Researchers at the Harvard-Smithsonian Center in the US have developed a new optical device that will be installed on the Italian National Telescope to identify Earth-like exoplanets orbiting distant stars.

Initially the scientists will measure Venus’s precise gravitational pull on the sun and the technology will be used to find remote Earth-like exoplanets.

Harvard-Smithsonian Center for Astrophysics staff scientist David Phillips said: "We are building a telescope that will let us see the sun the way we would see other stars."

Astronomers have to date found over 1,700 exoplanets using the traditional transit method, which measures the decrease in brightness when a planet orbiting a distant star transits that luminous body moving directly between the Earth and the star.

"We are building a telescope that will let us see the sun the way we would see other stars."

The new laser-based technology, the green astro-comb, is being developed by Li and Phillips for use with the radial velocity method, which offers information about the mass of the distant planet and is said to detect Doppler shifts as small as 10cm/sec.

Information accumulated will allow astronomers to determine the characteristics of exoplanets they discover.

Phillips said: "The astro-comb works by injecting 8,000 lines of laser light into the spectrograph.

"They hit the same pixels as starlight of the same wavelength. This creates a comb-like set of lines that lets us map the spectrograph down to 1/10,000 of a pixel.

"By calibrating the spectrograph this way, we can take into account very small changes in temperature or humidity that affect the performance of the spectrograph. This way, we can compare data we take tonight with data from the same star five years from now and find those very small Doppler shifts."

The team used small fibres that convert one colour of light to another to build green astro-comb.

Researchers intend to test the green astro-comb by pointing it at sun and analyse its spectrum to see if they can find Venus and rediscover its characteristics.

Defence Technology