5 of the Strangest and Most Dangerous Exoplanets Ever Discovered

Long before astronomers discovered the first exoplanet in 1992, the idea of worlds orbiting distant stars captivated the minds of academics and dreamers alike. As far back as the 16th century, philosopher Giordano Bruno speculated about an infinite universe filled with countless stars, each surrounded by its own planets.

Today, with more than 5,800 confirmed exoplanets, astronomers are finding that some of these worlds are astonishingly strange, defying even the wildest predictions.

Some exoplanets rain molten iron, others are largely composed of diamond. Some worlds orbit two suns — and some orbit no star at all. From boiling-hot gas giants to worlds with bizarre weather patterns, here are five of the weirdest exoplanets scientists have discovered so far.

Imagine a world where the weather forecast includes showers of molten iron. WASP-76 b, located roughly 640 light-years from Earth, is a gas giant that orbits its star so closely that its dayside reaches blistering temperatures of around 4,350 degrees Fahrenheit (2,400 degrees Celsius). And at such extreme heat, metals like iron turn to vapor.

Because the planet is tidally locked, one side of WASP-76 b permanently faces its star while the other remains in eternal darkness. Powerful winds whip the vaporized iron from the scorching dayside to the much, much cooler nightside, where it condenses and falls as molten iron rain. This unique atmospheric process makes WASP-76 b a top contender for one of the most hellish exoplanets ever discovered.

Read More: 6 Exoplanets in our Universe That Could Support Life Other Than Earth

If WASP-76b sounds dangerous, HD 189733 b might be even more nightmarish. Located about 64 light-years away, this gas giant is a deep azure blue, much like Earth. But don’t let its color fool you — this world is anything but hospitable.

HD 189733 b experiences devastating storms with winds that reach 5,400 mph (8,700 km/h) – more than 20 times faster than the winds of the strongest cyclone ever recorded on Earth.

But what really sets the planet apart is its rain. Instead of water, silicate particles in the upper atmosphere condense into molten glass, which then pelts the planet in a sideways onslaught, thanks to its intense winds. The deep blue hue of the planet is due to the way these silicate clouds scatter blue light.

Science fiction fans have long dreamed of planets with two suns. And Kepler-16 b, located roughly 250 light-years away, is the real deal. Discovered in 2011, this exoplanet defies the traditional solitary planetary orbit by circling two stars — much like the fictional Tatooine from Star Wars.

Despite its cinematic allure, Kepler-16b presents a harsh and frigid environment, with surface temperatures averaging around negative 100 degrees Fahrenheit to negative 150 degrees Fahrenheit. The planet is roughly comparable to Saturn in mass and size, but Kepler-16b's location and conditions offer little prospect for habitability.

Confirmed in 2023, WASP-193 b is one of the lightest, fluffiest planets ever observed. Roughly 1.5 times the diameter of Jupiter but containing only 14 percent of the mass, this gas giant has an incredibly low density, earning it the nickname "cotton candy planet."

The planet’s airy composition remains a mystery. But scientists suspect that its bloated atmosphere, composed primarily of hydrogen and helium, may be the result of intense heating from its parent star, which the world orbits once every 6.2 days.

Nonetheless, its extreme puffiness challenges existing models of planetary and atmospheric formation and structure, making it a prime target for follow-up observations by the James Webb Space Telescope.

Read More: Earth-Sized Exoplanet Found 55 Million Light-years Away From Our Planet

SIMP J01365663+0933473, located approximately 20 light-years from Earth, is a fascinating celestial object that blurs the line between planet and brown dwarf. With an estimated mass of about 12.7 times that of Jupiter, it resides near the threshold where deuterium fusion occurs, the defining process of brown dwarfs. This strange world is free-floating, not bound to any star, and boasts a surface temperature of around 1,500 degrees Fahrenheit.

What further sets SIMP J01365663+0933473 apart is its powerful magnetic field, measured to be some 4 million times stronger than Earth’s. This intense magnetism produces spectacular auroras, detectable through radio emissions, even without the help of a parent star's solar wind. Scientists think one possibility is that the auroras are driven by an orbiting planet or moon interacting with the brown dwarf’s intense magnetic field.

The discovery of thousands of wildly different exoplanets has forever changed our understanding of the cosmos. While our solar system follows certain predictable patterns, the worlds orbiting distant stars continue to defy all expectations. From raining molten glass to orbiting two (or zero) suns, these planets prove that nature can be far stranger than we ever imagined.

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• The Schools' Observatories. The First Discoveries

• NASA. WASP-76 b

• NASA. HD 189733 b

• NASA. 5,400 mph Winds Discovered Hurtling Around Planet Outside Solar System

• NASA. Kepler-16 b

• Cornell University. Kepler-16: A Transiting Circumbinary Planet

• NASA. WASP-193 b

• Nature Astronomy. An extended low-density atmosphere around the Jupiter-sized planet WASP-193 b

• The Astrophysical Journal. The Strongest Magnetic Fields on the Coolest Brown Dwarfs

• National Radio Astronomy Observatory. VLA Detects Possible Extrasolar Planetary-Mass Magnetic Powerhouse

Jake Parks is a freelance writer and editor who specializes in covering science news. He has previously written for Astronomy magazine, Discover Magazine, The Ohio State University, the University of Wisconson-Madison, and more.