Large green meteor streaks across the southern U.K. sky

A large green meteor streaked by over southern England last night, lighting up not only the sky, but also the Twitterverse.

This bright 'fireball' was seen around 9:45 p.m. UTC, as it passed from southeast to northwest, and according to The Independent, it was reported on social media by witnesses from the counties of Cornwall, Hampshire, Lancashire, South Wales and Worcestershire.

[ Related: Halley’s Comet meteor shower peaks ]

The green colour of the meteor indicates that it had some copper content. Other elements that contribute to a meteor's color: sodium produces orange/yellow, iron makes yellow, purple comes from potassium and red meteors have silicate.

Since we are currently passing through the stream of debris left behind by the passage of Halley's Comet, some news agencies are reporting that this was likely an especially large piece of debris from that stream, maybe the size of a baseball. However, whereas that is possible, there are factors that throw some uncertainty over that conclusion.

Although the meteor came from roughly the same direction as the eta Aquarid meteor shower (southeast), the 'radiant' for that shower — the point in the sky where the meteors seem to radiate out from — was well below the horizon, as pointed out by astronomer Pete Lawrence (@Avertedvision):

It's possible that some larger bit of the comet may have ended up drifting further away from the rest of the debris, or got knocked on a different trajectory, and thus entered the atmosphere further west and thus lower in the sky than where the rest of the debris was streaming in.

BBC News reported that Richard Escott, a BBC employee in Cardiff, told them "it was at sort of building level and then died out to nothing."

So, it did appear to some to be fairly low in the sky, it seems. However, the height of a meteor can be very deceptive, and how high it looks is entirely dependent on your perspective. It's the same as how the Moon can look very large near the horizon, but smaller when it's high in the sky.

As Robert Lunsford pointed out on the American Meteorological Society website, back on March 22nd: "Meteors become visible at approximately 50 miles above the Earth’s surface. Friction slows these objects down until they fall below the velocity necessary to produce light. At this point they still lie at least 5 miles high in the sky."

So was this a Halley's Comet meteor? The jury's still out, but I wouldn't put money on it.

(Update: A full report from the UK Meteor Network has concluded that the meteor was a 'sporadic' meteor, and not part of the eta Aquarid meteor shower. Their calculations, based on footage of the event, showed that the meteor was traveling at around 14 km/s (over 50,000 km/h), and it burned out at roughly 28 kilometres above the ground. Thanks to @UKMeteorNetwork for the info!)

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Also, if you're searching around the web for pictures of this meteor, beware of fakes. Two images (top of the page here) that seem to be making the rounds are apparently from the bright fireball that caused a sonic boom over California on October 18, 2012 (originals here and here).

Keep watching the skies, though. These kinds of fireballs happen all the time, even when there's not a major meteor shower happening, but most of them get missed because they happen over very remote areas or people just aren't looking up.

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