Astronomers have spotted a brand-new meteor shower in the night skies of the southern hemisphere. The flurries of shooting stars occurred as Earth passed through streams of dusty material scattered across space by the comet 15P/Finlay. Studies of the celestial show – which astronomers have dubbed the Arid meteor shower, since it appeared to streak from the constellation Ara – could give researchers insights into the make-up of the comet.
Scientists have been routinely observing 15P/Finlay since it was first discovered in 1886. In recent years, a number of independent analyses indicated that our planet would, in 2021, sweep through dense dust clouds left by the comet as it drifted through the inner solar system in 1995, 2008 and 2014. No one knew for certain, though, if the predictions would translate into visible meteors.
To find out, observers across South America – which was well-placed to see the meteors – were put on alert as the nights of anticipated activity approached, in late September and early October. Some researchers even deployed teams with specialist meteor cameras to remote locations in Chile.
The fact that multiple groups were able to successfully observe the meteors, at the predicted times, has thrilled meteor scientists. “I’ve been working on this topic for 20 years, [this is] the first time I’ve seen the birth of a new meteor shower,” says Jérémie Vaubaillon at L’Observatoire de Paris, one of the researchers who made predictions about the meteor activity.
Researchers haven’t yet calculated whether the Arids will appear again in the future, but the 2021 event will have given astronomers valuable data to pore over.
Ye Quanzhi at the University of Maryland, who also modelled the dust streams from comet 15P/Finlay, likens the meteors to sample-return missions – where instead of sending a spacecraft to collect samples, they come to us. “Comets are a loose collection of dust and ice, so by studying the meteoroids as they enter Earth’s atmosphere we learn something about the building block of the comets,” he says.
In particular, Ye wants to investigate the size distribution of the flecks of dust left by the comet. This is essentially a measure of how many large particles there are compared with smaller ones, and it can be calculated by looking at the amounts of bright and faint meteors detected during the Arid shower.
“The size distribution of the dust is an observable that is relatively easy to measure, and it provides clues on how the small cometary grains are glued together,” he says.
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