Question 1

True or false: HD 209458 b completes one orbit around its star every 3.5 Earth days.

Accepted Answer

True. HD 209458 b is a hot Jupiter with an orbital period of just 3.52 days, extremely close to its star.

Question 2

True or false: HD 209458 b has a solid, rocky surface like Earth.

Accepted Answer

False. It’s a gas giant with no solid surface, composed mainly of hydrogen and helium.

Question 3

True or false: HD 209458 b's temperature is cooler than any planet in our solar system.

Accepted Answer

False. It's a hot Jupiter with surface temperatures around 1,000°C, far hotter than any solar system planet.

Question 4

True or false: HD 209458 b was the first exoplanet observed to have an atmosphere.

Accepted Answer

True. In 2001, Hubble detected sodium in its atmosphere, marking the first direct detection of an exoplanet's atmosphere.

Question 5

True or false: HD 209458 b was discovered using direct imaging from ground telescopes.

Accepted Answer

False. It was discovered via the transit method in 1999, not direct imaging, which came later for other planets.

Question 6

True or false: HD 209458 b orbits a red dwarf star much smaller than the Sun.

Accepted Answer

False. Its host star, HD 209458, is a G-type star similar to our Sun, not a red dwarf.

Question 7

True or false: HD 209458 b is losing its atmosphere due to intense stellar radiation.

Accepted Answer

True. It's a 'bloated' planet; hydrogen is evaporating at high speed, forming a comet-like tail.

Question 8

True or false: Water vapor has been detected in the atmosphere of HD 209458 b.

Accepted Answer

True. Observations by Hubble and Spitzer space telescopes have confirmed the presence of water vapor in the exoplanet's atmosphere.

HD 209458 b Trivia Questions