Telescope searching for exoplanets finds 8 Super-Earths and one may have a biosignature

Super-Earths are exoplanets that are more massive and larger than our planet but are smaller than giant planets like Jupiter and Saturn. The question that remains is: could a Super-Earth be the long-awaited Earth 2.0?

TESS found 8 exoplanets that are considered Super-Earths. Credit: Bing/DALL-E
TESS found 8 exoplanets that are considered Super-Earths. Credit: Bing/DALL-E

One of the biggest searches in astronomy is for Earth 2.0. Earth 2.0 would be an exoplanet with characteristics very similar to ours, from composition, atmosphere and even size. However, smaller planets are more complicated to find than larger ones.

This is one of the reasons that the exoplanets found are usually gas giants like Jupiter and Saturn. Exoplanets the size of Earth, or even smaller ones like Mars, are found at a lower frequency precisely because techniques are better for larger objects.

The space telescope used to search for exoplanets, called TESS, has found 8 Super-Earths. Interestingly, six are “key planets” which could explain the lack of planets the size between Earth and Neptune.


Planets that are not in the Solar System are considered exoplanets. They can be found around stars or even alone. Recently, a study even suggested the term blanet of exoplanets around black holes.

The great interest of scientists is the possibility of finding an exoplanet that is similar to Earth. This could indicate an environment that would be conducive to life. Therefore, seeking what is called Earth 2.0 is currently astronomy's biggest objective.

The big question in astronomy

At the end of each decade, astronomers from around the world come together to decide the big question for the next decade. Between 2019 and 2021, several articles were published with this intention, known as Astro2020.

The consensus among astronomers was that the focus of this decade would be on exoplanets and the search for Earth 2.0. The James Webb Space Telescope itself was launched with this objective, in addition to studying the young Universe. In 2019, the Nobel Prize in physics went to scientists who found an exoplanet for the first time.

How to find exoplanets?

Planets do not emit their own light the way stars do. Finding them is a complicated mission. The most common way is through transient events of exoplanets.

A transient event happens when an exoplanet passes in front of the star it orbits, causing the star's luminosity to drop slightly for a short period.

By calculating the time that the star's luminosity decreases and the period over which this happens, it is possible to find exoplanets. The disadvantage is that other bodies can cause the same effect as other stars or even the star itself varies its brightness.


TESS is a space telescope that was launched as a successor to Kepler. The idea of TESS is to study these transient events and be able to identify exoplanets in stars neighboring the Sun, that is, stars that are in a nearby region.

TESS is a space telescope with the aim of searching for exoplanets through transient analysis. Credit: NASA
TESS is a space telescope with the aim of searching for exoplanets through transient analysis. Credit: NASA.

TESS has already found 400 exoplanets that have been confirmed and more than 6,000 await confirmation. Confirmation comes through further observations or statistical methods that may even include the use of machine learning.

Why don’t we find 'average' planets?

In the study of exoplanets, there is a problem related to their population. Because it is done through transients, larger planets like Jupiter and Saturn are found more easily. Despite this, planets like Earth and even smaller ones have also been found.

But there is a range of masses in which planets of this type are difficult to find: between 1.5 times the mass of Earth to twice the mass of Earth.

The question remains: why are these planets not found? And if they are not formed with the same frequency, why? That's why exoplanets between these masses are called “key planets”.

Six key planets

TESS has identified eight Super-Earths that are exoplanets that are more than the mass of Earth to the mass of Neptune. Six of these objects fall into the range considered key planets and may help us explain their lack in observations.

One explanation is that key planets can lose their atmosphere through some process and the six key planets found by TESS can help us answer this. Simulations of the planets were carried out and one of them showed something unprecedented.

The planet with methane

To understand the atmosphere of these planets and their composition, the researchers who led the work carried out simulations. One of these simulations showed that one of them may present an amount of methane gas that represents a biosignature.

It is still too early to confirm whether there is indeed the presence of methane in one of them. The group argues that the James Webb telescope is essential to confirm the presence of this gas in the exoplanet's atmosphere.

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