WASP-17b

[5] On 3 December 2013, scientists working with the Hubble Space Telescope reported detecting water in the exoplanet's atmosphere.

[8][9] A team of researchers led by David Anderson of Keele University in Staffordshire, England, discovered the gas giant, which is about 1,000 light-years (310 parsecs) from Earth, by observing it transiting its host star WASP-17.

Due to the involvement of the Wide Angle Search for Planets (SuperWASP) consortium of universities, the exoplanet, as the 17th found to date by this group, was given its present name.

[1] Careful examination of the Doppler shifts during transits also allowed them to determine the direction of the planet's orbital motion relative to its parent star's rotation via the Rossiter–McLaughlin effect.

Theories include a gravitational slingshot resulting from a near-collision with another planet, or the intervention of a smaller planet-like body working to gradually change WASP-17b's orbit by tilting it via the Kozai mechanism.

The unusually low density is thought to be a consequence of a combination of the planet's orbital eccentricity and its proximity to its parent star (less than one seventh of the distance between Mercury and the Sun), leading to tidal flexing and heating of its interior.

Size comparison of Jupiter with Ditsö̀
Comparison of " hot Jupiter " exoplanets (artist concept)

From top left to lower right: WASP-12b , WASP-6b , WASP-31b , WASP-39b , HD 189733 b , HAT-P-12b , WASP-17b, WASP-19b , HAT-P-1b and HD 209458 b
This is a transmission spectrum of the hot gas giant exoplanet WASP-17 b captured by Webb's Mid-Infrared Instrument (MIRI) on 12–13 March 2023. It reveals the first evidence for quartz (crystalline silica, SiO 2 ) in the clouds of an exoplanet. [ 19 ]