寻找适合居住地星球

It’s been nearly 20 years since astronomers first identified a planet outside our solar system. More than 500 exoplanets have been discovered since then, yet it’s not clear if even one of them might be habitable. Now, astronomer Eric Agol at the University of Washington says we’ve been looking in the wrong places. If we want to find planets that could support life, he says we should look at stars that are dying. He floats that suggestion in the Astrophysical Journal Letters. [Eric Agol, "Transit Surveys For Earths In The Habitable Zones Of White Dwarfs"]

White dwarves are the remnants of stars like our sun that start to cool. But they’re still warm enough to keep a planet at a nice cozy temperature…if that planet is close enough. Say, 10 to 100 times closer than Mercury gets to the sun. And that distance is what makes white dwarves so attractive. To astronomers, anyhow. Because a planet that close to its star would dim the dwarf’s light as it passes. The dimming could be detected by even a puny one-meter telescope.

Agol suggests we survey the 20,000 white dwarves closest to Earth. Finding a planet would give us a good place to look for life. Or maybe someday live.

—Karen Hopkin