(ORDO NEWS) — Scientists are discovering an increasing number of planets similar to ours in other galaxies.
But how do researchers manage to determine that these planets are similar to Earth? This question was answered by expert Jeremy Lecomte.
“There are really no uniform criteria for determining whether a planet is Earth-like or not,” says Leconte.
Some scientists believe that it is enough that the planet is just rocky. This means that it has a solid surface, unlike gas giants such as Jupiter or Saturn.
To determine this, scientists first measure the planet’s radius as it passes in front of the star. So they can estimate the size of the planet.
To determine its mass, researchers look at how much the planet’s orbit causes the star to wobble. Using these calculations, they can then determine the planet’s density.
The next step is to find out if the planet’s climate is mild enough for surface water to remain liquid. This can be seen from the amount of light the planet receives, as well as from its orbit.
Some scientists believe that in order to consider a planet similar to Earth, it is necessary to find out if it has a suitable atmosphere.
To do this, they again look at the planet passing in front of the star. The presence of an atmosphere can be determined by certain gases that block certain wavelengths of light.
The hardest part is figuring out if there really is liquid water on the surface. The density of the planet may provide a clue, but the calculations must be extremely accurate.
This is because even on planets with oceans, where water covers 71% of the surface, it only makes up a tiny fraction of the total mass.
As part of the WHIPLASH project, Leconte has developed a new set of tools and techniques for analyzing the atmospheres of distant planets.
A new framework has been created to understand the physics and composition of exo-atmospheres, based on innovative 3D modeling of the planetary atmosphere.
Thanks to the launch of the James Webb Space Telescope and the ESA Ariel mission scheduled for later this decade, scientists will be able to capture the characteristics of distant planets for research.
Researchers will also be able to learn more about the exoplanets around TRAPPIST-1, a star located just 40 light-years from Earth.
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