Astronomy has a way of confronting you with cosmic head-scratchers that defy all logic. Such is the case with the newly discovered planet Wasp-18. It is 330 light-years away, which is close enough to be considered our neighbor. What’s the problem? It orbits its host star in less than an Earth day, which is so incredibly fast it makes your head spin. By comparison, it takes Earth 365 days to circle Sun. But that isn’t the only thing unusual about Wasp-18. It gets stranger:
From the L.A. Times:
Of the more than 370 exoplanets — planets orbiting stars other than our sun — discovered so far, this is just the second with such a close orbit.
The problem is that a planet that close should be consumed by its parent star in less than a million years, say the authors at Keele University in Britain. The star Wasp-18 is believed to be about a billion years old, and because stars and the planets around them are thought to form at the same time, Wasp-18b should have been reduced to cinders ages ago.
“This planet should spiral inwards on such a short time scale that the likelihood of seeing it is very low,” said Coel Hellier, an astrophysicist at Keele.
“That’s a paradox,” said Douglas P. Hamilton, an astronomer at the University of Maryland who wrote a commentary accompanying the report. He said there were a variety of possible explanations, none of them very satisfactory.
“It’s like going to the scene of the crime and not finding the weapon,” he said. “Something’s happened, but a key piece of evidence is missing.”
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