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Artist's illustration of the seven planets of TRAPPIST-1 and the Earth. Image: NASA/JPL-Caltech

The densities of seven potentially rocky planets orbiting a star 40 light-years away are surprisingly similar, according to a new study.

Why it matters: The finding is unusual because the planets in our solar system have different densities. Scientists can use the new data to home in on whether these planets, that appear similar in some ways to our own but form differently, might be suitable for life.

What they found: Seven planets orbiting the red dwarf star TRAPPIST-1 appear to all have similar densities, according to a new study in the Planetary Science Journal.

  • That measurement suggests the planets have similar ratios of iron, magnesium, oxygen, silicon and other materials.
  • These planets are about 8% less dense than they would be if they had compositions like Earth's, according to NASA.
  • "The TRAPPIST-1 system is fascinating because around this one star we can learn about the diversity of rocky planets within a single system," Caroline Dorn, an author of the paper, said in a statement. "And we can actually learn more about a planet by studying its neighbors as well, so this system is perfect for that."

Yes, but: These planets appear to be rocky instead of enveloped in a thick, gaseous atmosphere, but not much is known about their potential habitability.

  • All seven of the TRAPPIST-1 planets orbits are within what would be Mercury's orbit around our Sun.
  • While at least three of the planets orbit in an area where water could exist on their surfaces, it's not clear how conducive a red dwarf star would be to hosting life, as they are thought to be more volatile stars than our relatively mild Sun.

Go deeper

Dave Lawler, author of World
25 mins ago - World

Americans increasingly see China as an enemy

One in three Americans, and a majority of Republicans, now view China as an enemy of the United States, according to a new survey from Pew Research Center.

By the numbers: Just 9% of Americans consider China a "partner," while 55% see Beijing as a "competitor" and 34% as an "enemy."

Scoop: Leaked HHS docs spotlight Biden's child migrant dilemma

A group of undocumented immigrants walk toward a Customs and Border Patrol station after being apprehended. Photo: Sergio Flores/The Washington Post via Getty Images

Fresh internal documents from the Department of Health and Human Services show how quickly the number of child migrants crossing the border is overwhelming the administration's stretched resources.

Driving the news: In the week ending March 1, the Border Patrol referred to HHS custody an average of 321 children per day, according to documents obtained by Axios. That's up from a weekly average of 203 in late January and early February — and just 47 per day during the first week of January.

Ben Geman, author of Generate
1 hour ago - Energy & Environment

Mounting emissions data paints bleak picture on Paris climate goals

Illustration: Aïda Amer/Axios

Researchers keep finding new ways to reveal that nations are together showing very few signs of getting on track to meet the Paris Agreement's goals.

One big question: That's whether a spate of recent analyses to that effect, and scientific reports coming later this year, will move the needle on meaningful new policies (not just targets).

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