Hubble Checks the Weather on Hot Jupiters. Forecast: 100% Chance of Hellish Conditions

While the Hubble Space Telescope celebrates 32 years in orbit, like a fine wine, it has only gotten better with age as it continues to study the Universe and teach us more about our place in the cosmos. Hubble doesn’t just take breathtaking images of our Universe, but it also studies our own solar system, galaxies, and exoplanets, as well. It is this last subject where Hubble has recently been hard at work, though.

In two papers published in Nature and Astrophysical Journal Letters, teams of Hubble astronomers are reporting on bizarre weather conditions on two sizzling worlds known as hot Jupiters, WASP-178b and KELT-20b. The Nature study describes raining vaporized rock on WASP-178b, while the Astrophysical Journal Letters study discusses how KELT-20b has its upper atmosphere getting hotter rather than cooler because it is being “sunburned” by intense ultraviolet (UV) radiation from its star.

An artist’s impression of the ultra-hot Jupiter KELT-20b. (Credit: NASA/ESA/Leah Hustak, Space Telescope Science Institute)

“We still don’t have a good understanding of weather in different planetary environments,” said David Sing of the Johns Hopkins University in Baltimore, Maryland, and co-author on both studies. “When you look at Earth, all our weather predictions are still finely tuned to what we can measure. But when you go to a distant exoplanet, you have limited predictive powers because you haven’t built a general theory about how everything in an atmosphere goes together and responds to extreme conditions. Even though you know the basic chemistry and physics, you don’t know how it’s going to manifest in complex ways.”

WASP-178b is located about 1,300 light-years from Earth. On the daytime side the atmosphere is cloudless and is enriched in silicon monoxide gas. Because one side of the planet permanently faces its star, the torrid atmosphere whips around to the nighttime side at super-hurricane speeds exceeding 2,000 miles per hour. On the dark side, the silicon monoxide may cool enough to condense into rock that rains out of clouds, but even at dawn and dusk, the planet is hot enough to vaporize rock. “We knew we had seen something really interesting with this silicon monoxide feature,” said Josh Lothringer of the Utah Valley University in Orem, Utah, and lead author on the Nature study.

Though super-hot Jupiters are uninhabitable, this kind of research helps pave the way to better understanding the atmospheres of potentially inhabitable terrestrial planets. “If we can’t figure out what’s happening on super-hot Jupiters where we have reliable solid observational data, we’re not going to have a chance to figure out what’s happening in weaker spectra from observing terrestrial exoplanets,” said Lothringer. “This is a test of our techniques that allows us to build a general understanding of physical properties such as cloud formation and atmospheric structure.”

Hot Jupiters

Exoplanets known as hot Jupiters are exactly what their name implies, as they are planets physically similar to Jupiter but instead orbit extremely close to their parent star, often taking only a few days to complete one orbit. As is the case with WASP-178b and KELT-20b, most hot Jupiters endure searing temperatures above 1650°C (3000°F). This is hot enough to vaporize most metals, including titanium, as hot Jupiters possess the hottest planetary atmospheres ever seen. Another unique feature about hot Jupiters is that despite them not existing in our solar system they are quite common in the galaxy, as about one in 10 stars are currently estimated to have a hot Jupiter. Ironically, the first discovery of an exoplanet orbiting a Sun-like star was actually a hot Jupiter, 51 Pegasi b. The first exoplanet discovered was in 1992, as two planet-sized bodies were found to orbit pulsar PSR B1257+12.

An artist’s impression of a hot Jupiter exoplanet. (Credit: C. Carreau/ESA)

Hubble Space Telescope

As stated, Hubble has been in orbit for 32 years and continues to teach us about our place in the cosmos. Launched in 1990 onboard the Space Shuttle Discovery, Hubble was named after American astronomer, Edwin P. Hubble, who discovered the expansion of the Universe in the 1920s. The now-famous telescope bearing the famous astronomer’s name has made more than one million observations since the beginning of its mission. Recently, Hubble imaged the most distant single star ever detected in outer space, a mind-blowing 12.9 billion light-years from Earth.

Hubble as seen from Space Shuttle Discovery during its second servicing mission. (Credit: NASA)

With the recent launch of the James Webb Space Telescope and no scheduled servicing missions for Hubble, the aging telescope’s days in space won’t last forever. While there are estimates that Hubble could last until the end of the decade, Hubble is slowly experiencing software failures, another sign it’s on its last legs. While it’s still functioning, what future discoveries could it unlock about our Universe? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

Sources: NASA (1), ESA Hubble, NASA (2),, NASA (3), Nature (1), Astrophysical Journal Letters, EarthSky, Nature (2), Nature (3), BBC, Smithsonian Magazine, Goddard Space Flight Center, MIT Technology Review