For the first time ever astronomers have detected visible light spectrum reflected off an exoplanet.

Astronomers used HARPS machine at the European Southern Observatory’s (ESO) La Silla Observatory in Chile.

The discovery is led by Jorge Martins from the Instituto de Astrofísica e Ciências do Espaço (IA) and the Universidade do Porto, in Portugal, who is currently a PhD student in ESO in Chile.

Astronomers have detected the first exoplanet 51 Pegasi b around a normal star.

The exoplanet lies 50 light years from Earth in the constellation of Pegasus. It was discovered in 1995 and the first confirmed exoplanet orbiting a normal star like sun.

It is also regarded as archetypal hot Jupiter, a class of planets now known to be relatively commonplace, which are similar in size and mass to Jupiter, but orbit much closer to their parent stars.

More than 1900 exoplanets in 1200 planetary system has been confirmed after the first discovery.

New discoveries are promised with this technique and with the advent of next generation instruments including ESPRESSO, on the Very Large Telescope (VLT), etc.

Currently the technique known as transmission spectroscope is most widely used, the technique is to examine exoplanets atmosphere by observing the host star’s spectrum as it is filtered through the planet’s atmosphere during transit.

Alternative technique is to observe the system when the star passes in front of the planet, which provides information about the temperature of exoplanet.

The new technique does not depend on finding a planetary transit, and so can be used to study many more exoplanets. In this technique planetary spectrum is directly detected in visible light. By this different characteristics of planet that are inaccessible to other techniques can be inferred.

The host stars spectrum is used as a template to guide a search for a planet which reflects similar signature of light.

The only difficulty in this technique is that planets are dim in comparison with the star and the signal form the planet can be swamped by other tiny effects and sources of noise.

Martins said, “This type of detection technique is of great scientific importance, as it allows us to measure the planet’s real mass and orbital inclination, which is essential to more fully understand the system, it also allows us to estimate the planet’s reflectivity, or albedo, which can be used to infer the composition of both the planet’s surface and atmosphere.”

Nuno Santos, co-author of the study said, “We are now eagerly awaiting first light of the ESPRESSO spectrograph on the VLT so that we can do more detailed studies of this and other planetary systems.”