Transits
Spectroscopic studies first revealed the presence of a planet around HD 209458 on November 5, 1999. Astronomers had made careful photometric measurements of several stars … See more

In 2014, a magnetic field around HD 209458 b was inferred from the way hydrogen was evaporating from the planet. It is the first (indirect) detection of a magnetic field on … See more

• Charbonneau, D. (2003). "HD 209458 and the Power of the Dark Side". In Deming, Drake; Seager, Sara (eds.). Scientific Frontiers in … See more

In August 2008, the measurement of HD 209458 b's Rossiter–McLaughlin effect and hence spin–orbit angle is −4.4 ± 1.4°.
The study in 2012, updated the spin-orbit angle to −5±7°. See more

Stratosphere and upper clouds
The atmosphere is at a pressure of one bar at an altitude of 1.29 Jupiter radii above the planet's center.
Where the pressure is 33±5 millibars, the atmosphere is clear (probably hydrogen) and its See more

• 51 Pegasi b
• YZ Ceti another extra solar planet with evidence of magnetic fields
• HAT-P-11b another extra solar planet with evidence of … See more

• "European astronomers observe first evaporating planet". Hubble Space Telescope. ESA/NASA. 2003-03-12. Retrieved 2008-06-28.
• Hubble Finds Three Surprisingly Dry Exoplanets See more