The Night Sky for June, 2010

Summer begins this month, and because the Sun is not setting until after 9pm, 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.

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.

Mercury & Venus in the evening sky

The next few weeks are an ideal time to see Mercury & Venus together in the evening sky.

Mercury is always a difficult planet to find. It is the closest planet to the Sun, and so it always remains close to the Sun in the sky, usually totally hidden in the Sun's glare. But at the beginning of April (as the simulation below shows), Mercury gets to its Greatest Eastern Elongation, meaning that it is as far away eastwards of the Sun as it is ever going to get, and so it is the best time to see Mercury in the evening sky.

So wait for the Sun to set, and then go out and see if you can see Mercury for yourself! The best days to look are the 15th and 16th of April, when the Moon acts as a useful guide. This will be your best chance to see the elusive Mercury!

Each frame in the simulation above is a view looking west when the Sun is 6 degrees below the horizon (about 40 minutes after sunset) - that's dark enough to see Venus and Mercury, but not so late that they are hidden behind trees. The simulation was done using Stellarium.

Happy Spring Equinox!

Today, the 20th March, the spring equinox occurs at 17:32. That is the time when the Earth is neither tilted towards, or away from, the Sun, giving us an equal length day and night - hence the name, Equinox!

Venus is back!

In January, Venus was on the far side of the Sun and totally hidden in the glare of the Sun.

But now it is back! Take a look in the evening sky for a glimpse of the brightest planet...

Venus will be a prominent member of the night sky throughout the summer until the end of August. If you have a zoom lens on your camera you may be able to just make out the crescent of this planet, which is very obvious with even a small telescope. Our view of Venus' crescent will change over the next few months, as it orbits the Sun. The animation below shows this in more detail.

Venus began 2010 on the opposite side of the solar system to the Earth, which is why we could not see it. By March 2010 (when the Earth is at the 11 O'clock position in this animation), Venus became visible in the evening sky.

By 20 August 2010, Venus will reach its maximum Eastern position from the Sun (when the Earth is at the 5 O'clock position on this animation). And then Venus rapidly "catches up" with the Earth, being between the Earth and the Sun on the 29th October, 2010.

The animation then returns to the beginning of the year to watch how the phase of Venus (what fraction of Venus is illuminated) changes during 2010.

But by October, when Venus is between us and the Sun, we will only be able to see the night-time side of Venus. (Venus will also appear to get larger in size during the course of the year).

International Space Station

To see a satellite, it must fly over head at either dawn or dusk - when it is dark enough for us to see them, but when sunlight can still shine onto the satellite (for instance, if a satellite flies over-head at midnight, it is in the shadow of the Earth for the entire flyby).

Sometimes, a particular satellite will fly over-head at midday when the daylight is too bright; sometimes it might fly over at midnight when it cannot reflect sunlight.

You might have seen satellites flying over-head yourself and just not realised what you are looking at. The rule of thumb is - if it is flashing, it is an aircraft, but if it is at a steady brightness, then you are looking at a satellite!

For the next week, the International Space Station is ideally placed to be seen flying directly over the UK! The approximate dates and times are listed below...

Date	Time, direction (and altitude) of...
	Appearance	Highest point	Disappearance
8 March	19:26 West (10°)	19:29 South (73°)	19:30 East (52°)
9 March	18:16 South-West (10°)	18:19 South (42°)	18:22 East (10°)
9 March	19:51 West (10°)	19:54 West (70°)	19:54 West (70°)
10 March	18:41 West (10°)	18:44 South (75°)	18:46 East (13°)
11 March	19:06 West (10°)	19:09 North (85°)	19:11 East (23°)
12 March	19:31 West (10°)	19:34 North-West (89°)	19:34 East (47°)
13 March	18:20 West (10°)	18:23 North (85°)	18:26 East (10°)
13 March	19:55 West (10°)	19:58 South-West (61°)	19:58 South-West (61°)
14 March	18:45 West (10°)	18:48 South (89°)	18:51 East (12°)
15 March	19:10 West (10°)	19:13 South (61°)	19:15 East (20°)
16 March	19:35 West (10°)	19:37 South (32°)	19:39 South (24°)
17 March	18:24 West (10°)	18:27 South (59°)	18:30 east (10°)

For other times and locations, see the SpaceWeather flyby predictor.

The Night Sky for February, 2010

The highlight this month is the planet Mars. Easy to spot as a bright red object in the night sky, visible in the east at sunset, moving to the south at midnight, and heading further west in the morning hours. And, because both the Earth and Mars are on the same side of the solar system at the moment we are quite close to Mars, making Mars look brighter in the evening sky, and big when you look through a telescope.

This why there are some fantastic images of Mars being taken recently, including this one from local astro-photographer Pete Lawrence, showing a dust devil that has pasted across the martian south pole (more details at SpaceWeather.com).

By 10pm, the planet Saturn is also rising in the east. The rings of debris that surround this planet are visible through binoculars if you have good eyesight, or easily through a small telescope to the rest of us.

Orion (the hunter), Taurus (the bull) and Canis Major (the great dog) are the dominating constellations this month, with the bright star Sirius forming the nose (or sometimes the collar) of the dog. You should not miss out on looking at the Pleiades or the Orion Nebula through binoculars, and notice how Sirius twinkles due to our turbulent atmosphere.

To find these objects, I recommend that you use either Stellarium or SkyMaps.com.

Annular eclipse of the Sun: January 15th 2010

On Friday, there is a Annular Eclipse of the Sun, from 04:05 GMT, with mid eclipse at 07:07 GMT, and ending at 08:59 GMT... yes, that's in the middle of the night for us here in the UK, so unfortunately, we will not be able to see it at all! (and even when the Sun is visible at the end of the eclipse, the Moon is slightly off to one side as seen from the UK)

The eclipse will be visible from Africa and across India, as show in the map below.

Below is an animation I made from a series of photographs taken during the annular eclipse of 2005. The reason it is an annular, and not total, is that the Moon orbits the Earth not in a circle, but in an ellipse. During this eclipse, the Moon is slightly further away than on average, making it appear slightly smaller, and so too small to cover the Sun completely.

More details can be found on the Wikipedia.

If you do happen to be in the path of the eclipse, do not look at it with your eyes, since you will probably be blinded for life. Instead, use solar glasses, a simple and cheap solar telescope, or just use your hands as a pinhole projector!

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.