Andromeda Galaxy

The Wonders of Andromeda

By Andy Fleming on | From andromedachild.com

How the Andromeda Galaxy reveals itself through standard sized binoculars (say 10x50s). For reasons that are mainly due to the human eye's sensitivity to low colour light levels, deep sky objects such as galaxies and nebulae appear as in greyscale through both binoculars and telescopes. This is due to their low surface brightness... we've all been spoilt by DSLR camera and CCD images!

ANDY FLEMING takes a look at a constellation everyone can see without optical aids, and how at a dark site if you follow the instructions you’ll observe the most distant object you’ll ever see with your naked eyes: the Great Spiral Galaxy in Andromeda.

Okay, so I’ll admit it. I share the typical mammalian trait of laziness including when it comes to observing the night sky. I also exhibit a modicum of tightness when it comes to spending money on equipment in our damp and cloudy climate. So I’ll use the excuse straight away of two eyes being better than one, and say that even with my superb eight inch Newtonian reflector, my enjoyment of the night sky still comes primarily from a pair of 10 x 50 Super Zenith binoculars that I purchased for a fiver at a local car boot sale. They are light, portable and require no setting up.

These binoculars have, over the past four years facilitated access to some stunning clestial sights, often when the use of my telescope has been impractical, such as when I’ve been out walking our dogs, or during those all-too-brief clear spells. They are also nicely portable for a quick to get away from the worst of the Teesside light pollution.

One of my favourite constellations is Andromeda, well it has to be hasn’t it... just consider the title of my blog. And I thought that the time had come to pay homage to this constellation upon which my literary internet presence is based.

How to locate the Constellation of Andromeda in the night sky. Image courtesy of Stellarium Planetarium Software (screen dump).

The constellation of Andromeda is located in an interesting part of the sky, being flanked celestially by the constellations of Cassiopeia, Pegasus, and Perseus. It is a circumpolar constellation which means it can be viewed the whole year long in mid-northern climes. It also possesses a rather interesting legend that has been passed down to us from antiquity, infact it is one of the most famous of all the Greek celestial legends. It’s also a fascinating constellation because within it is located the spectacular great spiral galaxy M31 visible with the naked eyes and the other giant spiral galaxy along with the Milky Way in our local cluster. It is the most visible galactic deep sky object seen from the northern hemisphere.

And so to that fascinating Greek legend which has it that Perseus, killer of the Gorgon, Medusa, had a glance that could turn anyone to stone. He also possessed an unfair advantage, as the gods had provided him with a pair of winged sandals and a shield that he could use to locate Medusa (thus looking only at her reflection, and not the Gorgon herself). After neatly slaying Medusa, Perseus was returning home when he saw the beautiful Princess Andromeda, inexplicably tied to a post on the seashore. It turned out that Andromeda’s mother, Queen Cassiopeia, had fallen foul of the sea god Poseidon, and as a punishment, Cetus, a monster had been sent to ravage the country. King Cepheus, after consulting an Oracle was told that the only way to placate Neptune was to sacrifice his daughter to the monster.

However, a timely appearance was made by Perseus who turned the beast to stone and then married Andromeda. All the major players in this fairly unique happy-ending were thus cast into the sky by the Greeks, and all can be seen around Andromeda. Even the sea monster, Cetus, is on view, although he was relegated to the status of a harmless whale! Such are the outcomes of Greek myths!

And so to the jewel that is Princess Andromeda’s crown, the Andromeda Galaxy, and my easy instructions for its location at-a-glance. Bear in mind that to view this object with the naked eyes you do need to view the night sky at a reasonably dark site. You will have difficulty observing it in the centre of an urban area... the suburbs or local countryside will prove to be much more successful.

How to locate the Andromeda Galaxy (M31) in the night sky. Image courtesy of Stellarium Planetarium Software (screen dump).

Firstly look for the constellation of Cassieopia, the great ‘W’ in northern hemisphere skies. Once again like Andromeda it is a circumpolar constellation at mid northern latitudes. Well below Cassieopia, and slightly to the right, in an area devoid of bright stars, you will see one lonesome bright orange star, the double star Mirach (Beta Andromeda). Star hop up and slightly to the right two faint stars (Mu and Nu Andromeda) are visible. Slightly to the right of Nu is a faint star-like speck – that’s the Andromeda Galaxy (Messier object 31, or just M31). This of course is not the only method by which to find our closest galactic neighbour, but it’s the one that I personally find easiest.

But take a look at it through any common or garden binoculars and you’re in for a jaw-dropping sight. What you see is a large hazy nebulous-looking entity that in fact is a part of a gargantuan star city containing hundreds of billions of stars... it is the central bulge of this fabulous spiral galaxy. Some more details are revealed with a telescope with a low power eyepiece, but in truth I’ve always found M31 a disappointing telescope target – it’s definitely far better with binoculars due to their intrinsically larger field of view.

As you view our beautiful galactic neighbour, consider that its distance from the Earth is approximately 2.5 billion light years. In other words light the fastest thing we know with a huge velocity of 186,000 miles per second has taken 2.5 billion years to reach our eyes from the Andromeda Galaxy. The light from it we see today left M31 before humans had evolved from apes! In motorway terms its distance is a staggering 14,750,000,000,000,000,000 miles! In space it's a long way between service areas!

There is one final twist in this tale of cosmic distances. The Andromeda Galaxy is on the move – and quickly at 120 kilometres per second. And it’s coming towards us! In 3 or 4 billion years from now our own Milky Way and M31 will merge in a celestial show of galactic cannibalism. Will our solar system and the Earth survive?