NASAさんのインスタグラム写真 - (NASAInstagram)「How do you find out if a planet orbiting another star has an atmosphere? In some cases, @webbtelescope has a novel way: looking at how hot the daytime side of the planet is as it passes behind its star. If a rocky exoplanet orbiting a red dwarf star lacks an atmosphere, its dayside would be very hot, just as we see with the Moon or Mercury. The presence of that atmosphere is expected to lower the dayside temperature that Webb would measure. It could do this in two ways. A thick atmosphere could transport heat from the dayside to the nightside through winds. A thinner atmosphere could still host clouds, which reflect a portion of the incoming starlight thereby lowering the temperature of the planet's dayside. https://www.nasa.gov/feature/goddard/2019/astronomers-propose-a-novel-method-of-finding-atmospheres-on-rocky-worlds This artist’s impression shows a rocky exoplanet with a wispy, cloudy atmosphere orbiting a red dwarf star. Astronomers have identified a new method that could allow Webb to detect an exoplanet’s atmosphere in just a few hours of observing time. Credits: L. Hustak and J. Olmsted (STScI)」12月3日 4時08分