Scientists have discovered a distant solar system very much like our own, in which the orbits of all known planets lie in nearly the same plane and are aligned with the star's rotation.

Using data gathered by NASA's Kepler spacecraft — which is designed to monitor thousands of stars for hints of transiting planets — scientists this year discovered three planets circling a star dubbed Kepler-30, about the size and mass of our sun.

One planet, with a diameter about four times that of Earth, orbits the star every 29 days; the other two, each with a diameter at least 10 times that of Earth, orbit the star every 60 days and 143 days, respectively.

Further analysis revealed a huge, dark starspot on Kepler-30, similar to the sunspots on our sun.

By tracking the spot, researchers determined the star rotates once every 16 days or so.

That's about half the time our sun needs to rotate, which suggests Kepler-30 is a relatively young, very active star, and that, in turn, helps explain why its starspot is so large and so persistent, said team leader Roberto Sanchis-Ojeda, an astrophysicist at the Massachusetts Institute of Technology.

Detailed analyses of the variations in light reaching Kepler's sensors over 30 months revealed the three known planets pass in front of the star as seen from Earth, and repeatedly pass in front of the dark spot on Kepler-30's surface.

This reveals critical information about the distant solar system, Sanchis-Ojeda and his colleagues reported Wednesday in the journal Nature: The planets' orbits are aligned within a few degrees of one another, and the planes of those orbits are closely aligned with the rotational plane of the parent star, a remarkable parallel to our solar system.

"For the first time, we can probe a system of planets that looks like our own," Sanchis-Ojeda said.

Although the Kepler-30 system isn't the only one known to have planets orbiting in closely aligned planes, it is the first for which scientists have also determined the plane in which the parent star rotates.

"There are relatively few solar systems like ours," says Drake Deming, of the University of Maryland.