“Just So Science” – The Hunter and the Bull

By Elf Eldridge 15/04/2011

My astronomy posts are based on what I talk about each week at Carter Observatory during planetarium shows and telescope viewing  sessions. Much of the information is gleaned from the monthly summaries provided by the excellent Alan Gilmore at the University of Cantebury’s Mt John Observatory which can be accessed (for April) here:  http://www.rasnz.org.nz/Stars/EveningSky/Apr11Sky.html

Personally I remember the main stars, and their colours an then use imaginary lines to navigate the sky, unfortunately this is not particularly well facilitated by the currently available star chats (which are still great though), visible on the right,  so I will be editing small portions of the star charts, to allow colour comparison and for general ‘prettyness’ (and also to teach myself Inkscape – BTW if you would like to similarly learn here‘s a nice place to start!)

orion overview

Sadly, as we enter into the thrall of Winter we begin to lose one of the most striking, and easily identifiable, constellations from our North Western sky: Orion. He is, after all, our summer constellation and so he flees behind the Western horizon reasonably early on in the evening and will almost completely disappear from our night skies by the end of the month. Most recognize him by his ‘belt’ of 3 bright stars in a row – which is incidentally almost the exact translation of its Maori name: Tautoru.


Take solace though as Orion will reappear in our morning sky later in the year and features prominently in Matariki celebrations as Tautoru takes its role as one of the ‘Pillars of Light’ separating Ranginui from Paptuanuku – but more on this later!

Orion’s Belt is a great way to navigate and memorize his part of the sky. On either side of it sit two bright stars: one sporting  a brilliant blue hue, called Rigel, (Orion’s ankle) with special significance to many Iwi as its rising later in the year can mark the beginning of the traditional new year, instead of Matariki. The other is a deep luscious red, by the name of Betelgeuse, affectionately known as ‘Orion’s Armpit’.

Following the 3 stars in the belt out in one direction leads you to ‘Sirius‘, the brightest star in our night sky. Sirus is the main star in the constellation of Canis Major, Orion’s large hunting dog.

Following the line the other way will point you to medium brightness Red star: Aldebaran (NOT Alderaan which is a mistake I keep making!), the main star in the constellation of Taurus, one of the signs of the Zodiac. This brilliant red star is Taurus’ ‘eye’.  Just to the side of Aldebaran (the Rigel side) is a group of fainter stars shaped like a sideways “V”. This is the famous Hyades, a gorgeous star cluster roughly 150 light years away from earth.

Taurus, the Bull
Taurus, the Bull

The Hyades mark the ‘face’ of Taurus – then his horns extend out ‘below’ [at the moment] Orion into two bright stars. These stars aren’t particularly notable themselves (well, you know APART from being giant balls of gas casually fusing elements together, one being 5,700 times brighter than the sun), but next to the top horn (the one closest to Orion) is the Crab Nebula (a.k.a. M1). The entire point of this post was actually so I could just use this image as it’s one of my favourites!

Crab Nebula (M1) - False Coloured image
Crab Nebula at various wavelengths

M1, is the remains of a supernova, the explosion of a massive star at the end of its life due to the gravitational collapse made possible by the star running out of fuel and losing the ‘Radiation Pressure‘ it requires to remain stable.

Personally, I just call it pretty damn spectacular!

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