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Life On Other Worlds

Scientists believe there might be life on planets that don’t rotate, or spin.

A planet with a dark side, a light side, and a belt in the middle.

Ana H Lobo

This artistic rendition shows what a planet’s terminator zone might look like.

Scientists are searching for Earth-like planets that could sustain life. But what if life could exist on planets that have little in common with Earth? Astronomers from the University of California, Irvine, are studying the possibility of life in areas called terminator zones.

Terminator zones exist on planets that don’t rotate, or spin. Earth’s rotation ensures that no one side of the planet is always facing the Sun. It’s the reason why we have days and nights. But on planets that are tidally locked, meaning they don’t rotate, one side is always facing the planet’s star while the other side is always dark. A thin strip, or belt, around the planet sits between the light and dark sides. It’s in this belt, the terminator zone, that conditions could be just right for liquid water—and life.

“You want a planet that’s in the sweet spot of just the right temperature for having liquid water,” said astronomer Ana Lobo, who led a recent study of such planets. “This [would be] a planet where the dayside can be scorching hot, well beyond [livability], and the night side is going to be freezing, potentially covered in ice. You could have large glaciers on the night side.”

How common are tidally locked planets? Pretty common, scientists say. These planets orbit M-dwarf, or red dwarf, stars, which scientists believe make up about 70 percent of stars in the known universe. That doesn’t mean all tidally locked planets have livable zones. But it does raise some interesting possibilities about what else is out there.


Headed To the Moon

Four people pose in orange and blue spacesuits.


The Artemis II crew includes (clockwise from left) Christina Koch, Victor Glover, Jeremy Hansen, and Reid Wiseman.

NASA has named the four astronauts who will take part in Artemis II, the first crewed mission to the Moon since 1972. In a mission scheduled for late 2024, the astronauts will orbit the Moon 10 times and then return to Earth. Meanwhile, they will perform tests in preparation for a 2026 mission in which astronauts will land on the Moon. 

Reid Wiseman, Commander

Born in Baltimore, Maryland, Reid Wiseman lived and worked on the International Space Station for 165 days in 2014. While on the space station, he helped conduct scientific experiments and led 13 hours of space walks outside the station. Wiseman also commanded the NEEMO 21 Mission, in which astronauts conduct a simulated space mission underwater.

Victor Glover, Pilot

Born in Pomona, California, Victor Glover piloted a SpaceX spacecraft to the International Space Station in 2020 and then served as Flight Engineer aboard the station during a long-term mission. While living on the station, Glover helped conduct scientific experiments and participated in four spacewalks. With Artemis II, Glover will become the first Black American ever to go to the Moon.

Christina Koch, Mission Specialist

Born in Grand Rapids, Michigan, Christina Koch set a record for the longest single spaceflight by a woman, with a total of 328 days in space while living and working on the International Space Station in 2019 and 2020. During this time, she helped conduct scientific experiments. She also participated in six spacewalks, including three all-women spacewalks. With Artemis II, Koch will become the first woman ever to go to the Moon. 

Jeremy Hansen, Mission Specialist 

Born in London, Ontario (in Canada), Jeremy Hansen will become the first non-American to fly to the Moon. Hansen trained as a military pilot and has explored the deep ocean as part of a project to simulate deep-space exploration. Artemis II will be his first trip to space. 

Artemis II is part of the larger Artemis program, which aims to someday land astronauts on Mars. 

“Am I excited?” Koch said when the announcement was made. “Absolutely!”

Did You Know?

NASA/JPL-Caltech/M. Russo, A. Santaguida (SYSTEM Sounds)

Each musical note in this video represents the discovery of an exoplanet. What happens as time passes?

An exoplanet is a planet that exists outside our solar system. As of March 2023, more than 5,300 exoplanets had been discovered!

Spot the Planet

NASA/JPL-Caltech/R. Hurt (IPAC)

This illustration gives an idea of what a telescope might show as two planets pass in front of their star.

It’s fairly easy for telescopes to detect potentially habitable (livable) planets orbiting M-dwarf stars. Here’s why.

An M-dwarf star is fairly cool, as stars go. So, for a planet in its solar system to be warm enough for liquid water, it needs to orbit close to the star. A planet in that habitable region would complete a full orbit about every few weeks. 

Okay, so what does that have to do with our telescopes detecting planets? A telescope can detect a far-off planet when the planet passes in front of its star, changing the star’s brightness. If a planet does this every few weeks, we have a better chance of finding it.

Hello Out There

NASA, ESA, and F. Summers, G. Bacon, Z. Levay, J. DePasquale, L. Hustak, L. Frattare, M. Robberto, M. Gennaro (STScI), R. Hurt (Caltech/IPAC), M. Kornmesser (ESA)

Until very recently, humans knew only about the planets in our own solar system. No one could confirm that any other planets existed until the first exoplanets were discovered in 1992. Since then, more than 5,300 exoplanets have been discovered. That makes our eight-planet neighborhood look pretty tiny!

It also raises a question… What else is out there?

You can read about how astronomers study exoplanets, and much more, at Britannica School.






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