This is a transcript of a podcast of the February 2011 night sky guide presented by Melissa Hulbert. Download and listen to the podcast as you gaze up at the night sky.
Hello and welcome to the night sky for February. My name is Melissa Hulbert and I’m an Astronomy Educator at Sydney Observatory.
Before we start our night sky tour, make sure you download the February sky map from our website at www.sydneyobservatory.com.au/blog. Or grab your copy of the ‘2011 Australian sky guide’ book which can be ordered from the website or bought at our Sydney Observatory or Powerhouse Museum shops. There is a lot of astronomical information in this book as well as the monthly star maps.
Armed with your sky map and a small torch with some red cellophane covering it, find a nice dark place away from the glare of the street lights and make sure you know your cardinal directions – that’s north, south, east and west. Remember that the Sun rises in the east, moves through the northern sky during the day and sets in the west or a small compass will also point you in the right direction. Pick a comfortable spot either on a rug or a deck chair that you can lay back in. Wait about 5 to 10 minutes and allow your eyes to adapt to the darkness.
Now turn lets turn towards the north. High in the northern sky is the familiar constellation of Orion, the Hunter. In Greek mythology, Orion was a hunter of great skill and boasted that he could kill all living animals. Gaea the Earth goddess was alarmed by his statement and fearing for all the animals on Earth she sent a scorpion to kill him. Orion was stung on the shoulder but was later revived and placed in the stars along with the scorpion. This entire myth is played out in the stars each year. As Scorpius the scorpion rises in the east, Orion sets in the west defeated. When Scorpius sets in the west the healer Ophiuchus crushes the scorpion into the Earth and revives Orion so he can rise in the east again. Orion appears in many cultures, even the ancient Egyptians saw Orion as Osiris, god of the underworld and of regeneration.
If you’re having difficulty picking out the hunter then look for ‘the saucepan’. This is a familiar group of stars for those of us in the southern hemisphere and is Orion’s belt and sword. Orion is upside down for us. Below ‘the saucepan’ you should see the red supergiant star Betelgeuse. Remember the scorpion’s sting? Betelgeuse has a distinct reddish tinge to our eye and is the shoulder or armpit of Orion. Above ‘the saucepan’ and diagonally opposite Betelgeuse is a brilliant white star – Rigel, one of Orion’s knees. Rigel is a blue-white supergiant star which is about 60,000 times more luminous than our own Sun. Rigel also has a small companion star which is best seen through a telescope though if seeing conditions are not the best, small telescopes will struggle to see the companion through the glare of Rigel.
Let’s return to the belt of Orion and follow its line to the west where we come to the back of a sideways ‘V’. This ‘V’ is the head of Taurus the bull who appears to be charging at Orion. Taurus, like Orion is also steeped in Greek mythology and represents the bull Zeus changed into to carry Princess Europa off to Crete.
Back to the ‘V’ which is part of a large open star cluster visible in binoculars called the Hyades. One of Taurus’ eyes is an orange giant star called Aldebaran which means ‘the follower’ and it too has a distinct orange tinge when viewed with the unaided eye. It follows the Pleiades, a wonderful open star cluster that can be seen with your eyes to the north-west of the ’V’. The Pleiades are known as the Seven Sisters as seven stars are readily seen with your eyes, but away from city lights, up to 13 can be seen with the unaided eye. The whole cluster contains about 100 stars and binoculars are the best way to view this marvelous object.
Make your way back to Orion’s belt and this time, follow the line of the belt in the opposite direction, towards the east. Here we come straight to a very bright white star. This star is called Sirius and is the brightest star in either Southern or Northern Hemisphere. It is bright because it is close to us – only 8.7 light years away or about 87 million million kilometres from us (and that’s considered close).
Sirius features strongly in mythology. To the Greeks it was the canine companion of Orion, but could also be Hermes, the guide to the dead. To the ancient Egyptians, Sirius originally represented Anubis who invented embalming and funeral rites, and guided you through the underworld to your judgement and helped weigh your heart to determine your fate in the afterlife. Later Sirius represented the goddess Isis and the Egyptians initially based their calendar on Sirius’ yearly motion around the sky.
Sirius is the brightest star in the constellation of Canis Major or the Great Dog and perhaps is best known to our younger listeners as a character in the Harry Potter books who is able to change into a large dog.
Let’s do an about face and turn to look at the southern sky. High in the south is a bright star, in fact the 2nd brightest in our sky – Canopus. Canopus is a white supergiant star and is 313 light years away. Canopus was the helmsman of the Greek King Menelaus and rather appropriately is now used by spacecraft as a navigational guide.
Canopus is the brightest star in the constellation Carina, which represents the keel of a boat. Originally it was part of the large constellation Argo Narvis which was the Ship of the Argonauts, which Jason and the Argonauts used in their quest for the Golden Fleece. So, nearby you will see Vela the sails and Puppis the Poop. In 1793 Argo Narvis was divided into the three constellations we see today.
If you are away from city lights you might make out two cloud-like shapes in the southern sky. A large one almost straight overhead in the southern sky and a small one a little lower and to the west. These are the clouds of Magellan, but they are not clouds. They are companion galaxies to our own Milky Way. They are gravitationally attached to our galaxy and we now know there is physical interaction between these galaxies and our own.
So what else can we look forward to seeing in the sky in February 2011?
This month after sunset, look towards the west and you will see a brilliant white star-like object. This is the largest planet in our solar system, Jupiter. By month’s end, the planet will only be visible during twilight as it will start to sink towards the horizon where it will eventually become lost in the Sun’s glare. So this is your last chance to catch Jupiter in the evening sky until August. Binoculars will show you the four largest moons known as the Galilean satellites and small aperture telescopes will show one or two of the Jovian cloud belts.
Turn towards the north-east and rising mid-evening is Saturn. Saturn is a wonderful object in a telescope as the rings and Titan (Saturn’s largest moon) can be seen even in a small aperture telescope. On the 21st, Saturn, the Moon and the star Spica will form a triangle in the sky.
February is also a great month for all you early-birds! In the eastern pre-dawn sky spectacular Venus is visible as it wanders through the constellation Sagittarius and the Milky Way. On the 5th Venus is between M20, the Trifid Nebula and M23 an open star cluster. While on the 12th, Venus is between M22, a globular cluster, and M25, an open star cluster.
Mercury is also visible in the dawn at the beginning of the month, after which it will again become lost in the Sun’s glare.
Mars also remains lost in the Sun’s glare this month and will not reappear in our skies until April.
I leave you now with a quote from Vincent van Gogh “For my part I know nothing with any certainty, but the sight of the stars makes me dream.”
Wishing you clear skies and see you next month under the stars!
If you have enjoyed this podcast and think you might want to regularly check out what’s in the night sky, why not purchase a copy of Sydney Observatory’s book the ‘Australian sky guide’ for 2011. It not only contains detailed monthly guides, but is jam-packed with astronomical information including rise and set times for the Sun, Moon and planets, tides, and a detailed look at our Solar System and upcoming astronomical events. Only $16.95 from Sydney Observatory and Powerhouse Museum shops or you can purchase it online (additional costs apply).
You can also subscribe free to our Sydney Observatory monthly sky guide podcasts through iTunes.
This has been Melissa Hulbert from Sydney Observatory with the February sky map podcast.