|Sightings in 2000|
|Sightings in 2002|
|Sightings in 2003|
The ISS is now bigger than my original alert at the end of 2000 as several Space Shuttle visits have added new modules and solar panels. The orbit remains the same as before, so the sighting details in my original alert still hold true, though the increased size means a greater brightness.
Any of the following websites can give predictions as to when you can see the ISS;;;
A few people have been asking about seeing the new International Space Station and the Daily Telegraph ran an article on 19th Dec. alluding to its presence as a Christmas Star. Certainly it should now be a lot brighter following the addition of solar panels a few weeks ago.
I have therefore done a bit of research and find that, unlike the more usual subject of cosmic updates, this should be an easy object to see at a time that is convenient to everyone. Although of course a clear sky is required, it is less dependent on the weather on any particular day because there will be many opportunities to see it. Indeed, as months and year pass it will get brighter as more modules are added, but it is certainly worth a look for over the festive period so you can be among the first to have seen it.
My research has taken me to the website Lift-Off which runs a program that allows you to track the position of satellites in their orbits around the Earth (J-Track) and make predictions as to what can be seen, and when, from any particular place on the ground (J-Pass). When downloaded it runs as a Java applet in the browser, and is capable of being used offline without the need for a continuous internet connection. You can also request that it sends you e-mails notifying you of the visibility from your chosen location of objects you select, though I haven't tried this yet.
I have run predictions from
various parts of the UK for the next 2 weeks and they say that
the ISS will indeed be visible most evenings until the end of
December. The following ground rules seem to hold true for all
sightings, and will be useful to bear in mind when relating my
predictions to your location.
a) The ISS passes from west to east, rising between south-west and west and setting between east and south-east.
b) The maximum elevation that it can reach in the sky is as follows, as measured upwards from the southern horizon:-
Exeter: 105 degrees (i.e. 15 degrees north of the zenith)
London: 90 (i.e. directly overhead)
Inverness: too low to be reliably seen
It orbits at about 300km altitude with an orbital inclination of 52 degrees, which means that London is about as far north as you can be to see it overhead. As you go further north, so the maximum elevation drops off as you get further from the track of the orbit.
c) The spread of longitude across the UK makes relatively little difference to rising and setting times because of the high speed at which the ISS is travelling, 17,500 mph = 5 miles a second. For example the distance from Exeter to London of 150 miles (3.5 degrees of longitude) is covered in just 30 seconds, so Exeter's timings are typically 30 seconds ahead of London's. However, as you travel north the lower elevation tends to postpone rising times, in the same way as the winter sun rises later than a summer one. The net result is a difference in rising times compared to London (51.5 degrees N, 0 degrees E) typically as follows:-
Exeter (50.7N, -3.5E): 30 seconds early
Manchester (53.5N, -2.0E): 15 early
Edinburgh (56.0N, -4.0E): 30 early
(I have quoted the longitudes as negative numbers because the program expects it to increase in an easterly direction. Alternatively subtract from 360, so for example Edinburgh can be stated as 356 degrees)
d) The time taken from rising to setting for a most favourable pass (i.e. one that achieves as high an elevation as possible for the location) seems to be fairly constant at 10 minutes for all locations. However, given that the ISS will be harder to see at low elevation (because of greater distance, a thicker amount of atmosphere for the light to pass through, and more likely to be obscured by trees, buildings etc) I have calculated the times to reach 30 degrees elevation, and how long it will remain above 30 degrees, as follows:-
|Time from rising to reach 30 degrees||Time above 30 degrees|
|3m 40s||2m 40s|
|3m 40s||2m 40s|
|3m 40s||2m 30s|
|4m 10s||1m 20s|
I have ascertained appearances
of the ISS between now and the end of December as follows, stating
rising time and the maximum elevation from each site. If a second
time is quoted it is when it passes into the Earth's shadow and
you will not be able to follow it all the way to the eastern horizon.
On the basis that nobody will be too inclined to get up early
in the morning I have given evening appearances only.
|December||GMT||Exeter||London||Manchester||Edinburgh||A bit of a dismal record!|
|Fri 22nd||4.30pm||85||80||50||Too low||Cloudy, sky too bright|
|Mon 25th||4.32pm||105||85||55||35||Cloudy, sky too bright|
|Mon 25th||6.07 - 6.13pm||55||40||Too low||Too low||Cloudy|
|Tue 26th||5.04pm||85||60||40||Too low||Cloudy|
|Wed 27th||5.36pm||40||30||Too low||Too low||Saw it for the first time|
|Thu 28th||4.33pm||70||50||35||Too low||Clear, but sky too bright|
|Fri 29th||5.05pm||35||Too low||Too low||Too low||I was too far north|