NASA James Webb Target Acquired: A Super-Earth Covered in Lava Oceans

Monisha Ravisetti Former Science Writer
Monisha Ravisetti was a science writer at CNET. She covered climate change, space rockets, mathematical puzzles, dinosaur bones, black holes, supernovas, and sometimes, the drama of philosophical thought experiments. Previously, she was a science reporter with a startup publication called The Academic Times, and before that, was an immunology researcher at Weill Cornell Medical Center in New York. She graduated from New York University in 2018 with a B.A. in philosophy, physics and chemistry. When she's not at her desk, she's trying (and failing) to raise her online chess rating. Her favorite movies are Dunkirk and Marcel the Shell with Shoes On.
Monisha Ravisetti
4 min read
A lava ocean-covered exoplanet close to a host star.

A depiction of Webb's rocky exoplanet muse. It might be covered in lava oceans -- and even have lava rain.


What's happening

The new James Webb Space Telescope is on the cusp of full operation, and NASA just shared some potential discovery targets for the multi-billion dollar machine.

Why it matters

This space-based telescope is going to deliver unprecedented views of distant objects, giving scientists new data and new images that will reshape our understanding of the universe.

It's getting closer to showtime for NASA's cutting-edge mission to unveil an unfiltered universe and redefine the whimsy of "looking up at the stars." After a successful journey thus far -- having breezed through steps like traveling a million miles from Earth and aligning its 18 hexagonal, gold-plated mirrors -- the James Webb Space Telescope is just "weeks away" from full operation, the agency says. 

In preparation for Webb's very first cosmic discoveries, NASA is racking up a list of exciting interstellar targets. On Thursday, it announced two that definitely do not disappoint: a pair of scorching super-Earths that pretty much sound like Star Trek worlds. 

One is covered in lava oceans, and the other exists without an atmosphere.

"They will give us fantastic new perspectives on Earth-like planets in general, helping us learn what the early Earth might have been like when it was hot like these planets are today," Laura Kreidberg of the Max Planck Institute for Astronomy said in a statement.

Exoplanet muse No. 1

First up, we have exoplanet 55 Cancri e, or as NASA puts it, a super-hot super-Earth. 

This rocky orb sits something like 40 light-years from us -- one light-year is the distance light travels in one year -- and is 8.63 times the mass of our planet. 

55 Cancri e orbits a sunlike star, akin to the unbreakable bond between the Earth and sun, but because it sits less than 1.5 million miles from that star, it's extremely hot. Extremely. Hot. For context, Earth orbits the sun from a distance close to 95 million miles. That's why scientists believe rocks on 55 Cancri e literally melt into oceans of lava. And this isn't even the weirdest part. 

This ultra-hot planet's proximity to its "sun" also leads to a major mystery, and it's one that Webb is well-equipped to solve.

Super-Earth 55 Cancri e crossing in front of its parent star.

An artist's impression of super-Earth 55 Cancri e crossing in front of its parent star. 

ESA/Hubble, M. Kornmesser

"Planets that orbit this close to their star are assumed to be tidally locked," NASA said, meaning that one side of the planet must be facing the star at all times. Intuitively, scientists think such a tidal lock would make the star-facing side of the planet a lot hotter than the other, and that this heat level shouldn't really fluctuate. But… 55 Cancri e doesn't seem to exhibit these characteristics. 

A possible explanation, however, is that "55 Cancri e could have a thick atmosphere dominated by oxygen or nitrogen," Renyu Hu of NASA's Jet Propulsion Laboratory in Southern California, said in a statement. Or, alternatively, Alexis Brandeker, a researcher from Stockholm University who leads another team studying 55 Cancri e, suggests that we could be wrong about 55 Cancri e's tidal lock in the first place.

"That could explain why the hottest part of the planet is shifted," Brandeker said. "Just like on Earth, it would take time for the surface to heat up. The hottest time of the day would be in the afternoon, not right at noon." If Brandeker is right, it's also pretty likely that 55 Cancri e isn't only home to lava oceans, but also to lava rain. 

Here's where Webb comes in. 

The James Webb Space Telescope, in an artist's rendering.

The James Webb Space Telescope, in an artist's rendering. 

NASA GSFC/CIL/Adriana Manrique Gutierrez

On one hand, Hu and fellow researchers are determined to get to the bottom of this by training Webb's groundbreaking near-infrared camera (NIRCam) and mid-infrared instrument (MIRI) on the day side of the planet. Both technologies harness the power of infrared imaging to see what the human eye can't. 

Light emanating from the infrared region of the electromagnetic spectrum is essentially invisible to us, but these instruments can pick up on those photons, even when they originate in deep space, and translate them to signals readable by us mere mortals. "If it has an atmosphere, [Webb] has the sensitivity and wavelength range to detect it and determine what it is made of," Hu said of 55 Cancri e. 

An engineer in a bunny suit standing next to the Webb telescope's near infrared camera

Lockheed Martin engineer, Alison Nordt, working on Webb's NIRCam.

Lockheed Martin

And on the other hand, Brandeker and fellow researchers also plan on using NIRCam to measure the heat emitted from the lit side of 55 Cancri e during four different orbits.

Exoplanet muse No. 2

A little farther away from us than 55 Cancri e -- 48 light-years to be exact -- lies another very hot, albeit technically cooler, extrasolar planet called LHS 3844 b. This one is something like 2.25 times the mass of Earth and orbits a red dwarf star called LHS 3844. The planet's major drawing point is that it doesn't appear to have… any air? 

Or rather, it doesn't have a "substantial atmosphere," NASA said.

A dark exoplanet amid the void of space.

An illustration of LHS 3844 b, a super hot exoplanet about 48 light-years from Earth.


Webb can decode this planet's secrets by using its powerful infrared spectroscopy mechanisms. NIRCam may not work in this case due to the lack of atmosphere, but MIRI could. MIRI can't exactly "image" LHS 3844 b, but it can detect the presence of different rock compositions, like granite or basalt, and perhaps even volcanic gas -- if the planet is volcanically active, that is.

"It turns out that different types of rock have different spectra," Kreidberg said. "You can see with your eyes that granite is lighter in color than basalt. There are similar differences in the infrared light that rocks give off."

Various images showing sharpness checks for the Webb telescope's instruments

You can see an image from all of Webb's major instruments in this collage.


And while these two exoplanets are truly awesome Webb science targets, they merely scratch the surface of what this telescope could do for astronomy in the next few years. Researchers worldwide have already informally added to Webb's arsenal, like one crew identifying extraterrestrial biosignatures and another team zeroing in on a supermassive black hole ancestor.

This high-tech, multibillion-dollar scope could solve the puzzle of why Neptune is strangely getting colder and maybe even give us a beautiful, sparkly view of Earendel, the farthest star ever seen by humans

Only time will tell. Ball's in your court, Webb.