To find M103 simply imagine a line drawn from the right point star of the W (Shedir), across to the left point star of the W (Ruchbah). Now continue on this straight line to a distance of 1 degree past the left point star to find this open cluster…1 degree is the width of your little finger held at arm’s length.

Tonight you’ll see the great W of Cassiopeia fairly high in the north-west after dark, as the night pregresses it drops close to the northern horizon before daybreak. Open cluster M103 is at magnitude 7.4

How long will it be around for? Cassiopeia is a circumpolar constellation from northern latitudes, meaning it never sets below the horizon. The constellation will be at its lowest point in the sky at around the end of April 2012, when it will be a little more than a handspan at arms length above the northern horizon.

 

The Sword of Orion

This very popular object is made for binoculars, a collection of star clusters and nebula. Appearing in the south after dark is the impressive winter constellation of Orion. This famous collection of stars is always spectacular, with the unmistakable straight line of the three stars of Orion’s belt, and the red supergiant star Betelgeuse at Orion’s left shoulder. If you look below the belt you’ll see Orion’s Sword, appearing to your naked eye as a line of three fuzzy stars. But when you look through your binos you will see that this is actually a group of star clusters, not individual stars. Notice how the middle cluster glows, especially with averted vision. What you are looking at is the famous, and probably most photographed deep sky object ever, the Orion Nebula or M42. This object is a huge and complex region of gas clouds, around 14 light years across. This place at 1,500 light years away is a vast stellar nursery, but it’s just one small part of an even larger region of gas that spans nearly the entire constellation. Newly born stars, and solar systems in formation have been observed in the Orion Nebula.

Tonight you’ll see the impressive constellation of Orion appearing towards the southern horizon by early evening, with the Orion Nebula in the middle of the sword climbing to its highest point in the south at 7.48 pm, it sets in the west at 1.28 am.

The Nebula can even be seen with the naked eye under very good skies, it is a magnitude 4.0 object

How long will it be around for? The Orion Nebula is in a winter constellation. So it will slowly and gradually move across the sky eventually sinking into the west by the end of April or beginning of May, when it will make way for the spring constellations rising in the east.

 

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The Beehive Cluster

The Beehive Cluster, Praesepe, M44, or NGC 2632 is a very nice and attractive open star cluster to look at through your binoculars, and does kind of look like a swarm of bees. The Beehive is another open cluster close to Earth, at 577 light years away in the constellation of Cancer. This puts it slightly further away than the Pleaides. M44 is now starting its rise in mid to late evening from the east. This cluster lies in the fainter constellation of Cancer, in between Leo, and Gemini. The stars that make up the head of Leo the Lion look like a large backwards question mark. You’ll find M44 with your naked eye roughly half way between this “question mark”, and the two twin stars of Castor and pollux in Gemini. The Beehive actually has over 1,000 stars, and is around 600 million years old.

Tonight the Beehive Cluster starts rising in the east before dark. It climbs to its highest above the horizon in the south at 10.44 am, and moves to the west as day breaks.

This object is at magnitude 3.7

How long will it be around for? The Beehive Cluster will now be in the sky until the beginning of June 2012, where it will be low in the west before eventually moving into the Sun’s glare. During the coming months it will gradually rise earlier and earlier, and climb higher into the night sky to make a nice binocular target.

 

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Double Star Albireo

If you look at the constellation Cygnus tonight and find the star that marks the “head of the swan” you’ll have the star Albireo, and it does actually look to your unaided eye as one faint single star. But this is probably the best known double in the sky, two stars seperated by 35 arc seconds. Get your binoculars on it and you’ll see straight away that there’s actually two different colour suns there (colours will be more subtle than image above), a brighter yellowish star called Albireo A at magnitude 3.1, and its fainter bluer companion star Albireo B at magnitude 5.1. It seems counterintuitive but colours red/orange/yellow are far cooler than blue when it comes to the temperature of stars. So fainter blue Albireo B is quite a lot hotter than its brighter yellow companion, with blue Albireo B also being a “Be star”, rotating at a speed of 250 kilometres per second at its equator.

The yellow star in the double actually is a double in itself with an orbiting companion star, but they’re much too close together to see with your binoculars.

At night fall look low to the north-west tonight and you’ll see Cygnus, as the evening progresses Cygnus moves lower towards the horizon, with Albireo setting in the north-west at 6.40 pm. Not at its best position for viewing right now, as Alberio has set by mid evening, but it rises again from the north-east at 12.36 am making Cygnus visible low in the morning skies in the north-east up to daybreak. The figure of the swan appears to be flying away from Cassiopeia, so it’s easy to find the head star Albireo.

