More International Space Station fly-pasts...

The International Space Station will be visible flying over the UK for another week (before it starts flying over in daytime), so do take a look... and don't forget to wave at the six astronauts currently on board as they fly overhead!

The space station orbits the Earth every 96 minutes, but for us to clearly see it, the ISS needs to fly over at dawn and dusk. We see the space station thanks to sunlight reflecting off it, mainly off the huge solar panels the size of a football field. If it flies overhead in the daytime, the sky is too bright for us to see it; and if it flies over head at night, then the station is in the shadow of the Earth, and so we can't see any reflected sunlight.

For the next week, we are lucky - on some nights we can see the ISS fly overhead on two consecutive orbits, one 96 minutes after the other.

Date	Starts			Maximum height			Ends
	Time	Alt.	Az.	Time	Alt.	Az.	Time	Alt.	Az.
5 May	21:01:04	10	W	21:04:00	86	NW	21:07:00	10	E
5 May	22:36:23	10	W	22:39:22	82	N	22:40:16	41	E
6 May	21:26:09	10	W	21:29:07	73	N	21:32:05	10	E
6 May	23:01:26	10	WNW	23:04:09	62	SW	23:04:09	62	SW
7 May	21:51:11	10	W	21:54:10	83	N	21:56:30	15	E
8 May	20:40:53	10	W	20:43:51	73	N	20:46:49	10	E
8 May	22:16:10	10	W	22:19:07	63	SSW	22:20:18	31	SE
9 May	21:05:51	10	W	21:08:49	85	N	21:11:47	10	E
9 May	22:41:13	10	W	22:43:54	32	SSW	22:44:03	32	SSW
10 May	21:30:45	10	W	21:33:41	61	SSW	21:36:19	12	ESE
11 May	21:55:44	10	W	21:58:24	31	SSW	22:00:02	18	SSE
13 May	21:10:07	10	W	21:12:45	29	SSW	21:15:22	10	SSE

International Space Station flying over the UK...

Over the next few weeks, the International Space Station can be easily seen flying over the UK. Its solar panels are the size of a football field, allowing the space station to be easily seen from the ground as they reflect plenty of sunlight.

Times when the space station can be seen for the next week are below, or at either SpaceWeather.com, or on Heavens-Above.com. Although these times are exact for Brighton, the times will be within half a minute of these times for anywhere in the UK, or you can simply follow those links and type in a new location.

The table below gives the time and position of the International Space Station as it starts to fly over the UK, reaches the maximum height and the time when it disappears (ends).

In the table, Alt. refers to the altitude of the space craft as it flies overhead (90° is directly overhead, and 0° is the horizon); Az. is the Azimuth, or direction, of where it will be at the given time (0° being North, 90°: is East, 180° is South and 270° is West).

Date	Starts			Max. height			Ends
	Time	Alt.	Az.	Time	Alt.	Az.	Time	Alt.	Az.
29 Apr	21:41:07	10	SSW	21:43:40	26	SSE	21:44:24	23	ESE
30 Apr	22:05:51	10	SW	22:08:45	53	SSE	22:09:58	29	E
1 May	20:56:20	10	SSW	20:58:54	27	SSE	21:01:30	10	E
1 May	22:30:59	10	WSW	22:33:57	89	SSE	22:34:54	40	ENE
2 May	21:21:03	10	WSW	21:23:57	55	SSE	21:26:52	10	E
2 May	22:56:14	10	W	22:59:12	73	N	22:59:26	67	NE
3 May	21:46:08	10	WSW	21:49:07	89	N	21:52:05	10	ENE
3 May	23:21:28	10	W	23:23:44	48	WNW	23:23:44	48	WNW
4 May	20:36:08	10	WSW	20:39:03	58	SSE	20:41:59	10	E
4 May	22:11:21	10	W	22:14:19	73	N	22:16:22	18	E
5 May	21:01:12	10	W	21:04:11	87	N	21:07:08	10	E
5 May	22:36:31	10	W	22:39:30	82	N	22:40:24	41	E
6 May	21:26:22	10	W	21:29:20	73	N	21:32:17	10	E
6 May	23:01:39	10	WNW	23:04:22	61	SW	23:04:22	61	SW

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.

5 Years of Swift

Gamma Ray Bursts are know to be the biggest bangs since the big bang! And NASA's Swift space telescope celebrated 5 years of observing these bursts just a few days ago - it was launched on November the 20th, 2004.

And as with most space telescopes, British astronomers play a key role.

Scientists at the University of Leicester designed the X-ray telescope on-board, built the X-ray camera's, and continue to calibrate and monitor its health. Leicester also hosts the UK Swift Science Data Centre. The Mullard Space Science Laboratory, part of the University College London, helped build the Ultra-violet and optical telescope.

UK scientists at both Leicester and MSSL are also on call throughout the day and night for when a burst goes off, to assess whether to follow up the observation with larger ground-based telescopes. Such decisions need to be made within minutes. A full list of UK-based scientists involved in the Swift Space Telescope can be found here on Swift's UK website.

The key thing about Swift is that it is, well, swift! Swift can detect a burst of gamma-rays occurring in about a quarter of the entire sky, and then automatically and rapidly (within 30 seconds!) turn around to scrutinise the rapidly fading explosion with its other on-board telescopes (the X-ray and optical telescopes).

There are two types of gamma-ray bursts - short bursts that last on average about 0.3 seconds, and the long bursts that on-average last about 30 seconds.

Before Swift, scientists knew very little about the short bursts (for obvious reasons... they happened too quickly!), and Swift was the first telescope to discover where these quick explosions were coming from. While scientists are still unsure as to what causes them, the leading idea is that they originate from the mergers of binary neutron stars.

The longer bursts are usually seen to occur with a supernova, which unambiguously links long bursts to the deaths of massive stars... although, strangely, some relatively nearby long bursts appear to have no accompanying supernova. As is often the case in science, when one mystery is solved, another appears!

And because these burst of gamma-rays are the biggest explosions known to man, we can see very distant bursts. The most distant object known, the red object pictured here, is a Gamma-ray burst seen by Swift (see this BBC News story).