The Night Sky for June, 2010

Summer begins this month, and so the Sun is not setting until after 9pm, and darkness does not begin until 10pm. But there is plenty to see this month if you are willing to stay up a bit later.

As soon as it begins to get a bit dark, look towards the sunset, and by 10pm you will be able to see the planet Venus, very low in the sky. It looks a bit like an aircraft coming in to land… but if it is still there 10 minutes later, and hasn’t landed, then you have found Venus!

Look to the left of Venus, and slightly above it, and you will notice a red object – the planet Mars. During the month, Mars is close to the star Regulus, at equal brightness but not as red. On the 6th of June, Mars passes only 1 degree away from Regulus as it moves around the Sun and so moves around the sky.

Then look to the top left of Mars, and you have Saturn, which appears to be quite bright and slightly yellow in colour.

Venus is setting at about 11.30pm, with Mars following it an hour later, and then Saturn is setting an hour after that.

The positions of the planets can be seen in this movie below.

If you now look in the other direction towards the stars rising in the South-East (see graphic below, set at 22:30BST), you will see three bright stars – Deneb, Vega and Altair. Those three stars are known as the summer triangle of stars, and are fascinating in their own right. Vega has a dusty disk around it and maybe a planet; Altair rotates in just 7 hours, making it bulge around its equator; and Deneb is one of the brightest stars we know of. Deneb is over a 100 times further away than both Vega and Altair, but it looks equally bright because it is so big – at least 200 times the diameter of the Sun! If Deneb was as close as Altair, it would be almost as bright as the full Moon!

I will be writing more about what can be seen in this patch of sky over the coming months, as the Earth moves around the Sun to get a better look at this patch of the night sky.

Plenty of Planets!

Now is a great time to feel that you are part of the solar system. Venus, Mars, Saturn and the Moon are all visible in the evening sky. As you can see in the photograph I took a few nights ago (below), all the planets lie along a line called the ecliptic, which goes to show just how flat our solar system is. (Just hover your mouse over the image for labels)

Our solar system is like a big flat pancake! Imagine the Earth sitting on that pancake, along with the rest of the planets. The grid marks where that pancake (the flat plane of our solar system) goes out into space, and so where all the planets can be found. The constellations of Leo (top left) and Gemini (bottom right) are also shown.

The following animation shows just how it looks from the ground and from above the solar system.

The Night Sky for May, 2010

This month is a great month for planets! If you go out on a dark night you can see and feel for yourself how we are part of the solar system.

Look low in the west, half an hour after sunset, you can see Venus - the brightest object in the sky after the Sun and Moon. Now wave your arms around in an arc going from Venus low in the west, over the south and then towards the south-east, and you will bump into two more planets in the night sky – the red planet Mars, and Saturn which is yellowish in colour.

Ancient people knew of the planets Mercury, Venus, Mars, Jupiter and Saturn because they are all so easy to see with your own eyes - they are all bright objects that can even be seen through our light polluted skies. However, Mercury cannot be seen at the moment since it is too close to the Sun (Mercury passed between us and the Sun on the 28th of April), and Jupiter is above the morning side of the Earth, and so we can only see Jupiter very early in the morning.

But do take a look for Venus, Mars and Saturn, the bright planets in this months evening sky. They are forming a beautiful arc across the night sky, which really highlights that we live close to the centre of the very flat solar system.

The Night Sky for March, 2010

March is one of the best times of the year for astronomy, simply because there is so much to see!

Orion and Taurus – along with all the amazing objects that surround that part of the sky, such as Orion's nebula, Betelgeuse, the Pleiades - are visible in the evening, and as they set by midnight, the summer highlights begin to rise in the east – Hercules, the Great Globular cluster, with Vega and the rest of the summer triangle on their way from the morning sky into the evening sky, signalling that summer is not far away.

We can see both Mars and Saturn throughout the night, with the latter rising at sunset. The Moon glides under Mars on the 25th March, and then passes under Saturn a few days later on the 29th. Both Mars and Saturn are quite bright, so they are easy to spot.

For more details, I recommend you use the free planetarium software Stellarium – you can download it for Macs, Windows or Linux.

The Night Sky for January 2010

We have two evening sky planets that we can see throughout January - Jupiter in the early evening, and Mars (right, as seen through a good telescope) in the late evening. You can see Jupiter setting in the South-West if you look before 7pm, and you can see Mars rising in the North-East if you look after 7pm. So, for a few minutes at around 7pm, you can see two very bright planets at opposite sides of the sky!

On the 17th, the Moon is just to the right of Jupiter, and on the 18th the Moon has moved just above Jupiter. By the 29th of January, the Moon will have travelled to the other side of the sky and will be next to Mars for the night. Saturn is also visible over night, now rising just before midnight in the south and visible until dawn. Unfortunately, we cannot see either Mercury or Venus this month, as they are both too close to the Sun.

The starry highlight of January is still the constellation of Orion, which I discussed in last months's blog.

Water, water, everywhere...?

We believe that water is one of the key ingredients for life, and this is often discussed in schools, and so it have been interesting to hear the reports of water on the Moon and Mars over the last few days.

Last week, the Indian Chandrayaan-1 lunar orbiter discovered that areas of the lunar surface are slightly damp... slightly meaning that the Moon is still dryer than the driest of Earth's deserts! But there is water present. Full details of that can be found on the Astronomy Picture of the Day site.

Orbiting Mars, NASA's Mars Reconnaissance Orbiter has discovered 100 fresh meteor impact craters. On Earth, most meteors burn up in our atmosphere, and do not reach the ground. But the atmosphere of Mars is much thinner than ours, allowing far more meteors to hit the surface. And when a crater is formed, you can see what is just beneath the martian surface... and it appears to be ice. More details of this story at the NASA-Science website.

This also implies that had the robotic arm on NASA's Viking 2 (which landed on Mars back in 1976) been just 10 cm longer, it might have struck ice!