It has long been assumed that the Sun will begin to expand in about five billion years and will engulf the Earth as it transforms into a red giant. However, a new study suggests that the fate of our planet may not be so clear-cut.
Based on computer simulations, scientists conclude that the demise of the Sun could, on the other hand, push the Earth further into space, so that it would avoid imminent destruction. According to them, Mars could also escape, while Mercury and Venus are bound to be absorbed by the Sun.
“The fate of the Earth depends on a delicate balance between two forces. One is the tidal gravitational forces that would pull the Earth towards the Sun, the other is the pressure of the massive solar wind resulting from the mass loss of the expanding Sun. If tidal interactions prevail, the Earth will be engulfed by the Sun. If mass loss from the Sun prevails, the Earth will escape into an orbit larger than the radius of the Sun,” said lead author of the study, astrophysicist Mats Esseldeurs from the Catholic University of Leuven.
Scientists had previously assumed that tidal forces would overcome the pressure of the solar wind. However, the new models show that these tidal effects may be weaker than expected, according to the authors. The researchers also compared them with the observation of mass loss in the nearby star L2 Puppis, which they refer to as the Sun’s older cousin.
“A better understanding of tidal physics and the most advanced constraints we have on mass loss allow us to say that, as we know now, the Earth could be moving away from the Sun, contrary to what was previously predicted. However, given the current observational uncertainties in the rate of mass loss on the asymptotic branch of the giants, the final fate of the Earth remains uncertain,” added study co-author Stéphane Mathis from the CEA Paris-Saclay center to the research.
Even if the planet survived, it would remain a frozen and uninhabitable world after the Sun turned into a white dwarf.
