Astronomers who have been looking for possibly inhabited planets almost always look in the “Goldilocks” zone of a star. That is the area where the conditions are most Earthlike—temperature enough to host liquid water, which is considered essential for any type of life to grow.
However, new research published in Astrophysical Journal suggest that they ought to be looking in some unexpected places. There is a better chance that life will show up on planets that are near aging, red giant stars. These stars, which are starting to go through the ending cycles of a sun’s life, have expanded greatly and may be warming planets that had been cold for billions of years.
Astronomer usually look at middle-aged stars like our own, trying to find planets that are in just the right spot for life to develop. But there aren’t many planets that we have found that fit the specifications, so it might make more sense to also look at planets circling “senior” stars. Suns that are about twice the age of our own could be radiating heat out to once-frigid planet, defrosting oceans, and finding new life or old eco-systems that come back to life under the changing conditions.
Right now, nearly two dozen aging stars are within 100 light years of our own solar system.
“I hope that this will actually spark an effort by people who look for planets to also look at these old stars now,” Lisa Kaltnegger, astronomy professor and director of the Carl Sagan Institute, told Space.com. “Because if you could find signatures of life on such and evolved planet—a de-frozen planet—it could tell you how (life) got started on the surface, and that would be an amazing part of the story.”
After our own sun expands to become a red giant (in a few billion years, so don’t panic), it will incinerate Mercury and Venus and Earth and Mars will be fried wastelands. But Jupiter, Saturn, and Neptune may warm up enough to sustain life.
For fantasy and science fiction writers, finding new inhabited planets could spark whole new series of books: the Un-Frozen Worlds. That’s the fun of fiction, every new little quirk that scientists discover can bring all kinds of inspiration to writers.