Mapping the skies for Earth-like exoplanets

January 16, 2017, CORDIS

EU scientists have helped to confirm the existence of Earth-like exoplanets and issued weather reports from planets 1 000 light years away.

It is worth remembering every now and again just how special our home planet truly is. Thanks to its solid outer crust and its propitious position at a distance from the sun where liquid water can exist, it is uniquely capable of supporting life.

Very few other have ever been discovered which satisfy these 'habitability' criteria. Nonetheless scientists, such as those involved in the EU-funded ETAEARTH project, are beginning to find potential candidates. For example Kepler-78b, an Earth-sized planet with a composition remarkably similar to our planet, was recently found some 400 away. This search could ultimately hold the answer as to whether or not we are alone in the universe.

The four-year ETAEARTH project, due for completion at the end of 2017, aims to provide for the first time an accurate picture of just how common earth-like planets are in our galaxy. This is being achieved by combining data from NASA's Kepler space observatory with readings from a new ESA spectrograph called HARPS-N, which can detect tiny velocity signals from planets as small as Earth. The results are being analysed by a team of experts from Italy, the UK, Switzerland and the US.

This combination of Kepler and HARPS-N data has enabled scientists to learn much more about such planets. We know for example that Kepler-78b orbits a bright star approximately 400 light years away, after it was first spotted by the Kepler Space Telescope in 2013. But what is remarkable is that ETAEARTH scientists have since been able to determine the radius of this so-called exoplanet by the amount of starlight blocked as it passes in front of its host star. They have also been able to work out the planet's mass by calculating how much gravitational pull makes Kepler-78 wobble.

From this, scientists were then able to calculate Kepler-78b's density and determine what it is made of. They concluded that the exoplanet is 1.2 times the size of Earth and 1.7 times more massive, suggesting that it is primarily made of rock and iron. This makes Kepler-78b the most Earth-like exoplanet to have ever been discovered.

Of course, Kepler-78b is just one of a large number of exoplanets to have been found. The ETAEARTH project hopes to obtain statistical information that will help astronomers understand the broad trends of exoplanet distribution in the habitable zone of their stars. In addition, the project hopes to provide with a clearer understanding of what conditions on these planets are actually like.

For example, the project has been able – for the very first time – to observe weather on an exoplanet. The cloudy atmosphere of HAT-P-7b, a gas giant about 16 times larger than Earth and more than 1 000 light-years away, reflects light as it orbits around its star. By observing how this light changes, a complex picture of the planet's cloud patterns has been built up over the past four years, giving the most detailed determination yet of weather on an exoplanet.

With another 12 months to go the ETAEARTH is sure to bring up more intergalactic surprises, and edge us closer to knowing whether we are in fact alone.

Explore further: Measuring the mass of a Mars-size exoplanet

More information: Project website:

Related Stories

Measuring the mass of a Mars-size exoplanet

June 18, 2015

Determining the size of an Earth-size exoplanet by the amount of starlight it blocks hundreds of light-years away once was the realm of science fiction. Measuring the mass of such a small planet based on its gravity was ...

Kepler's six years in science (and counting)

May 13, 2015

NASA's Kepler spacecraft began hunting for planets outside our solar system on May 12, 2009. From the trove of data collected, we have learned that planets are common, that most sun-like stars have at least one planet and ...

Recommended for you

Observatories team up to reveal rare double asteroid

July 13, 2018

New observations by three of the world's largest radio telescopes have revealed that an asteroid discovered last year is actually two objects, each about 3,000 feet (900 meters) in size, orbiting each other.

'X'-ploring the Eagle Nebula and 'Pillars of Creation'

July 13, 2018

The Eagle Nebula, also known as Messier 16, contains the young star cluster NGC 6611. It also the site of the spectacular star-forming region known as the Pillars of Creation, which is located in the southern portion of the ...

First space tourist flights could come in 2019

July 13, 2018

The two companies leading the pack in the pursuit of space tourism say they are just months away from their first out-of-this-world passenger flights—though neither has set a firm date.

South Africa unveils super radio telescope

July 13, 2018

South Africa on Friday unveiled a super radio telescope, a first phase of what will be the world's largest telescope in a project to try to unravel the secrets of the universe.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jan 16, 2017
"This makes Kepler-78b the most
Earth-like exoplanet to have ever been discovered.":

I'm sorry but this simply is not true. Kepler 78b temperature is estimated to be about 2000 Celsius.
In terms of radius, it is similar to Earth, but emphatically not similar overall.

Considering both radius and temperature, there are many other exoplanets that are more similar to Earth.

Pls consider double checking with Wikipedia .

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.