NZ pair help find Earth's distant cousin

Husband-and-wife astronomers Dr Michael Albrow and Dr Karen Pollard. Picture / Simon Baker

A New Zealand couple have become space pioneers in a ground-breaking discovery of a new planet more like Earth than any other.

The internationally celebrated find, in which Canterbury University husband-and-wife astronomers Dr Michael Albrow and Dr Karen Pollard played key roles, marks a major step towards finding a planet capable of supporting human life.

Buoyed by this "exhilarating" discovery after 10 years' trying, the couple now hope to help uncover a planet that is a "twin Earth".

"We have just asked the question 'are there Earth-like planets out there?' The next sort of thing you could ask is 'is there life on them?' And that's really exciting," Dr Pollard said.

The new planet is about five times the size of the Earth and is likely to have a solid surface of ice or rock.

Most new planets discovered so far have been more like Jupiter, which is a hot ball of gas and liquid and has a diameter about 11 times that of Earth.

With a surface temperature of about -220C, the new planet is far from ideal for humans.

However, getting there would be a bigger problem - it is 25,000 light years away from Earth.

The new planet was discovered by a group of about 25 astronomers across the world, called the Probing Lensing Anomalies Network (PLANET), which Dr Albrow and Dr Pollard helped found. PLANET operates a network of powerful telescopes across the world.

"The reason for that is so we can monitor stars 24 hours a day," Dr Pollard said.

A complex technique called gravitational microlensing is used by PLANET to search for Earth-like planets.

"We let the gravity of a dim nearby star act as a giant natural lens for us, magnifying a distant, bright star. The extra brightening due to the presence of an orbiting planet around the lens star is the signature we are looking for," Dr Pollard said.

The Canterbury couple have not seen the new planet, ingloriously labelled OGLE-2005-BLG-390Lb, but know it is there and what it is like because of the effect of its gravity.

Dr Albrow and Dr Pollard analysed data to help prove the planet's existence, while Dr Albrow wrote computer software used in the analysis.

Mount John Observatory, in Tekapo, South Canterbury, helped confirm the discovery of the new planet.


New world

* The new planet is five times the size of the Earth and is considered a "low-mass" planet like the Earth.
* About 170 new planets have been discovered since 1995, but this is the most Earth-like.
* It orbits a red star, a fifth of the size of the sun, near the centre of the Milky Way galaxy.
* The planet's surface is believed to be rock or ice and the surface temperature is estimated to be about -220C.
* It would take a beam of light, travelling at 300,000km a second, 25,000 years to travel from Earth to the newly discovered planet.