Astronomy – Around the Southern Cross

One of the most recognisable constellations in the winter sky is the Southern Cross, also known as Crux. It is so well known that it even appears on our flag, as well as on the flags of Australia, Brazil, Samoa and Papua New Guinea. Many people assume that you can’t see the Southern Cross in the Northern Hemisphere, but that is not true. If you are north of the equator, but south of a latitude of about 25 degrees, (Hawaii, parts of north Africa and southern parts of the USA) you can still see the Southern Cross.

It is not only the Southern Cross itself that is interesting, but also various objects around it which are visible with your binoculars or small telescopes. Many amateur astronomers learn where interesting objects are located by finding a constellation that we know well, and then learning about the objects near it.

Looking at the Cross, take a look at the star that is nearest to the pointers (on the left of the cross-piece of the cross). Right next to it is the magnificent Jewel Box cluster. This is easily seen with decent binoculars, but its true beauty is seen using a telescope – the reds, blues and white of the myriad of stars in the cluster looks just like jewels. Towards the south east of the Cross is a pear-shaped, inky spot, about as large as the Cross itself, that looks like a great black hole in the middle of the Milky Way. This is actually a dark nebula known as the Coalsack Nebula. In early astronomy, people thought that this was a hole in space, but we now know that it is in fact a cloud of gas and dust that absorbs the light of the stars behind it. The Coalsack is best viewed with binoculars.

Another interesting object near the Cross is one of my favourites – the Omega Centauri globular cluster. Draw an imaginary line going straight up from the top of the cross, and another from the furthest pointer, going right. Slightly above the point of intersection, you will be able to spot a fuzzy, faint cloud-like structure when using your binoculars. This is Omega Centauri. To really appreciate the sheer number of stars in this cluster, you would need to use a decent telescope. Directly below the centre point of the Cross, you will see another open cluster called the Pearl Cluster – best appreciated with a small telescope. It sits almost directly to the right of the Running Chicken Nebula, another beautiful object to see with your telescope. Those with binoculars can scan just below this nebula and will find the beautiful Southern Pleiades. This is also an open cluster and looks very similar to Matariki (the real Pleiades). This cluster is so bright and unexpected to see with binoculars, as it is hard to believe that it is not visible to the naked eye.

To help find these objects, use an astronomy app on your mobile phone: Starwalk on iPhones and Skymap on Android phones are good.

Hibiscus Coast Astronomical Society