Chapter 1: An Overview of WASP-121b

WASP-121b, a tidally locked hot Jupiter, features a striking atmosphere characterized by extreme temperatures. On one hemisphere, temperatures soar to around 3000 degrees Celsius, intense enough to decompose water molecules, resulting in precipitation of rubies and sapphires.

This artist's rendition illustrates WASP-121b, a member of the hot Jupiter classification. Due to its close orbit to its star, this planet is tidally locked, causing one hemisphere to perpetually face the star, while the opposite side remains shrouded in the cold of space. The temperature disparity leads to a significant variation, with the night side being 1500 degrees Celsius cooler. CREDIT: Patricia Klein and MPIA

Once a planet is discovered, scientists are eager to uncover every detail about it. Recently, the focus has expanded beyond merely assessing mass and density to include an in-depth exploration of distant atmospheres. Prior to the launch of a cutting-edge telescope, researchers utilized existing instruments to study the clouds of exoplanets. Their efforts have yielded remarkable insights, particularly into the nightside of WASP-121b, which has been extensively analyzed.

Discovered in 2015, WASP-121b lies approximately 855 light-years from our solar system, boasting a mass that is 20% greater than that of Jupiter and a size nearly twice as large. Its rapid orbit around its star lasts only 30 hours, ensuring that one side remains in constant daylight while the other remains dark. This unique arrangement permits scientists to observe the dayside before the planet rotates out of view.

In a recent publication in Nature Astronomy, researchers compiled data from both hemispheres of WASP-121b to study its atmosphere as a cohesive system. Co-author David Sing elaborates: "We obtained spectra from Hubble during two complete revolutions of the planet to analyze its entire surface."

The findings were fascinating. The upper atmosphere of WASP-121b can reach sweltering temperatures of up to 3000 degrees Celsius on the dayside, causing water molecules to glow and break apart. Conversely, on the night side, temperatures drop to 1500 degrees Celsius, resulting in powerful winds that transport the glowing, fragmented water molecules to the cooler region. As the atmosphere cools, hydrogen and oxygen can recombine to form water vapor, which is then carried back to the hotter dayside, creating a continuous cycle.

However, the conditions prevent the water vapor from forming clouds large enough to produce rain. So, what else is present in this atmosphere? Various metals, including iron, magnesium, chromium, and vanadium, can condense into clouds on the night side, potentially leading to a unique phenomenon where it rains liquid gems such as rubies and sapphires. Yes, it is indeed a rain of gemstones!

Next, the research team aims to secure time on the upcoming telescope, which has yet to begin collecting scientific data.

More Information

MPIA press release

“Diurnal variations in the stratosphere of the ultrahot giant exoplanet WASP-121b,” Thomas Mikal-Evans et al., 2022 February 21, Nature Astronomy

This article is part of the Daily Space podcast/YouTube series. For additional updates from myself, Dr. Pamela Gay, and Erik Madaus, please visit DailySpace.org.

Chapter 2: Insights from Recent Research

To further understand the atmospheric dynamics of WASP-121b, researchers have produced valuable insights.

The first video, titled "Hot Jupiters, Super Puffs, & Lava Planets, Oh My! Exoplanet Science in JWST Year 1," explores the fascinating findings about exoplanets, including WASP-121b.

The second video, "What are hot Jupiters and why do we study them?" delves into the significance of studying planets like WASP-121b and their intriguing characteristics.