James Webb reveals a strange bulge in an alien planet's atmosphere

Astronomers using the James Webb Space Telescope have discovered that a distant alien planet’s atmosphere is surprisingly lopsided. Located 1,300 light-years away, the scorching gas giant WASP-17b experiences powerful winds that redistribute heat, causing one side of its atmosphere to bulge outward. A groundbreaking new mapping technique revealed these hidden distortions, confirming predictions about how extreme temperatures and winds shape alien worlds.

James Webb reveals a strange bulge in an alien planet’s atmosphere. The planet has a broad, banded jet around the equator with vast wind speeds that transport material and heat from the permanently irradiated dayside to the permanently shadowed nightside. The atmosphere over the equator of the evening limb (left) is hot as it is transported from the dayside of the planet, while the atmosphere on the right has cooled as it traversed the nightside and passes back to the dayside via the morning limb.

Alderson and her team measured the shape of this transmitting limb as a function of angle across the poles of the planet for the first time. But new observations reveal that the atmospheres surrounding some of these scorching alien worlds can have surprisingly uneven shapes. Using NASA’s James Webb Space Telescope (JWST), researchers have discovered that the atmosphere of WASP-17b, a giant planet roughly 1,300 light-years from Earth, extends farther outward on one side than the other.