Life Science Did a Death Star take out a planet for real? Something did
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Did a Death Star take out a planet for real? Something did

In 2008, the Hubble Space Telescope revealed a 'planet' in orbit around the star Fomalhaut. Six years later it was gone. Image: NASA, ESA, UC
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If you’ve felt a great disturbance in the Force of late, of the sort that made you stagger and press your fingertips to your temple, then fair enough.

It seems the famed planet-killing Death Star from Star Wars has been at it again.

What else can explain the fact that a distant planet followed by the Hubble Space Telescope has disappeared from sight?

When astronomers took a closer look, all they found was an immense cloud of dust.

The planet, known as Fomalhaut b, was first photographed by Hubble in 2004.

According to a NASA statement, Fomalhaut b was clearly visible for several years.

The Hubble observations revealed it was a moving dot. It was formally announced as a new planet in 2008.

This was exciting. Fomalhaut b was one of the first planets to be directly imaged by a telescope.

As NASA explains, exoplanets had previously been discovered by indirect detection methods, “such as subtle back-and-forth stellar wobbles, and shadows from planets passing in front of their stars”.

It was a big planet. Only 25 light years from our Solar System.

And its star, Fomalhaut, known as the Lonely Star, is one of the brightest in the night sky.

Some astronomers now say it was never a planet at all.

Instead, they suggest it could be a vast, expanding cloud of dust produced in a collision between two large bodies, probably asteroids.

“These collisions are exceedingly rare and so this is a big deal that we actually get to see one,” said Dr András Gáspár of the University of Arizona, Tucson, in a prepared statement.

“We believe that we were at the right place at the right time to have witnessed such an unlikely event with NASA’s Hubble Space Telescope.”

In other words, what the Hubble saw may have been the immediate aftermath of the impact.

The two asteroids making one clump of debris that over time gradually spread out in such a way that created the illusion of a planet fragmenting to dust.

An artist’s impression of a collision of two icy asteroid-sized bodies orbiting the bright star Fomalhaut, about 25 light years from Earth. Image: NASA

According to NASA, Fomalhaut b was an oddball from the beginning, and didn’t behave quite like other directly imaged planets.

“The object was unusually bright in visible light, but did not have any detectable infra-red heat signature,” NASA said.

“Astronomers conjectured that the added brightness came from a huge shell or ring of dust encircling the planet that may possibly have been collision-related.

“The orbit of Fomalhaut b also appeared unusual, possibly very eccentric.”

The team emphasises “the final nail in the coffin” came in 2014, when Hubble data revealed their planet had vanished.

Earlier images had provided a hint: The planet had appeared to be gradually fading.

“Clearly, Fomalhaut b was doing things a bona fide planet should not be doing,” said Dr Gáspár, co-author of a paper published at the Proceedings of the National Academy of Sciences.

“Clearly, Fomalhaut b was doing things a bona fide planet should not be doing,” Dr Gáspár said.

“Our study, which analysed all available archival Hubble data on Fomalhaut revealed several characteristics that together paint a picture that the planet-sized object may never have existed in the first place.”

NASA says that by now the debris cloud, consisting of “dust particles around one micron (one-50th the diameter of a human hair) is below Hubble’s detection limit. The dust cloud is estimated to have expanded by now to a size larger than the orbit of Earth around our Sun”.