No, Earth is not the most habitable planet in the Universe

Among all known worlds, Earth is the only one we know to have life. But that doesn’t mean it’s the ‘most livable’ of them all. In fact, as explained in ‘The Astronomical Journal’ by a team of astronomers led by Pam Vervoort, from the Dutch University of Utrecht, a slight change in Jupiter’s orbit would be enough to make our world even more habitable than it is. Which implies that ‘out there’ there must be planets with habitability conditions objectively better than those of the Earth itself. When a planet has a perfectly circular orbit around its star, the distance between them never changes. But those ideal conditions do not occur most of the time. Rather, most planets have ‘eccentric’ orbits around their stars, meaning they are oval in shape, so as the planet approaches its star, it receives more heat, which affects climate. Using detailed models based on available data, Vervoort and her team created an ‘Alternate Solar System’ on their computers. And in it they found that if Jupiter’s huge orbit became just a little more eccentric, it would cause big changes in Earth’s orbital path. “If Jupiter’s position stayed the same, but the shape of its orbit changed,” says Vervoort, “the truth is that it could increase the habitability of our planet.” Related News standard No The James Webb captures its first direct image of a planet beyond the Solar System Judith de Jorge standard Yes They discover two nearby ‘super-earths’, and one of them could be habitable José Manuel Nieves Between zero and 100 degrees Celsius, the Earth’s surface is habitable for many known life forms. But if Jupiter were to ‘nudge’ Earth’s orbit to become more eccentric, parts of the planet would sometimes be closer to the Sun. So large areas of the Earth’s surface that are now below zero would warm, increasing the temperatures to the habitable range. “Many are convinced that Earth is the epitome of a habitable planet,” says Vervoort, “and that any change in Jupiter’s orbit, massive planet that it is, could only be bad for us. We show that both assumptions are wrong.” Liquid water The finding, according to the researchers, can be applied to the search for habitable planets around other stars. This is how astrophysicist Stephen Kane, co-author of the study, explains it: “The first thing people look for in an exoplanet is the habitable zone, the distance between a star and a planet that allows the existence of liquid water on the surface.” But during its orbit, as happens on Earth, different parts of the same planet receive more or less direct sunlight, which causes seasons to exist. Parts of the planet can be pleasant during one season and extremely hot or cold in another. “Having water on the surface is a very simple first metric, and it doesn’t take into account the shape of a planet’s orbit, or the seasonal variations a planet might experience,” explains Kane. Current telescopes are capable of measuring the orbits of the planets. However, there are additional factors that could affect habitability, such as the degree to which a planet is leaning toward or away from a star. The part of the planet tilted away from the star would get less energy, making it cooler. And that, according to the researchers, is exactly what would happen if Jupiter were to get any closer to the Sun, as it would push the Earth into an extreme tilt, which in turn would cause large sections of the Earth’s surface to freeze. Jupiter’s orbit Ultimately, the motion of a giant planet is important in making predictions about the habitability of planets in other systems, as well as in efforts to understand their influence on our Solar System. Many things depend on how Jupiter’s orbit evolves in the future, and among them also the habitability of our own world. “It’s important to understand the impact Jupiter has had on Earth’s climate over time, how its effect on our orbit has changed us in the past, and how it might change us once again in the future,” Kane concludes.