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What Can We Actually Find on an Exoplanet? Part 2: A Machine to Find Another Earth

(This is Part 2 of a series on what we can actually find on an exoplanet. Read Part 1 first.)

It’s not hopeless, because the James Webb isn’t the last telescope we’ll ever build.

Next up on the docket of space launches is the Nancy Grace Roman Space Telescope, which will mostly run deep-universe cosmology surveys but will also, almost incidentally, pick out millions of exoplanets using a trick called microlensing. That only reveals that a planet exists, not whether it can support life, which is very cool but not our subject today.

Our subject today is what comes after that: the Habitable Worlds Observatory. It’ll surely be renamed after someone famous eventually, but for now it’s a little more than a sketch in a notebook. The HWO is like a super-James Webb, and the James Webb was already a super-Hubble, which makes this a super-duper Hubble. And despite a planned mirror actually a touch smaller than the James Webb’s, it carries one instrument that earns it the title of biosignature hunter: a coronagraph.

A coronagraph is a very simple device that has to be built almost impossibly well. It’s basically a bit of metal shaped to blot out the light of the parent star while you look at the system around it. You know how you cover the Sun with your thumb to see something near it in the sky? It’s like that, except that to reach the precision it needs, it actually uses a series of exquisitely shaped masks that exploit the wave nature of light. The starlight is made to destructively interfere with itself and cancel out at exactly the spot where the planet’s light is slipping through untouched.

The whole point is to stop relying on filtered starlight to do our dirty work and instead get a picture of the planet itself, in all its reflected-light glory. And this is an undertaking, to put it mildly. To directly image an Earth-like planet around a Sun-like star, you have to pick out something roughly ten billion times fainter than the star sitting right next to it. Picture standing on a beach in California and trying to spot a single match being struck next to a lighthouse in Japan. The star is firing ten billion times more photons at you, at every wavelength you care about, than the planet is, and essentially all of the HWO’s design effort goes into building a coronagraph that can pull the planet out of that glare.

The HWO is not a survey telescope. It’s not a scanner. It’s a hunter. Its stated goal is to find and directly image at least 25 potentially habitable worlds and take their pictures. Hubble was a general-purpose observatory. The James Webb was built for early galaxies first and exoplanets second. Every choice about the HWO, the mirror size, the coronagraph, the wavelength range, the stability requirements, was made with “find life on another world” sitting at the top of the list.

But to reach that kind of precision, to hit the contrast level where we can actually pick out the fine details of a planet’s light, the mirror has to hold its shape to within picometers. That means the whole telescope, floating in space, buffeted by temperature swings and the vibrations of its own machinery, has to stay stiller than the jiggling of individual atoms. If you blew the HWO mirror up to the size of the continental United States, keeping it stable to picometers would be like holding that entire surface flat to within the width of a human hair.

I’ll be honest with you: we don’t currently know how to do this. That’s why, even though it’s about the same size as the James Webb, the HWO is a generation-scale engineering problem, and why it won’t launch until the 2040s at the earliest.

Which is fine, because hunting biosignatures isn’t only a technology problem. It’s also a theory problem. Even with perfect data, we’d hit a wall, because to turn a spectrum into “here’s how much of each gas is in this atmosphere,” we need reference tables built from laboratory measurements and theoretical calculations: how much light does methane absorb at 3.3 microns, at what temperature, at what pressure, mixed with what other gases. These are called opacity models, because of course they are.

Imagine you’re a bartender trying to identify a mystery cocktail by taste alone, except your recipe book was written by someone who tasted each ingredient one at a time, at room temperature, and never actually mixed anything. Now you’re handed a drink that’s been chilled, shaken, and blended with five other flavors. Your recipe book is technically correct, the best kind of correct, but the actual taste in your mouth is doing things the book never anticipated. Sometimes you can’t even tell if that’s gin or vodka.

That’s roughly where we are with exoplanet atmospheres. We know how methane absorbs light at room temperature in a lab. We know how water does. We don’t really know what happens when both sit at 700 Kelvin and ten atmospheres of pressure, mixed with hydrogen and traces of a dozen other gases, billions of molecules deep. There’s so much uncertainty in these models that ten astronomers could look at the exact same spectrum and walk away with eleven different interpretations, some of them thrilling hints of life and some of them nothing at all. This is why we keep getting headlines about big biosignature discoveries, only for those studies to be quietly walked back a few months later when nobody’s watching. The devil is in the details, and with biosignatures it is all details.

