Photo by: NASA/ Exoplanet Exploration Program

NASA/ Exoplanet Exploration Program

Meet WASP-127b, the Fluffiest Planet in the Galaxy

Take a planet with the mass of, say, Saturn. You know, pretty big, but not ridiculously big. Just…normal big.

November 15, 2021

Now take that planet and move it closer to its parent star. No, closer. Nope, not close enough. Closer than the Earth orbits around the Sun. Closer than Venus. Yeah, go all the way: move that planet so that it’s less than a quarter of the orbit the Mercury.

An orbit that close is going to make the planet just a little bit hot. Over 2,000 degrees Fahrenheit hot. That’s hotter than any object in the solar system, by far.

That’s WASP-127b, a planet 525 light-years away from us.

WASP-127b is like any other massive planet: it’s made of almost entirely of the gasses hydrogen and helium. And what do gasses do when they get hot? They expand. Like a hot air balloon, WASP-127b has puffed out to become the fluffiest known planet in the galaxy. Despite only having a fraction of the mass of Jupiter, it’s 30% wider than the biggest planet in our solar system.

And like all the other weird exoplanets (planets outside the solar system) out there, the more we study it the weirder it gets.

Recently, a team of astronomers used a combination of instruments, including the Hubble Space Telescope and the ESPRESSO spectrograph at the European Observatory’s Very Large Telescope in Chile.

157308245

Hubble space telescope.

Photo by: jamesbenet

jamesbenet

Hubble space telescope.

They found sodium. The same sodium that’s in your table salt is hanging out in the atmosphere of this alien world, at a much lower altitude than the astronomers expected. Who salted up this puffball and why is anybody’s guess.

And there are clouds. The astronomers found signals of water vapor that appeared in infrared light, but not in visible light. Since the water vapor signal came from deep in the atmosphere, this meant that there was something higher up that screened out visible light but let infrared light pass through.

That’s exactly what clouds do. So WASP-127b, this giant puffy planet orbiting way too close to its parent star, has clouds. The astronomers weren’t able to tell what the clouds are made of, how much they cover the planet, or what the weekend weather outlook is, which just adds to the mystery.

Oh, you want some more? Sure. The astronomers found that WASP-127b orbits its parent star the wrong way – its star spins one way while the planet orbits the other. Also, it has a really janky orbit, tilted far away from the plane of the rest of the planetary system. The astronomers suspect that there might be another, undiscovered planet in the system, and its gravitational influence is to blame for the weird orbital dynamics.

In short, WASP-127b is a hot mess of a planet, but at least it’s an interesting hot mess.

Dive Deeper into the Cosmos

Paul M. Sutter is an astrophysicist at Stony Brook University and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of How to Die in Space.

Next Up

Quiz: Test Your Space Exploration Knowledge

Ahead of the historic May 27th NASA and SpaceX crewed space launch, test your space exploration knowledge!

NFL SUPER STADIUMS Follows the Epic Journey of Building SoFi Stadium

In partnership with the NFL, Discovery and Science Channel go behind the scenes and follow the remarkable journey of constructing SoFi Stadium in an all-new, two-hour special, NFL SUPER STADIUMS premiering Wednesday, September 9 at 8P on Science Channel and Saturday, September 12 at 11A on Discovery.

The Best Planets are Rogue Planets

We can debate the status of objects in the solar system all day long, arguing if little Pluto is a planet or not. But to tell you the truth, any planet in any solar system got the short end of the stick. The real winners of the galactic game are the travelers, the roamers, the rogue planets.

Why Charting the Most Extreme Objects in the Solar System Matters

So the astronomers called it “FarFarOut”, which is mostly a joke because the last time they found such a distant object it they nicknamed it “FarOut”, and this new world is much, much, farther out.

Jupiter Makes Its Closest Approach to Earth in Nearly 60 Years

The last time Jupiter appeared this large and bright in the sky was in October 1963.

The First Exoplanet Found…Outside the Galaxy!

This new planet has had a pretty rough life.

Why Mercury Matters

At first, the planet Mercury isn't much to look at. It has a surface only a mother could love, as desolate and empty as the Moon and pock-marked with crater after crater. But this planet has a secret, which has folks wanting to know more.

Yet Another Exoplanet That You’ll Never Want to Visit

Ready for an exotic vacation? How about…really exotic? Tired of tropical beaches or snow-covered mountains? Let’s go…out of this world.

How Exoplanets Became the Next Big Thing in Astronomy

To date, we know of over 5,000 planets outside the solar system. And astronomers suspect that there may be *checks notes* around a trillion more in our galaxy alone. The search for exoplanets is one of the hottest topics in astronomy, with expensive telescopes and giant collaborations all searching for the holy grail of the 21st century: an Earth 2.0, a habitable world like our own.

Why Astronomers Care About Super-Old Galaxies?

A long time ago, our universe was dark.It was just 380,000 years after the big bang. Up until that age, our entire observable cosmos was less than a millionth of its present size. All the material in the universe was compressed into that tiny volume, forcing it to heat up and become a plasma. But as the universe expanded and cooled, eventually the plasma changed into a neutral gas as the first atoms formed.

Related To: