Observations of distant worlds to better know our own


The first discovery of an exoplanet was in the late 1980s, but its detection would not be confirmed until many years later.

The news of the first extrasolar planet orbiting a solar-type star was in October 1995 by Michel Mayor and Didier Queloz, Nobel Prizes in Physics 2019, with the discovery of 51 Pegasi b.

The difficulty in observations comes from the nature of these objects: planets do not shine with their own light like stars. So, their direct detection is difficult.
Over time, researchers have developed indrect methods of observations to follow the signs of the existence of a planet.

One of the most used strategies involves the study of the light of a star: for example, if the light observed decreases, it is likely that an object is passing in front of the star, partially obscuring it to our view. This method of investigation is known as the transits method.

From the study of the light curve of the star is possible to determine the radius of the planet, once known the radius of the star.


ARIEL (Atmospheric Remote-sensing Infrared Exoplanet Large-survey), scheduled for launch in 2029, has a very specific goal: to study planetary atmospheres, observing over a thousand planets. In particular, ARIEL will focus on planets with an atmosphere, studying their temperature, pressure and chemical composition. Among these planets, the largest and brightest ones will be further examined to understand the evolution of the atmosphere and climatic phenomena, such as winds.

GAL Hassin participates in ARIEL’s international observational programme ExoClock, which involves 75 observatories around the world to learn with great accuracy the characteristics of the exoplanet’ s transits in front of their parent star.

Transiting Exoplanets Observed

Celestial bodies lying outside our planetary system —therefore called extrasolar planets—are found all over the Cosmos, orbiting far and diverse stars as our own Earth goes around our Sun.
Giuseppina Micela