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Friday 15 February 2008 (Embargo lifted at 6am AEDT)

RAPID ROUNDUP: Solar system similar to our own: Science - experts respond

Two Australians are part of a large international team that has discovered a solar system very similar to our own. In a paper published in the journal Science on 15 February 2008, the authors describe a solar system with two planets similar to Jupiter and Saturn. Using a new technique called gravitational microlensing, they were able to see planets by using the gravitation of the star which acts like a lens to magnify the planets as they pass in front. Here the Australian team members and one other expert comment on the findings. Feel free to use these quotes in your stories.

For a copy of the paper, press release and images, please contact Carol Altman at the University of Tasmania, Phone: 03 6226 2124.

For any other queries, contact us at the AusSMC on 08 8207 7415 or email us.
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Dr John Greenhill is an astrophysicist in the School of Mathematics and Physics at the University of Tasmania. He is one of the co-authors of the paper.

"The importance of this discovery is that it is the first time we have seen a solar system that looks very similar to our own. The most striking similarity is a pair of planets that are similar to Saturn and Jupiter. Most other solar systems discovered so far have planets that are very close to their star. The solar system is about two thirds the size of our solar system with a smaller and thus weaker star.

Planetary detection depends critically on the relative positions of the planets during the event. Hence we cannot exclude the possibility that the system contains cool rocky planets like Earth. They could only be discovered by microlensing but it is highly unlikely that this system will be microlensed again in our lifetime."

Dr Stefan Dieters is an astronomer in the School of Mathematics and Physics at the University of Tasmania. He is one of the co-authors of the paper.

"This study involved a tremendous collaborative effort involving around 80 experts in nearly a dozen countries. We needed to observe the solar system in continuous darkness so tracking it is a bit like passing a baton from a group of scientists in one part of the world to another group living in a neighbouring time zone. We believe there are many more systems like this one out there. Using microlensing we should, in a few years time, have a good idea just how many there are."

Dr Brian Schmidt is an astrophysicist and Federation Fellow at the Mount Stromlo Observatory at the Australian National University, Canberra.

"It is extremely exciting to find such a rich planetary system. The unique thing about this work is that it is the first time that a multiple planetary system has been found that looks so much like our own. It indicates that things that look like our solar system are not unique and by inference suggests there may well be Earth-like planets and solar systems out there. Until recently, most techniques have been unable to find similar solar systems. With the technique used by these authors, the gravity of a distant star with its planets act together like a lens to magnify the light of an even more distant background. These are rare events because the distant solar system has to drift exactly in front of the background star - a very rare occurrence! Finding planets this way is like looking for needles in a haystack.

The only note of caution is that it’s always really challenging to nail down what such planetary systems really look like from this technique, and some mistakes have been made in the past through over enthusiastic interpretation of the data. For example, it is possible for multiple star systems to mimic the signature of planets. Once we have the details of the work we will be able to assess this more accurately, but on the face of it, it looks very promising."