On the night of 10 June earlier this year, astronomer Anthony Wesley was observing Jupiter when something unusual happened. Using a 37cm (15 inch) telescope fitted with a red filter and a monochrome video camera, Wesley captured a sudden impact on the Jovian surface. This brightened suddenly and then dimmed less than two seconds later.

Wesley is based in Murrumbateman, a small town outside Canberra in Australia, but unknown to him, he wasn’t the only one watching Jupiter that night. Some 5,500 kilometres away in the Philippines, Carlos Go was recording the same event with a 28 cm (11 inch) scope fitted with a blue filter and video camera.

Together these observations provide unambiguous evidence that something hit Jupiter that night (rather than flashed across the Earth’s atmosphere for example). A straightforward analysis of the images indicates the object was small: no more than 13 metres across and weighing less than 2,000 tonnes, says Ricardo Hueso at the Universidad del País Vasco and an international team of buddies.

This size of lump hits Earth every few years or so and generates minor excitement but nothing like it had ever been seen hitting Jupiter. The few other impacts recorded from Earth have all been many orders or magnitude larger (and a shooting star in Jupiter’s atmosphere recorded by Voyager 1 was several orders of magnitude smaller).

As news of the impact spread, professional astronomers began reaching for their lens clothes. Within a few hours, the world’s largest telescopes were all pointed that way: Keck in Hawaii, the Very Large Telescope in Chile, even Hubble had a peak a few days later looking for spectroscopic signs of the meteor’s makeup.

None of them saw anything. Whatever it was that hit Jupiter that night, it was so small that it disappeared without a trace.

That explains why an event like this is new to astronomy. Big professional scopes simply don’t have time to record what goes on in Jupiter’s atmosphere continuously and amateurs have never been able to record and store such data.

That has changed in recent years as the price of memory has fallen and the cost of highly sensitive video cameras dropped. All of a sudden, amateurs are capable of taking on this task. Indeed, while Hueso and co were writing their paper a different pair of astronomers recorded another impact on Jupiter in August.

This kind of data is important for astronomers trying to nail down how likely these kinds of impacts are on the gas giants. It may even may allow a better quantification of the threat to Earth, say Hueso and co.

All that means there is likely to be surge of enthusiastic amateurs pointing their scopes towards Jupiter and Saturn in the hope of spotting more impacts. A more fruitful option, in the short term at least, might be to search through whatever video footage they’ve taken of these planets until now.

These guys might also ask themselves what other kind of rapidly changing astronomical events they might have been missing. Who knows what else a judiciously pointed video camera might reveal.

Time to dust off that old Celestron in the attic.

Ref: arxiv.org/abs/1009.1824: First Earth-based Detection of a Superbolide on Jupiter