Adam Cole | Vox

This giant laser can simulate a planet’s core

2022-08-26T11:47:55-04:00

As astronomers search for life outside our solar system, they have to try and answer one big question: What’s the recipe for a habitable planet? We tend to think about the ingredients we encounter every day: liquid water, the protective blanket of the atmosphere, a sun that is neither too warm nor too hot. But there are other factors that are probably equally important: Earth’s cooled and hardened crust, its gooey molten guts, its magnetic field, its volcanoes and deep sea vents. These are the features that fostered life as we know it, and they were shaped by unseen processes hidden deep within the globe.

In short, if we want to learn how life could arise on other planets, we need to know what’s going on under the hood.

But that’s easier said than done. As you drill down into a planet, temperatures and pressures quickly rise. Scientists and their tools wouldn’t survive a few dozen miles down, let alone a few thousand. So how can they study the insides of planets?

Enter NIF and OMEGA, by some measures the two largest lasers in the world. They inhabit large warehouse-style buildings and focus scores of intense laser beams onto the head of a pin. When facilities like these were first imagined, the goal was to create nuclear fusion, but planetary scientists quickly realized they could be used to investigate matter under core-like conditions.

The last decade has seen a flood of experiments, and the results have been bizarre. Nickel, a metal that conducts electricity, turns into an insulator. Water forms a hot, conductive ice. Hydrogen becomes a metallic fluid. Sodium, normally a shiny opaque metal, goes completely clear. These startling insights are helping scientists understand how planets form and how they might evolve to support life.

Presented by the Center for Matter at Atomic Pressures (CMAP) at the University of Rochester, a National Science Foundation (NSF) Physics Frontier Center, Award PHY-2020249.

Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the National Science Foundation.

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How to find a planet you can’t see

2022-01-27T14:25:45-05:00

Pluto was discovered in January of 1930, a tiny speck on a photographic plate. It was the most distant world humans had ever seen. Decades later, even the powerful Hubble Space Telescope struggled to get a good look at the dwarf planet — the Hubble image of Pluto is just a sickly yellow smudge.

So when astronomers set out to search for planets around other stars (a.k.a. exoplanets), they knew it wouldn’t be easy. Our closest neighbor, a little red dwarf named Proxima Centauri, is 7,000 times further away from us than Pluto. Any planets in orbit around it would likely get lost in the glare of bright starlight.

“Trying to see an earthlike planet across interstellar distances,” writes astrophysicist Adam Frank, “would be like looking from New York City to AT&T Park in San Francisco, where the Giants play, and making out a firefly next to one of the stadium spotlights.”

“To detect or study an exoplanet,” says Sara Seager, a planet-hunting astrophysicist at MIT, “we have to work with the star.”

Astronomers started monitoring stars for tiny changes that could hint at the presence of one or more planets. Early efforts focused on the search for a wobble. The pull of a planet’s gravity causes a star to circle their mutual center of gravity, and from our vantage point the star seems to swing back and forth. In 1995, a Swiss team picked up the signature of just such a wobble in the starlight from a yellow dwarf in the Pegasus constellation. They had found 51 Pegasi b: the first exoplanet around a sun-like star.

Over the next few decades, astrophysicists honed a whole range of planet-hunting tools. They learned to spot the way planets can change the shape of their stars, how a planet’s gravity can bend light, and the periodic drop in brightness when a planet passes between its star and Earth. Telescopes have become more precise and powerful, and computers have become better at sifting out signal from noise. Today, we’re closing in on 5,000 known exoplanets.

Fifty years ago, astronomers had no idea what percentage of stars had planets. A common educated guess was 20 percent, but for all we knew it could have been zero. But based on what we’ve seen since, it seems possible that every star has at least one planetary companion.

Now that we know exoplanets exist, it’s time to learn more about them. What are they made of? How did they form? And, most tantalizing, could they harbor life? We’re like sailors who have spotted a tiny rise of land on the horizon. Now we want to study this new island’s geology and biology and make contact with any inhabitants … but we have to do it all from aboard our ship, floating trillions of miles out at sea.

This video is presented by the Center for Matter at Atomic Pressures (CMAP) at the University of Rochester, a National Science Foundation (NSF) Physics Frontier Center, Award PHY-2020249.

Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the National Science Foundation.

What we found when we went looking for another Earth

2022-01-27T13:54:40-05:00

In 1584, Italian friar Giordano Bruno argued that other stars had planets of their own and that those planets had inhabitants. He had no real proof of his claims — they just felt true. But they were heretical enough to get the attention of the Roman Catholic Church. The Inquisition arrested Bruno, put his tongue in a vice, and burned him at the stake.

Four hundred years later, the idea of exoplanets (the term for planets outside our solar system) had become much more popular. Books, TV, and movies teemed with alien worlds orbiting alien suns. But one thing remained the same. We still had no proof that they existed.

Then, in 1995, astronomers discovered 51 Pegasi b — a planet orbiting a sun-like star in the Pegasus constellation. Many scientists were skeptical at first; this planet was almost too strange to be believed. Though it was about the size of Jupiter, it was closer to its star than Mercury is to our sun. Most surprisingly, it completed its orbit in just 4 days.

The years that followed brought a trickle of other discoveries, then a flood. New telescopes were sent to space and new computers crunched the data they collected. Today, we’ve confirmed the existence of nearly 5,000 exoplanets, with many more candidates waiting in the wings. Those planets paint a surprising picture of our galaxy. While astronomers once wondered if any stars have planets; now planetary systems seem the norm. 51 Pegasi b wasn’t a fluke — gas giants zipping around close to their stars (nicknamed “Hot Jupiters” or “Roasters”) are actually very common. We’ve also found lots of “super earths” — rocky worlds two to 10 times bigger than Earth.

Our solar system, on the other hand, seems less common than some had imagined. We haven’t found anything quite like it. But … it’s still early. And the data we’ve gathered so far has many scientists feeling confident that somewhere out there, just waiting for our telescopes to swing in the right direction, is a planet like Earth.

This video is presented by the Center for Matter at Atomic Pressures (CMAP) at the University of Rochester, a National Science Foundation (NSF) Physics Frontier Center, Award PHY-2020249.

Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the National Science Foundation.