 

 

Open Cluster M39

Open cluster M39, or NGC 7092 is a nice little collection of stars right in the band of the Galaxy, giving you a backdrop of more distant suns. It is in Cygnus (see position of M39), a great constellation in its own right to spend time in as the Milky Way goes along its length. Look for the distinctive shape of this constellation, it resembles the shape of a cross, or of course what it’s meant to be…a swan. Unlike a lot of constellations it does actually resemble what it’s meant to be, a swan as it flies away from Cassiopeia. From the tail star of the swan (Deneb), along the body, to the head (Albireo) forms roughly a straight line. The back of your fist held at arm’s length makes 10 degrees of sky. The open cluster M39 lies just under the width of your fist from the tail star of the swan (Deneb) in the direction of Cassiopeia, then about 3 degrees lower.

Open cluster M39 is 800 light years distant, and its stars are about 300 million years old. It has between 30 and 50 stars forming an attractive triangular shape.

Tonight open cluster M39 is fairly low in the north-west after sunset, above the tail of the swan in constellation Cygnus  . It then moves to its lowest point in the north by 11.34 pm before then rising to a modest height in the north-east as day breaks. M39 is at magnitude 5.5

How long will it be around for? This cluster will be on view for some time, and it’s circumplolar from northern latitudes meaning it never actually sets. It will get to its lowest point on the northern horizon in April 2012, before starting its rise again.

Galaxies M81 & M82

These two galaxies 12 million light years away are one of the best sights you’ll see through a telescope. Two island universes in the same view, separated by 130,000 light years.  But they can actually be glimpsed with binoculars in dark skies. They are the “grand design” spiral galaxy M81 at 36,000 light years across, and smaller irregular starburst galaxy M82. They are in Ursa Major, and their proximity to each other is causing them to gravitationally interact. This interaction is causing intense star burst in M82, just at the galaxy’s centre new suns are being born 10 times faster than in our entire Milky Way.

They’re not really close to any easy marker points in the sky. But if you  draw a line from the bottom left star of the bowl of the “Big dipper” (Phad) to the top right star at the bowl edge (Dubhe), then carry that imaginary line about the same distance again, you’re in the place in the sky for M81 and M82. Although right now Ursa Major is still fairly low in the north having passed its lowest point in the sky for the northern hemisphere in mid September, it is now starting its rise again getting to a nice height above the horizon by midnight.

In your binoculars they will appear as two small fuzzy shapes close by each other, and you should notice they are different shapes. Spiral M81 is the brighter of the two at magnitude 7.0, and the irregular star burst galaxy M82 is slightly dimmer at magnitude 8.4, M82 is also called “The Cigar galaxy” for its shape. It takes practise to find these, and yes they will appear as two small fuzzy smudges. But those two fuzzy smudges are entire galaxies in interstellar space, and you’re seeing them with your own eyes with just a pair of binoculars. The star light from two stellar systems 12 million light years away.

By nightfall the Ursa Major constellation is fairly low in the north-east, but during the evening it climbs higher, eventually getting to virtually directly overhead by the pre dawn hours.

How long will it be around for? Galaxies M81 and M82 are circumpolar in the northern sky, meaning they will always be above the horizon never setting. The best time to see them are when the bright Moon is not around, and under dark skies away from light pollution.

M13, The Hercules Cluster

This famous globular cluster at 25,000 light years away is a classic of the northern skies, and if your first view of it is from a really dark site with a larger pair of binoculars, I promise you will not forget it. It’s well worth getting away from light pollution to see it. In clear dark skies through your binoculars you should see a quite bright, fuzzy, but crisp, glowing “ball of suns”, although individual stars will not be resolved. This globular cluster contains over a million stars all packed into a region of space 145 light years wide. Space is so limited here that stars are thought to collide in the centre, producing bluer suns called “Blue stragglers”. Globular clusters like M13 are not actually part of the Milky Way’s disk, but reside far above and below the spiral arms, surrounding the Galaxy in a halo. Their stars are known to be very old, and in 1974 a message was sent to the Hercules Cluster in the hope that an intelligent civilisation might live there.

The way to locate M13 is to find the Hercules “keystone”, this is four stars making a rough square 5 or 6 degrees across, at the centre of the Hercules constellation. In this map you’ll see M13 marked about a third of the way between the two right hand, (or uppermost right now) stars of the square. Look at Ursa Major, or “The Plough” and the first two stars of the handle that are attached to the “bowl”, make a straight line. This line points to the centre of Hercules. The keystone can be slightly difficult to find at first especially in more light polluted skies but once you get the hang of it, it becomes easy.

A late riser this one at the moment, tonight the Hercules Cluster M13 starts its rise from the north at 7.31 pm, it hugs the north-east horizon up to late evening, but then climbs high in the east up to day break.

M13, or The Great cluster in Hercules is a magnitude 5.9 object, and it is even visible naked eye under very good skies.

