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SEPTEMBER-OCTOBER 2017
SPACE CHRONICLES
T
his is an artist’s impression of the gas giant exoplanet WASP-121b. The bloated planet is so close to its star that the
tidal pull of the star stretches it into an egg shape. The top of the planet’s atmosphere is heated to a blazing 4,600
degrees Fahrenheit (2,500 degrees Celsius), hot enough to boil iron. This is the first planet outside our solar system
where astronomers have found the strongest evidence yet for a stratosphere — a layer of atmosphere in which tempera-
ture increases with higher altitudes. The planet is about 900 light-years away. [Illustration: NASA, ESA, and G. Bacon
(STScI) - Science: NASA, ESA, and T. Evans (University of Exeter)]