Free Astronomy Magazine September-October 2016

SPACE CHRONICLES gen-helium envelope increases the chances for habitability on these planets,” said team member Nikole Lewis of the Space Telescope Science Institute (STScI) in Baltimore, Mary- land. “If they had a significant hy- drogen-helium envelope, there is no chance that either one of them could potentially support life be- cause the dense at- mosphere would act like a greenhouse.” Julien de Wit of the Massachusetts Insti- tute of Technology in Cambridge, Massa- chusetts, led a team of scientists to ob- serve the planets in near-infrared light using Hubble's Wide Field Camera 3. They used spectroscopy to decode the light and reveal clues to the chemical makeup of an atmosphere. While the content of the atmospheres is unknown and will have to await further observations, the low concentration of hy- drogen and helium has scientists excited about the implica- tions. “These initial Hubble observations First atmospheric study of earth-sized exoplanets by NASA T his illustration and the following video show two Earth-sized worlds passing in front of their parent red dwarf star, which is much smaller and cooler than our sun. The planets, TRAPPIST-1b and TRAPPIST-1c, re- side 40 light-years away. They are be- tween 20 and 100 times closer to their star than Earth is to the sun. Researchers think that at least one of the planets, and possibly both, may be within the star's hab- itable zone, where moderate temperatures could allow for liquid water on the surface. Hubble looked for evidence of extended atmospheres around both planets and didn't find anything. This leaves open the possibility the planets have thinner, denser atmospheres like Earth's. [NASA, ESA, G. Bacon (STScI), J. de Wit (MIT)] U sing NASA's Hubble Space Telescope, astronomers have conducted the first search for atmospheres around temperate, Earth-sized planets beyond our solar system and found indications that increase the chances of habitability on two exoplanets. Specifically, they discovered that the exoplanets TRAPPIST-1b and TRAP- PIST-1c, approximately 40 light-years away, are unlikely to have puffy, hydrogen-dominated atmospheres usually found on gaseous worlds. “The lack of a smothering hydro-