How long will it be around for? The Hercules Cluster M13 although not perfectly placed right now for totally convenient viewing at the start of the year, is known as one of the classic objects of the spring sky. So as we move out of winter, keep your eyes peeled for this one. You have bags of time to see this famous globular cluster as it will be at its prime right through spring, moving to a beyond midnight object during summer.

The Andromeda Galaxy, M31

Now moving lower in the west is Andromeda, or M31, the main large neighbouring galaxy of the Milky Way. It is a huge spiral galaxy 2.5 million light years away, with up to one trillion stars, and a diameter of possibly up to 220,000 light years. It’s more than twice the size of our Milky Way some think, others disagree saying it’s around Milky Way size, Andromeda’s size is a debated subject. Now positioned well, high in the sky, you can quite easily see Andromeda naked eye as a fuzzy glow from a dark site. In fact if you know where exactly it is, you can pick it out even from an area that has some light pollution with averted vision.

There there are two main ways to find this island universe in the sky. One is to locate the large square of Pegasus with its four stars marking each corner. You’ll find Pegasus to the east of Perseus, and Cassiopeia. The star at the left of the square is called Sirrah (or Alpheratz), look to the left of Sirrah and you’ll see three stars in a line, a dimmer star and two  bright stars. The first bright star is Mirach. Now look above Mirach and you’ll see a dimmer star, look about the same distance above again from the dimmer star, and here is located the Andromeda Galaxy (M31). Another way to find M31 it is to use the right hand V of the W of Cassiopeia and imagine a line pointing down, this V points just to the left of Andromeda.

Get your binoculars on M31 and you’ll see the bright core of the galaxy as a small fuzzy blob. But keep studying and use averted vision, and you’ll soon start to make out the fainter shape of the galaxy’s disk extending out from the core. This is an object far outside the Milky Way, an entire ”island universe”. To be seen at its best Andromeda should be observed with the bright Moon absent under dark skies, but it’s still visible even from urban areas.

Tonight you can see M31 the Andromeda Galaxy in the west by nightfall, during the night it continues to sink lower, and by the pre dawn hours is sitting on the northern horizon. M31 the Andromeda Galaxy is circumpolar, meaning it never actually sets in northern latitudes.

M31 is at magnitude 3.4

How long will it be around for? Right now the Andromeda Galaxy is visible towards the west/north-west. This object is actually circumpolar from northern latitudes so never goes below the horizon, but by the beginning of April it will be placed at it’s worst position to see, being very low to the northern horizon.

The Perseus Double Cluster

This cluster is one of my favourites, it looks stunning in a telescope at low power, but binoculars also show it well. The Perseus Double Cluster, NGC 884 and NGC 869, or H and X Persei are actually two seperate open star clusters close to each other in space at around 7,000 light years away. They are only a few million years old, much younger than the Pleaides. To find it I could tell you to find this star, draw a line to that star etc, but the easiest way I have found to locate the Perseus Double is just to look for a fuzzy irregular patch in the band of the Milky Way between Cassiopeia and Perseus, (cluster marked as H+X on Perseus map). Once you see it, get your binos on it and you’ll see two very attractive open clusters of sparkling stars set against the blackness of space. There’s also a nice line of stars that curves away from the upper most cluster, when you see this line of stars you’ll know you have this popular deep sky object in your view.

Tonight you’ll see the Perseus Double Cluster very high in the west after dark, nestled between Pereus and Cassiopeia. During the night it moves lower to the north in the early hours. The Perseus Double Cluster never sets as it is circumpolar meaning, it’s always above the horizon from northern latutudes.

This open cluster is a magnitude 4.00 object

How long will it be around for? Like Andromeda, the Perseus Double Cluster will always be above the horizon as it is circumpolar from northern latitudes. It is perfectly placed for viewing right now, and will get to its lowest point in the sky in the north by April 2012, before rising higher again.

 

Jupiter

Do you think you can only see Earth’s moon with your binoculars? Think again! It’s often suprising to people that if you take a look at Jupiter you can not only see the small disk of the planet but also its four moons Ganymede, Callisto, Io, and Europa as pinpoints of light on either side. Obviously the bigger the binoculars you use the better, you may even be able make out a hint of the cloud belts of the planet. But whatever binos you have, give Jupiter a go as the moons are a continuously changing scene as they orbit the gas giant.

Tonight the solar system’s biggest planet is in the south-west after dark looking like a bright star that doesn’t twinkle. Venus (if not set) will be blazing much brighter, lower down to its west. Jupiter is visible for a good part of the evening, it moves across the sky to eventually set in the west at 11.15 pm.

How long will it be around for? Jupiter will be around until May 2012 where it will go out of sight in the west. Opposition came on October 28th 2011, so although still very obvious in the sky, Jupiter will now be very slowly be decreasing in brightness.

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