Super-Earths are what scientists call extrasolar planets that exceed Earth’s overall mass but fall behind our solar system’s gas giants such as Uranus and Neptune. Regardless of the name however, they are not necessarily similar in composition or habitability to our planet, just simply defined by a mass higher than Earth’s but smaller than approximately 15 Earth masses.
The first super-earths ever discovered by mankind, around the PSR B1257+12 pulsar, were detected by observing changes and effect of potential planets over the system’s star through gravity. In the following years, research was facilitated by space telescopes, such as the Microvariability and Oscillation of Stars (MOST) Space Telescope.
Recently however, one of the super-earths known – more specifically– was observed using ground telescopes at the international observatory on La Palma in Canary Islands, as the planet temporarily passed by in front of its solar system’s sun nearly 41 light years away. Scientists from Queen’s University, Belfast were able to detect it during the exoplanet’s 2-hour long trip in between Earth and 55 Cancri e’s star, when the light coming from it was reduced by 0.5% in intensity. Such a small difference is difficult to observe and requires the light from the star to pass through the very edge of the atmosphere where vapor absorbs some of the light making the difference noticeable at certain wavelengths.
There are a few things known about this super-earth: its mass is about 7.8 Earth masses but only measures twice more in diameter. Recent studies confirmed the fact that it takes nearly 18 hours for it to orbit around the system’s star, and it is the innermost planet from was so far discovered to be a 5-planet system. In spite of showing presence of vapors in its atmosphere, it is most likely uninhabitable, given its proximity to the star and inherent temperatures which scientists have calculated reach 1,700 degrees Celsius. But the approach used behind the 55 Cancri e observation could pave a solid path to future discoveries.
Astronomers are enthusiastic about the idea; with two missions to discover other habitable planets – TESS (Transiting Exoplanet Survey Sattelite) and CHEOPS (Characterising Exoplanet Satellite) – scheduled for 2017, being able to follow up on space telescope discovering from Earth’s surface will lower costs and speed up the process considerably. And with larger scale telescopes to be designed in the future, this method could be applied to detect even Earth-sized planets dozens of light years away.