Pitch Black Planet 'WASP-104b' Absorbs Enough Light to Appear Invisible in Space

Wednesday, 25 April 2018 - 6:32PM
Space
Astronomy
Wednesday, 25 April 2018 - 6:32PM
Pitch Black Planet 'WASP-104b' Absorbs Enough Light to Appear Invisible in Space
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NASA/JPL-Caltech
Thanks to the recent flurry of exoplanet discoveries over the past few years, we've managed to find both similar planets to the ones in our own solar system, and completely bizarre planets that we've never seen before.

Sitting firmly in the "completely bizarre" category is WASP-104b, an exoplanet about 466 lightyears away which orbits a yellow dwarf star (called WASP-104, if you were wondering) inside the Leo constellation. The planet is a difficult one to describe, partly because we have no way to determine what it looks like - it absorbs up tp 97-99 percent of all visible light from its nearby star, making it appear pitch black.

Since it doesn't leave behind any light for us to see it with, we had look for different signs, and it was originally found during a "transit event", when an exoplanet passes in front of its star and causes a small dip in that star's brightness. That's how lots of exoplanets are found, and the recently launched Transiting Exoplanet Survey Satellite (TESS) looks exactly this when hunting for distant planets.

Astronomers first discovered WASP-104b back in 2014, and while they'd noticed it was dark, it was only just recently that a team of researchers led by Teo Mocnik at Keele University in England discovered that this was actually one of the darkest planets ever discovered.



Beyond looking like a black hole that's lost its massive gravity, WASP-104b has a number of other oddities. It's considered a "Hot Jupiter" planet, which means that it's a large gas giant much like Jupiter, but it also orbits extremely close to its star.

In this case, the planet is so close to its star that it can complete a full orbit in only 1.75 days, which makes for a very short year. It's also tidally locked, which means the same side of WASP-104b is always facing its star; this could be what's making the planet so dark, as the side that's always facing an uncomfortably close star couldn't produce clouds or ice, which can be reflective. The atmosphere is also likely to be extremely thick, which would lead to more absorbed light.

While there's a lot we can determine about this planet, what it actually looks like is not one of them. Even with new telescopes like TESS and soon the James Webb Space Telescope, we can only gain so many details about exoplanets that are so vastly far from us.

And when that far off planet is too dark to see, it doesn't help.
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