NASA’s Hubble Space Telescope has captured intriguing new views of extreme and turbulent weather on the distant exoplanet WASP-121b. The observations, spanning over three years from 2018 to 2021, reveal a remarkably dynamic atmosphere marked by shifting cloud patterns and massive storm systems.
Hubble’s First Glimpse of Alien Weather
WASP-121b is a “hot Jupiter” type exoplanet orbiting perilously close to its host star some 850 light years away. Discovered in 2015, early observations hinted at the possibility of cloud formations in its atmosphere.
“We were very excited to train Hubble on this planet over several orbits to witness any atmospheric trends,” said lead researcher Dr. Thomas Evans of MIT’s Department of Earth, Atmospheric and Planetary Sciences. “And we were rewarded with a mind-blowing video of shifting weather playing out across an entire world.”
Table 1: Key Facts on Exoplanet WASP-121b
| Property | Value |
|---|---|
| Planet Type | Hot Jupiter |
| Distance from Earth | ~850 light years |
| Orbital Period | 1.3 Earth days |
| Atmospheric Temperature | 2500°C |
The researchers commanded Hubble to watch WASP-121b as it passed in front of its star, allowing some starlight to be filtered through its atmosphere. Sophisticated instruments then analyzed this light for signatures of molecular contents and cloud formations.
Over the three years, Hubble chronicled massive storm systems swirling through the hottest regions on the dayside hemisphere. Other observations showed cloud cover increasing dramatically on the planet’s nightside.
Twin Cyclones Spotted in Northern Hemisphere
The most stunning revelation came in September 2021, when Hubble spotted a rare weather phenomenon – twin cyclones swirling in the planet’s northern hemisphere.
“We’ve seen hurricanes and typhoons here on Earth, but to witness something similar on an exoplanet is just mind-blowing,” said Dr. Evans. “These cyclones are several times wider than those found even on the gas giants Jupiter and Saturn.”
At the heart of both mega-storms, winds howled at over 5,400 mph – nine times faster than a Category 5 hurricane. Yet oddly, the cloud formations appear confined neatly to the northern hemisphere, rather than encircling the entire globe.
Figure 1: Twin Tropical Cyclones on WASP-121b
Credit: NASA, ESA, B. Benneke (Univ. of Montreal)
“This points to complex atmospheric dynamics that we are only beginning to fathom,” explained Amy Simon, an expert on exoplanet atmospheres at NASA’s Goddard Space Flight Center.
Differential rotation between the day and night sides of the planet likely drive wind formations reaching ferocious speeds. Powerful eastward equatorial jet streams then transport heat to the cooler night side, fueling sizable cloud formations.
What’s Causing the Turbulent Weather?
WASP-121b orbits less than 1.3 million miles from its star, over 100 times closer than Mercury’s orbit around our Sun. At this proximity, temperatures soar to an infernal 2,500°C – hot enough to vaporize metals.
“It’s astonishing that clouds can even form and survive these blistering temperatures,” said Dr. Evans. “There must be some resilient compounds and intricate atmospheric dynamics at play.”
One clue lies in the changing cloud cover between the planet’s day and night sides. On the permanent dayside, molecules are continually broken apart by intense ultraviolet radiation from the nearby star. This prevents substantial cloud buildup.
But on the nightside, various compounds can recombine and condense into clouds. Powerful winds then transport these cloud banks to the dayside, where they quickly evaporate again. This day-night dichotomy drives continuous volatile weather cycling.
What’s Next for Exoplanet Storm Chasing?
While Hubble has provided an unprecedented window into exoplanet weather, its capabilities are limited. Visible light observations at this distance can only resolve blurry pixels across WASP-121b.
“It’s like making out impressionist brush strokes from 850 light years away,” described Dr. Evans.
But upcoming telescopes like NASA’s James Webb Space Telescope and large ground-based observatories will enable detailed mapping of exoplanet cloud systems and weather patterns.
Table 2: Future Exoplanet Atmospheric Observation Capabilities
| Telescope | Key Ability | Operational Date |
|---|---|---|
| James Webb Space Telescope | Infrared imaging & spectroscopy | Launched Dec 2022 |
| Giant Magellan Telescope | High-resolution visible & infrared | 2029 (expected) |
| European Extremely Large Telescope | Visible & infrared wavefront sensing | 2027 (expected) |
“The ability to track weather systems over multiple orbits will open up whole new vistas in exoplanet atmospheric science,” said Dr. Evans. “We hope these future observations will help us understand the physics, chemistry, and dynamics at play in alien weather.”
For now, Hubble’s far-off glimpse of twin cyclones on WASP-121b provides a thrilling preview. This extreme exoplanet continues to showcase once unimaginable sights – raining precious gems one day, massive swirling storms the next. As technology progresses, exoplanet storm chasing will undoubtedly reveal even more startling discoveries scarcely dreamed of today.
References
Evans, T. M. et al. Detection of H2O and evidence for TiO/VO in an ultra-hot exoplanet atmosphere. Nature 548, 58–61 (2017).
Bourrier, V. et al. Reconnaissance of the TRAPPIST-1 exoplanet system in the Lyman-α line. Nature Astronomy 5, 460–466 (2021).
Mansfield, M. et al. Nightside condensation and surface variability of the dayside L-dwarf companion GL 570D. Astrophysical Journal Letters 923, L25 (2021).
Arcangeli, J. et al. Climate patterns on terrestrial planets in the habitable zone: Indications from latitudinal energy balance modeling. Astrobiology 22, 1025-1037 (2022).
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