Astronomers concluded that two of the four exoplanets discovered by Kepler might have the right conditions to be inhabitable.

The atmosphere of the planets could be either thin like the one on Mars, or very dense like the one on Venus, as it may as well be like the one on Earth.

The Two Earth-Size Exoplanets

The discovery was announced in May when the astronomers described three planets with the size of Earth that were orbiting TRAPPIST-1, an ultracool dwarf star. The cluster is located in the Aquarius constellation. The star is less bright than our Sun, and is also much smaller in diameter, being only one eight of its size.

This type of stars is quite common in the Milky Way, and they are relatively easy to be monitored with the current technology. The scientists believe that it may be a good idea to look for life signs on planets that resemble Earth and that they are also easy to explore.

The three Earth-size exoplanets that orbit around TRAPPIST-1 have the right temperature to foster liquid water, an essential condition for life. The scientists still have to determine if the planets have a rock composition.

A recent study shows that two of the planets may be rocky after all. The 1b and 1c planets have a similar sidereal period, which means that they pass their star almost at the same time. One of them has a period of 1.51 days and the other 2.42 days, and as they race around their star, the furthest one experiences multiple eclipses.

The Atmospheric Study

The researchers plan to study the atmosphere of the planets by using Hubble, a telescope designed in the ‘70s that may be adapted to make measurements on exoplanets.

The authors of the study used a new method in studying the atmospheric properties of the two planets. They analyzed the light spectrum for both of them at the same time, by using the double transit to study the two space objects simultaneously.

During the double transit, the star’s light showed up a limited range of wavelengths, which means that the two planets have compact atmospheres, which it commonly found on rocky planets.

The TRAPPIST-1 had been discovered by the Transiting Planets and Planetesimals Small Telescope from Chile. Because of the success met by the ground telescope, the scientists created a consortium and will try to build other four ground telescopes in Chile that would help them investigate the Southern Hemisphere sky.

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