But we’ve got time, a couple of decades, to sort it out before the HWO starts pointing at planets and telling us what they’re made of. And yes, you heard me right: about two dozen candidate planets, total. We’re putting a lot of eggs in one basket, because honestly it’s the only basket current technology gives us, and even that is stretching the meaning of “current technology.”

And all of that, for our first pictures of potentially habitable worlds to amount to a single pixel of light.

Is that enough?

In Part 3, it turns out one pixel is enough for a shocking amount, as we learn to read oceans, continents, and even forests off a single point of light.

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Erosion reveals decades-old infrastructure ‘relics’ in Newport Beach

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A series of powerful hurricane-driven swells have surfaced forgotten remnants of Newport Beach’s infrastructure that lay buried beneath sand and water for many decades.

Videos and photos circulating on social media show piles of rocks, chunks of concrete and rusted metal rods after waves removed layers of sand along the shoreline.

Much of the erosion has occurred near the west jetty where the popular surfing spot the Wedge is located.

“We’re aware of the sand erosion and the different relics getting exposed down there,” said Newport Beach Lifeguard Battalion Chief Adam Yacenda.

Decades ago, he said, the U.S. Army Corps of Engineers built a pair of jetties to stop beach erosion and protect oceanfront homes near the entrance of Newport Harbor.

“A lot of sand has been carved away, uncovering things that haven’t seen the light of day in decades,” Yacenda said. “There are PVC pipes, wires and a railway tie underneath the water and occasionally some metal.”

The storm swells come amid a growing El Niño, a climate pattern characterized by warming ocean waters in the central and eastern tropical Pacific, as well as increased rainfall. The 2015-16 El Niño pattern was blamed for record beach erosion along California’s coast.

At least three hurricanes have developed in the central and eastern Pacific since July, including Hurricanes Fausto and Genevieve, which generated life-threatening waves, strong rip currents and high surf warnings for Southern California.

A youngster on the beach at the Wedge in Newport Beach is sprayed by ocean water.

Earlier this month, Los Angeles County’s Department of Beaches and Harbors announced the closure of Point Dume State Beach after high tides and surf caused extreme erosion, leaving the bluff edge unstable, with drop-offs of up to 8 feet in some areas.

In Carlsbad, strong surf and high tides stripped away much of the sand and damaged a parking lot at Tamarack State Beach, which had received about 400,000 cubic yards of sand dredged from a nearby lagoon in early 2025, according to SFGate, which was first to report the issues in Newport Beach.

State park officials did not immediately respond to a request for comment.

The erosion in Newport Beach comes after a busy summer for lifeguards, who in June had to take roughly 12,000 preventive actions, including moving people out of hazardous situations and carrying out more than 500 rescues.

The erosion of the beach now has sparked curiosity about what may be buried under the sand and safety concerns for local surfers at the Wedge.

Some residents believe the exposed material is part of an old groin that was built long before it expanded into a jetty.

Jetties are long barriers often constructed of boulders or concrete at inlets or harbors to keep navigation channels open, while groins are shorter and often are built on open beaches to stop erosion and widen the sand area.

A spokesperson for the city of Newport Beach did not immediately respond to questions about the material exposed on the beach.

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What Can We Actually Find on an Exoplanet? Part 1: The Atmospheric Fingerprint

In 1990, the Voyager 1 spacecraft, then six billion kilometers from Earth and destined to become humanity’s most far-flung emissary, turned around and took a picture of home. The resulting image is now legendary: a haunting portrait of our tiny, fragile world, a single pale blue dot suspended in a sunbeam.

Now imagine you’re an alien species hunting for life on other worlds. You’ve found a promising candidate, a rocky planet orbiting a medium-sized star in its habitable zone. And let’s say that even with the most advanced technology at your disposal, all you have is that pale blue dot. Or worse: a single pixel, an image not even big enough to make out a sphere.

