A global team of professional and amateur astronomers has found a solar system thousands of light years away that looks like a scaled-down version of our own.
Two planets proportionally similar to Jupiter and Saturn are orbiting a star in a constellation called Scorpius, which is 5,000 light years, or 30 quadrillion miles, away.
The finding suggests that solar systems patterned like ours may be common, something astronomers have long believed to be true, said Scott Gaudi, assistant professor of astronomy at Ohio State University and lead author of the study. The study was published in the Feb. 15 issue of the journal Science.
"I think this is very encouraging in terms of the hope that there are other solar systems like our own out there," Gaudi said. "This is a good step in the direction of trying to answer these questions."
Scientists detected the planets using a technique called "gravitational microlensing," which required constant nighttime monitoring of the faraway constellation over a 10-day span. To do so, researchers relied on amateur astronomers Jennie McCormick and Grant Christie, both based in Auckland, New Zealand, to collect data during the American daylight hours.
Microlensing, long considered the "poor cousin" of planet-finding techniques, uses Einstein's theory of relativity to find massive objects in outer space. When a close and a distant star align, the foreground star acts as a lens, magnifying the background star. Gravity of the planets near the background star further distorts the image. Scientists calculate the mass of the planets by measuring the extra distortions in that background star.
"In general, the bigger the planet, the larger the area is that it distorts," said Andrew Gould, professor of astronomy at Ohio State, and one of the study's co-authors. "If the planet is bigger, it will have fluctuations that last longer."
This discovery marks the first time microlensing has been used to find more than one planet. Only four other planets have been detected by this method, which is a tricky and time-consuming process, also requiring tens of thousands of hours of mathematical modeling.
"There's a lot of triage involved," Gould said. "It's really the result of an incredibly chaotic process." Gould also heads the MicroLensing Follow-Up Network, a collaboration of professional and amateur astronomers who assist in collecting data for microlensing events.
There is much that is still unknown about the planets. Astronomers don't know how big they are, what they are made of, or whether other smaller planets orbit the same host star. Any planet the size of earth would have escaped detection by the team because it would be too small to be seen with current technology at that distance.
"To see an earth directly would be like trying to find a firefly within one inch of a search light," said Sara Seager, professor of planetary science at the Massachusetts Institute of Technology.
But astronomers do know the mass of both planets and the mass of the star that they orbit. They know that these planets - believed to be gas giants - are the same distance from their sun as Jupiter and Saturn are to ours. And like Jupiter compares to Saturn, the larger planet is triple the size of the other.
"The star itself is smaller and dimmer than the sun," Gaudi said. "The planets are also smaller. But the amount of sunlight is not that different than ours, because the planets are closer."
Microlensing is particularly useful when objects are too far away to be located by more traditional methods, such as radial velocity, or the "wobble" method.
So far, Scientists have found about 270 planets and about 25 multiple-planet systems, mostly using the wobble method. Seager said most of these planets "are just crazy" -- giants compared to earth and clustered closer to their sun than those in our solar system.
Scientists believe this is because, the wobble method, by its very nature, is more sensitive to finding planets that sit closer to their parent star.
"[Microlensing] is the only technique that can find Saturn-like planets at Saturn-like distances from the star," Seager said. "We're seeing a triumph of a new technique and a vindication for people working so hard to find planets that no other technique can find."
Note the caveat in the article title, "might mimic." This is good science because it is a recognition of sciences' limits.
Also note the use of amateur astronomers which is recognition of these "amateurs" do good science. This is especially true of Astronomy.
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