Did you see it? Plenty of UK-based stargazers did; a huge, bright, long-lasting fireball streaked through the sky last night, 21 September, at 2255BST (2155UT).
The fireball was caught on meteorlog’s meteor cam
I saw it as I was driving home from a stargazing trip to Loch Tay in the Highlands of Scotland. The first glimpse I caught was behind some trees, and I clearly saw the very bright (estimated magnitude -5), yellow fragments of a space rock that was disintegrating as it burned up in our atmosphere. It was traveling westwards from the SW, and look to be about 40° above the horizon. I lost sight of it as I drove, but once I’d turned a bend in the road, a full ten seconds later, I caught the last few fragments burning it.
Straight away I pulled over and tweeted to see if anyone else had seen in, and very soon a flood of observations came in. The team at the Kielder Observatory actually had a group of people up observing, who all saw it.
Huge fire ball from east at 9.55 UTC heading west mag -6 to -7—
Kielder Observatory (@kielder_obs) September 21, 2012
Mike Alexander, who runs the Galloway Astronomy Centre, had a group of guests out stargazing then too, and they also saw it, but even better they heard it!
GallowayAstro (@Gallowayastro) September 22, 2012
By the time I got home, around 0030BST this morning, only an hour and a half after it happened, there were reports of it on BBC Radio 4, with people all over the northern UK and Ireland reporting the same thing, a disintegrating fireball burning through the night sky for around 20 or 30 seconds.
By the time I woke up this morning it had made it onto BBC News.
So what was it?
A few people suggested that it might have been man-made space debris, an old satellite burning up as it de-orbits, but this isn’t the case, for a couple of reasons. First it was traveling east to west, and satellites don’t orbit in that direction. Secondly, Mike (above) reported hearing a sonic boom approx 150 seconds after it faded. Both of these observations point to the fact that it was a large chunk of space rock, a meteor. When meteors are as bright as this one we call them fireballs.
Over the next couple of months ESA’s Cluster spacecraft are going to get very close to Earth, with the orbit of one of the four satellites dropping as low as 200-300km from the Earth’s surface. This is low enough that you may indeed be able to spot – and if you’re skilled enough, take pictures of – the spacecraft.
The four satellites – named Rumba, Salsa, Samba and Tango – were launched in 2000 to study the interaction between the Earth’s magnetic field and the Sun’s solar wind, and because there are four of these satellites, orbiting Earth in a tetrahedral configuration (i.e. one satellite at each of the apexes of a triangular pyramid) the Earth’s magnetosphere can be mapped in 3D.
During June and July 2011 one of the Satellites, Cluster II (Salsa), will come within 200-300km of the surface of the Earth, which means there is a chance you might see it.
They might not be visible from the UK – in fact the British Astronomical Association suggest that the best chance of seeing these satellites is from latitude 20-30 N, so for anyone holidaying in the Canary Islands this summer there’s a chance you’ll catch a glimpse. There is a chance they’ll be visible further north too, from Europe. In any event, the brightness of the satellites is unknown at this stage, and so we can’t tell how easy it will be to spot, even if it’s visible from where you are.
The best way of checking whether the satellites are visible from where you are is to use the excellent Heavens Above website. Enter your observing location and then under “Satellites” click “select another satellite”, then in the “Satellite Name” box type “Cluster%” (the % is important). You can then select each of the four Cluster satellites and in the upper right corner of the information panel you can click “Passes (visible)” to see if there are any passes worth watching for from your location.
This will give you five crucial bits of information:
- date of passes
- magnitude (brightness) of the satellite (it is currently showing ?)
- the time, altitude, and direction of when the visible pass starts
- the time, altitude, and direction of when the satellite at its highest in the sky
- the time, altitude, and direction of when the visible pass ends
ESA have even announced a competition on Facebook, where they are encouraging people to try and image the satellites! This is no mean feat, but not without precedent. In fact a number of very experienced astrophotographers have caught images of the International Space Station as it orbits about 360km overhead. One of my favourites is this one by Thierry Legault, of the space shuttle Atlantis approaching the International Space Station where both were silhouetted in front of the Sun.
Happy satellites hunting, and let me know if you catch a glimpse!
(HT to the BAA for bringing this to my attention).