Everything you will ever know about us has to come out of that one pixel. Oceans, continents, weather, whatever life crawls or breathes or builds down here, all of it collapsed into one tiny smudge of light.

What could you figure out? It turns out an absurd amount, but only if you’re clever, patient, and willing to build the most ridiculous telescopes imaginable.

Let’s start with what we can do today, with the machines already at our fingertips. Well, they’re sitting a million or more kilometers from Earth, but they have dedicated channels for beaming data home, so that’s sort of like fingertips.

The main trick we use to figure out what’s on another planet, and especially to hunt for life there, is called transit spectroscopy. When a planet crosses in front of the face of its parent star, an event we call a transit, a sliver of starlight passes through the planet’s atmosphere on its way to us. And that atmosphere is full of stuff, mostly molecules, and different molecules absorb different wavelengths of light. Water absorbs certain wavelengths, methane others, bits of cheese still others. Every molecule has a unique fingerprint of colors it likes to swallow.

So all you have to do (and I’m airily waving away a mountain of technical difficulty here) is compare the star’s light with the planet in front of it to the star’s light without the planet in front of it. Whatever wavelengths went missing got absorbed by the atmosphere, and there is your fingerprint, written right into the light.

The reason there’s a mountain of technical difficulty, of course, is that the signal is fantastically tiny. For an Earth-sized planet around a Sun-like star, the atmosphere modifies the starlight by about one part in ten thousand. And that’s on a good day, with ideal conditions and a strong signal.

Which is exactly why we build monster telescopes like the James Webb. Launched in 2021, it carries a 6.5-meter mirror, big enough to tease out these kinds of minuscule differences. It’s an incredible machine, with one important caveat: it wasn’t built specifically to find life. It was built to do a hundred other jobs well too, from early galaxies to star formation to black holes to planetary atmospheres. Biosignatures, the signs of life, are just one item on a very long menu.

And that means it’s not going to hit a home run here. We’re hunting for four molecules in particular: oxygen, ozone, methane, and water, which together make up the classic biosignature cocktail. Why these four and not, say, literally anything else? Because on Earth, they are the atmospheric evidence for biology. Photosynthetic life exhales oxygen. Sunlight in the upper atmosphere converts some of that oxygen into ozone, which then blocks ultraviolet light, one of the reasons Earth is habitable in the first place. Microbial life, especially the anaerobic kind that hates oxygen, exhales methane: cow guts, swamps, termites, deep-ocean vents. And water isn’t a biosignature by itself, but it’s the solvent that every kind of life we know of requires.

These four are what life on our planet lives and breathes, and since Earth is the only example of life we have anywhere, it’s as good a starting point as we’re going to get.

Crucially, they need to show up as a package. A lot of oxygen on its own isn’t enough, because there are dull, purely chemical reactions, like sunlight breaking apart water vapor, that can produce it in abundance. Same with methane: belching volcanoes can make plenty. So what we’re really after is these gases in disequilibrium, an abundance of them coexisting when they have no business coexisting, unless something keeps topping them off. Oxygen and methane in the same atmosphere at the same time would normally react and cancel each other out within a few thousand years. See them together, and something is replenishing the supply.

On Earth, that something is life. One of the defining features of living systems is that they shove a planet out of chemical equilibrium and hold it there. So that’s the signature we go looking for elsewhere.

And the James Webb? It’s got a chance, I’ll give it that. But not a good one. The trouble is that the smallest signal it can reliably detect for anything is around 10 parts per million, meaning it simply can’t confidently measure an atmospheric signal fainter than that. For an Earth-like planet around a Sun-like star, the biosignature cocktail is much fainter than that. The James Webb could be staring straight at a living world and it would just look like noise.

Its one real shot is a rocky planet around a small red dwarf star. Because those stars are so dim, the planet’s atmosphere blocks a bigger fraction of the total light, boosting the signal. But that’s a genuine stroke of luck: you need such a system, and you need it close enough for the trick to work. Best case, we’re talking maybe two or three planets over the entire lifetime of the James Webb, and that’s just to have the chance to even glimpse biosignatures. Those two or three worlds could easily be dead, and statistically they probably are, because most worlds are dead.

So is it hopeless?

In Part 2, we meet the machine being designed for one job and one job only: to find another living Earth.