• last year
Thus far astronomers have identified more than 5,000 exoplanets, but among all of those, most seem to be either super-Earths or sub-Neptune sized. Now, after observing several planets that have been shrinking, experts believe they might finally know why that might be the case.
Transcript
00:00 Thus far, astronomers have identified more than 5,000 exoplanets, but among all of those,
00:08 most seem to be either super-Earths or sub-Neptune sized, meaning they are almost all at least
00:13 1.6 times the diameter of our planet or upwards of 2 to 4 times the size, with little in between.
00:19 Now, after observing several exoplanets that have been shrinking, experts believe they
00:23 might finally know why that's the case.
00:26 According to a recent release by the NASA Exoplanet Archive, "Exoplanet scientists
00:30 have enough data now to say that this gap is not a fluke.
00:33 There's something going on that impedes planets from reaching and/or staying at this size."
00:38 They say that sub-Neptunes are likely shrinking due to radiation from its planetary core,
00:42 which pushes its atmosphere away until it's around the size of a super-Earth.
00:46 They're calling the process core-powered mass loss, and they believe that the atmosphere
00:49 of the planet is literally lost to space during the process.
00:52 This is in contrast to previous theories which suggested that the planet's host star dissipated
00:57 the atmosphere of an exoplanet.
00:59 Though this process, called photoevaporation, is believed to only occur for around the first
01:03 100 million years of a planet's life cycle, meaning older planets like the ones observed
01:07 in this study would need another avenue for their planetary shrinkage.
01:11 [music]

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