In the Search for Extraterrestrial Life, We Really Are All Star Stuff

April 18, 2012, 10:00am

In its ongoing search for life, NASA’s mantra has always been “find the water.” On Earth, where there’s water there’s life; by extension the same should hold for the rest of the solar system and others beyond it, right?

Well, maybe not. Maybe water’s not the key part to finding life, and instead it’s finding a star similar to our Sun. In fact, some astronomers are starting to think that finding a relative of our Sun might be the best shot at finding extraterrestrial life.

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Typically, the search for life focuses on finding Earth-like planets, terrestrial bodies orbiting a star in the so-called Goldilocks zone where water can exist as a liquid on its surface. But all stars aren’t all created equal. They have variable properties, brightnesses, temperatures, and can exist at different stages in their life cycle.

To find Sun-like stars that are closer to our own than not, researchers from the University of Turku in Finland, led by Mauri Valtonen, are trying to find a relative of our Sun. That’s right. A cousin or some similarly close relative of our Sun that might be out there with life-harbouring planets orbiting around it.

It’s not as far fetched as it sounds. Four and a half billion years ago when the Sun was just a baby, it was nourished in a gas-rich cloud with thousands of other fledgeling stars. Like human babies sharing a nursery, these stars could have shared germs or viruses in their developing years. These germs, the Turku team thinks, might have kickstarted life on Earth.

This theory isn’t all that different from the theory proclaiming us Martians descendants. The idea is that biological material on Mars was blasted away from the planet and carried to Earth by a meteorite. Called panspermia, this theory demands only the smallest trace of biological material travel on that meteorite.

If the germs that brought biological material to the fertile young Earth came from the Sun instead of, as the previous example suggests, Mars, then Earth’s relatives would theoretically have brought the same material to their own planets.
Unfortunately, finding the Sun’s long lost family isn’t as simple as a DNA test. We can’t compare samples of the Sun with other stars. How can we even find out where the Sun was born to determine which stars could be candidate family members?

Turns out, finding the Sun’s birthplace isn’t as hard as a DNA test. Between 1989 and 1993, the European High Precision Parallax Collecting Satellite (HIPPARCOS) catalogued 100,000 stars visible in our night sky. From that number, two are traveling at similar speeds through interstellar space as our Sun. They also have a similar metal content and composition, and are about the same age.

The Turku teams wants to hone in on these two stars, currently known as HIP 87382 and HIP 47399, and look for exoplanets. If we do find terrestrial, wet worlds orbiting these stars, the life we find could be more terrestrial than extraterrestrial. We could find our own cousins, many trillion times removed.
If we do find a sibling-star with a terrestrial planet orbiting in the goldilocks zone, we’d still a long way from communicating with our comic cousins. But the idea of our life beginning at the Sun’s birth does bring a new meaning to Carl Sagan’s famous saying that we are all star stuff.