NASA/JPL-Caltech/R. Hurt

ScienceShot: Alien World Sports Mysterious Hot Spot

Something strange is a-brewing on upsilon Andromedae b. Astronomers have classified the exoplanet, orbiting a sun-like star about 44 light-years away, as a hot Jupiter—a gas giant circling so close to its parent sun that its atmosphere is boiling away. Like most hot Jupiters, upsilon Andromedae b is also tidally locked to its star, meaning it always shows the star the same face. Such a planet should be hottest smack-dab in the middle of its sun-facing side. Not upsilon Andromedae b. In an upcoming issue of The Astrophysical Journal, astronomers report observations by the heat-seeking instruments aboard the Spitzer Space Telescope, which show the planet's hottest region is located near its twilight zone—the line bisecting the day and night sides. It's possible that supersonic winds, propelled by some interaction between the planet and the star's magnetic field, could be causing the misplaced hotspot. But, for the moment, this cosmic mystery remains unsolved.

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