Scientists have discovered terrestrial planets in the Milky Way
Planets outside the Solar system may be much more diverse than previously thought. In addition to worlds similar to Earth, Mars or Venus, ice giants, gas planets and even oceanides completely covered with water have already been discovered in the Milky Way. At the same time, scientists do not exclude the existence of even more unusual objects, the chemical composition of which may differ significantly from everything known in the Solar System. Vladislava Ananyeva, a researcher at the Planetary Physics Department of the Space Research Institute of the Russian Academy of Sciences (IKI RAS), told TASS about what types of planets astronomers have already found and why their composition is of particular interest.
Which planets have already been discovered in the Milky Way
The expert noted that the world of exoplanets is much more diverse than the world of stars. If most stars have a similar chemical composition, then planets can be radically different from each other.
Vladislav Ananyev
Planets can consist of iron, silicates — ironstone worlds like Earth, Venus, Mercury, Mars, that is, the planets of the terrestrial group.
However, the diversity is not limited to this. Some exoplanets consist mainly of ice and have a small atmosphere of hydrogen and helium, similar to Uranus and Neptune. Others, on the contrary, are gas giants similar to Jupiter and Saturn, which are based on hydrogen and helium.
In addition, oceanides have already been discovered in the Milky Way — planets whose surface is covered by a multi-kilometer global ocean. According to scientists, such worlds are about half composed of rocks and half of water.
Why is the chemical composition of planets so important?
When studying exoplanets, scientists estimate not only their mass, size, or temperature. Chemical composition is considered one of the key parameters, since it determines the features of the structure and evolution of the planet.
As Ananyeva explained, the chemical composition of stars is relatively uniform. Main sequence stars consist mainly of hydrogen and helium, and the proportion of heavier elements usually does not exceed 2% of their mass.
The situation is completely different for exoplanets. They can be formed from various substances, so their internal structure and properties are much more diverse. That is why studying the chemical composition allows scientists to better understand the origin and characteristics of different planetary systems.
What other worlds can exist
According to the researchers, the existence of even more unusual planets than those that have been discovered to date cannot be ruled out today.
Vladislav Ananyev
Perhaps there are more exotic worlds, carbon-rich planets. The mantle of the Earth, Mars, and the planets of the Solar system in general consists of silicates. And there may be some compounds like carbides.
According to the expert, scientists cannot yet imagine exactly what such worlds will turn out to be. However, modern astronomy does not exclude the possibility of their existence. As new exoplanets are discovered, ideas about the diversity of planetary systems continue to expand, and with them, an understanding of how unusual worlds beyond the Solar System can be.
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