Two veteran planet hunters have discovered a solar system that they say reminds them of home. The planetary system is similar in scale to our own and sparks hope of eventually finding Earth-like planets.
Are there other Earth's out there?
It took 15 years of searching, but Geoffrey Marcy and Paul Butler have found a solar system containing a Jupiter-like gas ball that is orbiting a star much like our sun.
Marcy and Butler, from the University of California at Berkeley and the Carnegie Institution of Washington respectively, announced a total of 15 new exoplanets on Thursday. Exoplanets are planets found outside our own solar system.
There have been more then 90 discoveries of exoplanets in the last decade and a half, but the previous discoveries often left astronomers wondering if our solar system is unique in the universe. The planets discovered earlier all had similar masses to Jupiter, but many had highly eccentric orbits, which could eject any Earth-like planets that might be there.
This new find holds out the intriguing possibility that other solar systems, perhaps even this latest discovery, could be home to planets similar to Earth.
A first cousin
The center of the new-found solar system, a star named 55 Cancri, is 41 light years away from the Earth, near neighbors in astronomical terms. The star is close to the sun in age, mass and brightness.
The large Jupiter-like planet there takes 13 years to orbit 55 Cancri, Jupiter takes 11.8 years to make the trip around our sun.
"We have a system that is maybe not a sibling of the solar system," Paul Butler told reporters at NASA headquarters on Thursday, "it might be more accurately classified as a first cousin."
There are two other planets in the system the astronomers also found, both very close to the star. The large gap between the two inner planets and the large outer one leaves room for a terrestrial planet in an Earth-like orbit. That gap includes the zone around 55 Cancri which is habitable.
Marcy and Butler developed their technique for detecting possible planets by investigating the wobble the planets’ gravitational pulls produce in the stars they orbit. The planets have to be large in order to produce that wobble and is why the astronomers can detect a Jupiter-sized giant, but are still not able to find Earth-sized planets that might also be present.
Such finds are probably not possible using ground-based techniques, but the next decade should bring a new generation of satellite observatories which could detect smaller planetary bodies.
"The existence of analogs to our solar system adds urgency to missions capable of detecting Earth-sized planets – first, the Space Interferometry Mission and then the Terrestrial Planet Finder," Charles Beichman, chief scientist of NASA’s Origins program told reporters.
But those days could be far off. NASA has proposed building a space-based Terrestrial Planet Finder, but no money has been put in place and the tentative launch date isn’t until 2014.