July 2008 night sky podcast transcript

This is a transcript of a podcast of the July 2008 night sky guide. Download and listen to the podcast as you gaze up at the night sky.

Stephanie Parello: This is the guide to the night sky for July 2008. My name is Stephanie Parello. I’m Senior Astronomy Educator at Sydney Observatory. If you’d like to become familiar with the night sky, you’ll want to spend some time outside at night. But first, get ready with a few simple things. Print off the sky map at www.sydneyobservatory.com/blog and download this podcast. Prepare a torch fitted with a red filter. You can use red cellophane or tissue paper and secure it with tape or a rubber band. This is important because you want your eyes to adapt to the dark so you can see as much as possible in the night sky and the red light helps keep your dark adaption better than white light. Next, dress warmly and grab your gear. Go outside on a cloudless night, sit or lay yourself down comfortable, look up and listen to this guide.

Now what? Do you know where the sun set? I hope so, because that’s going to help you find your way around now. The sun sets in the western part of the sky. In July it sets a bit north of due west – but that’s not going to mess us up. Once you know where west is, the other directions fall into place. Facing west, north is to your right, south is to your left, and east is behind you. Of course you don’t have to face west the whole time. Just so long as you remember which direction is which.

July is a good month to look at the sky. We have the constellation of Scorpius, the Scorpion, very prominent. This is a very important feature of the Australian winter sky. Scorpius is high in the eastern sky. It’s lying on its side with its claws a little bit upwards on the left. And the curved tail is on the right hand side. It’s a very obvious constellation because it’s made up of a curved line of bright stars and it’s useful to become familiar with because once you’re familiar with it then you can look to either side and become familiar with other stars or constellations around it.

The heart of the Scorpion is the red star, Antares. This is a giant star, many hundreds of times wider than our own Sun. It’s a star near the end of its lifetime. Even though it’s a giant star, highly bloated, its surface is considerably cooler than our own Sun and so it has this red colour. In the eastern sky, there’s a group of stars known as the Teapot because if you look at it, they very much look like a teapot. In this position, it’s standing on its handle with the spout on top. The Teapot is an asterism or a picture in the stars that actually looks like what we call it. And this particular asterism of the Teapot is part of a larger constellation named Sagittarius, the Archer.

Going over to the southern sky where the Southern Cross is high up…. The constellation of Crux, as the Southern Cross is formally known, Crux is the smallest of the 88 internationally recognised constellations in the whole, entire sky. Size is no measure for this important collection of stars. The Southern Cross should be very familiar to everyone as, of course, it’s on the Australian flag. It can be confused with a number of other stars nearby that are often known as false crosses. But the Southern Cross itself is a very small, very tight, bright group of stars and it has two bright stars pointing towards it known as the Pointer stars. The closest Pointer star to Crux is known as Beta Centauri and the brighter one, a little farther away from Crux is Alpha Centauri. Named because they are the two brightest stars in the constellation of the Centaur. Alpha Centauri is the closest star system to our Solar System. If you look at Alpha Centauri through a small telescope, then we can see two stars very close together. There is a third star in the system, rather distant from these two, and it’s not probably in the field of view of your small telescope. It is a little bit closer to the Earth than the other two, so you may hear that the closest star to our Solar System is Proxima Centauri. And it’s this third star in the Alpha Centauri triple star system. The light that has left the Alpha Centauri star system left about four years ago, and that’s what you’re seeing tonight.

In the northern sky, quite prominently, you’ll see a slightly reddish star, almost due north, high up. That’s Arcturus, the brightest star in the constellation, Boötes, the Herdsman. The name Arcturus comes from Greek, and means ‘bear-watcher’ or ‘bear-guard’. It’s called this since it circles the north polar region which contains the constellations of Big Bear and Little Bear. Of course, here in Southern Hemisphere, we cannot see those bears. Arcturus is a giant star with a width 25 times that of the Sun and is relatively close to us at a distance of only 37 light years.

This month’s planets include: Venus, low in the north-west during the first week of July. It starts in Gemini, moves across Cancer, and reaches Leo by the end of the month. On 4 July, a very thin crescent Moon is above and to the right of Venus. Mars is also in the north-west in Leo, passing the bright star, Regulus, on the 1st and 2nd July, less than two Moon-widths apart. On 6th July, the crescent Moon is below and to the left of Mars. And on 10th and 11th July, Mars passes less than two Moon-widths from Saturn. Jupiter is low in the east in Sagittarius. On 17th July, a nearly full Moon is above and to the right of Jupiter. Saturn is also in the north-west in Leo. On 7th July, the crescent Moon is directly above Saturn.

Note that the Sun sets about 5pm in July, and it gets dark about 6pm. Also on the 4th, Earth is its farthest distance from the Sun at 6pm.

This completes the guide to the night sky for July 2008. You can find this guide to the night sky at the Sydney Observatory blog, which is – www.sydneyobservatory.com/blog.