Our planet is a true oasis of life in the Universe. And this is not only because of its distance from the Sun. A NASA-funded study has shown that the key to habitability lies in the precise choreography of a planet’s motion. After conducting 93 different simulations, scientists determined which orbital parameters are necessary for terrestrial life forms to thrive.
Previously, it was believed that the most important thing was to be in the “habitable zone,” a place that is not too hot and not too cold — the ideal conditions for keeping water in a liquid state. However, new research proves that this is not enough. The speed at which a planet rotates around its axis (the length of a day) and the angle of inclination of this axis, which determines seasonality, are equally critical factors in ensuring comfortable living conditions. The results of the study are published in The Astrophysical Journal.
Rotation speed
Modeling using the powerful ROCKE-3D climate tool revealed a clear pattern. Planets with very slow rotation, where a day lasts more than 20 Earth days, are much less likely to support life. The reason is extremely cold temperatures. Long nights lead to severe cooling of the surface, which makes conditions unfavorable for complex organisms.
Role of axis inclination
For planets that rotate faster, when a day is less than 20 Earth days, the angle of the axis comes to the fore. This parameter determines the severity of seasons and the distribution of solar energy. The study showed that an inclination similar to Earth’s, at 23.44°, is most favorable for sustaining life over large areas of land. Too little or too much slope can lead to extreme climatic contrasts with large temperature differences.
Importance of orbit
Although the shape of the orbit affects seasonality, for eccentricity values up to 0.225, it is less of a determining factor for the overall habitability of land than rotation speed and inclination. However, this does not mean that it is not important for the detailed climate.
Significance for the search for life
These results, obtained thanks to NASA’s “Habitable Worlds” grant, are of great practical significance. They will help astronomers narrow down their search for potentially habitable exoplanets.
Now, in addition to finding a planet in a habitable zone, scientists will focus on assessing its rotation period and axial tilt using the latest observation methods.
The conditions that gave rise to life on Earth turned out to be even more complex, but unraveling the mysteries of its origin brings us closer to discovering our brothers in reason in the Universe.
Earlier, we explained how to search for exoplanets in the Universe.
According to NASA
