Rubies and sapphires in the form of liquid descend from a cloud of iron and titanium onto a distant incandescent surface. The Jupiter exoplanet WASP-121b is a bright egg-shaped exoplanet that orbits the planet Jupiter approximately 900 light-years away. At times, temperatures might reach up to 2540 degrees Celsius on the everyday side of the planet. It is so hot that heavy metal components such as iron and magnesium exist as gases in the atmosphere and are constantly emitted into space by the sun's rays as they heat up.

A new study, published in the scientific journal Nature Astronomy, describes scientists' first sight at the planet's dark side, which was made possible by NASA's Hubble Space Telescope.

South African Astronomical Observatory telescopes identified WASP-121b in 2015, with the help of the South African Space Agency. WASP-121 is a planet that is somewhat larger and heavier than Jupiter. It lies on the periphery of the gravitational pull of its parent star, which poses the possibility of the planet being torn apart by the same forces that are pulling it apart.

Known as the "glowing Jupiter," it completes one full circuit around the parent star every 1.3 days and is tidally locked with it, which means that one side of it is perpetually bathed in starlight while the other side looks endlessly into darkness into the depths of the universe.

Ben Montet, an astrophysicist at the University of New South Wales who was not involved in the work, describes it as "one of the most severe systems we have ever seen." He observes that his unusually hot day is hotter than the surface of some stars.

Hubble was essential in obtaining further information about the atmosphere of WASP-121b, first identifying in 2017 that it has water vapor and then suggesting that this exoplanet also contains a stratosphere, which is the first time such a discovery has been made in the universe. With the help of Hubble, the new research reveals in great detail the planet's atmosphere and how the shift in temperature from day to night affects the components flying around the upper layers of that dazzling Jupiter.

In 2018, Hubble observed WASP-121b twice, with the first observation occurring in 2018 and the second occurring a year later. Using Hubble's "eye," scientists can collect information about light, which they can then split down into wavelengths that correlate to specific elements and compounds. The scientists looked for water vapor on the night side of WASP-121b and utilized that knowledge to establish how "cool" the dark side of that planet actually is. WASP-121b is a planet orbiting the sun.

They discovered that the temperature on the night side lowers to approximately 1200 degrees Celsius, which is not particularly cold from our perspective, but is extremely frigid when contrasted to the temperature on the day side WASP-121b. It was also possible for them to compute the average wind speed on the planet, which exceeds an unbelievable 17,600 kilometers per hour.

A team of astronomers used this knowledge to simulate what other types of chemicals and compounds might exist in the atmosphere of that exoplanet, and they came up with some interesting results.

They observed that the night side is likely to include unusual clouds of iron and titanium, as well as corundum, the same mineral that may be found in rubies and sapphires on the surface of the planet. Located in a highly hostile environment, these clouds condense precipitation, resulting in precipitation-related phenomena like rain.

Montet points out that all of these unusual substances are released into the sky as rain by the planet's atmosphere. On the surface, it appears like if we manage to survive the conditions on WASP-121b, we will witness the current generation of rubies and sapphires descending from the sky.

WASP-121b is also likely to be observed later this year by NASA's James Webb Space Telescope, which was recently launched. With the telescope, scientists will be able to observe the planet in infrared radiation and examine its atmospheric chemistry, providing them with a greater understanding of how hot Jupiters form and what exactly makes up the planet's atmosphere.