Astronomers wonder about the future of the Earth when the Sun reaches the end of its life. A recent study, based on the observation of a planet similar to ours near a dying star, offers a glimpse of what our world could become in 8 billion years.
What will become of the Earth when the Sun reaches the end of its life? Will it still be habitable? To answer these questions, researchers analyzeda planet orbiting near a dying star.
Like all stars, the Sun will go through several stages during its life. In 5 billion years, it will become a red giant. This stage occurs when most of the hydrogen in the core is used up. This contracts, while the outer layers of the star expand. When that day comes, it will swallow up the planets around it. Mercury and Venus will certainly be among its victims. Nothing is sure for Earth. If it survives, what will become of it afterwards, when the Sun is no longera white dwarfthe final stage of life before complete cooling?
To find out, researchers were interested in KMT-2020-BLG-0414. Discovered in 2020, this Earth-like planet is located 4,000 light years away of it, within the Milky Way. The sphere is in orbit around a white dwarf at a distance of one to twice that of the Earth from the Sun. She is not not in the habitable zonebut may have supported life when its star was in the same phase as the current Sun.
“It is unknown whether life can survive on Earth during this (red giant) period. But the most important thing is certainly that the Earth is not swallowed by the Sun when it becomes a red giant”said Jessica Lu, associate professor and chair of the astronomy department at the University of California, Berkeley. “This system discovered by [Keming Zhang, auteur principal de l’étude] is an example of a planet – probably a planet similar to Earthinitially in an orbit similar to Earth – which has survived the red giant phase of its host star.”
Disappeared oceans and a doubled orbit
What KMT-2020-BLG-0414 and other studies tell us is that our planet will be habitable for about a billion years. Ensuite, “the oceans will be vaporized by the uncontrollable greenhouse effect – well before the risk of being swallowed up by the red giant”explains Keming Zhang, astronomer and Eric and Wendy Schmidt AI postdoctoral researcher in Science at the University of California, San Diego (United States).
If she escapes the hungry Sun, its orbit may change as it transforms. It will probably end up in an orbit twice as big as its current size. For what ? Because the Sun “will eventually inflate like a balloon larger than Earth’s current orbit” forcing it to move away, indicates the University of California in a press release.
The satellites of Jupiter and Saturn, habitable in the future?
Unlike our planet who will be become uninhabitablethe moons of Jupiter and Saturn could be a refuge for lifewhen the Sun reaches the red giant phase. Europa and Enceladus are currently frozen but they will become aquatic worlds during the last years of our sun’s existence. And we know it: water is the essential element for all forms of life.
Sources :
- Zhang, K., Zang, W., El-Badry, K. et al. An Earth-mass planet and a brown dwarf in orbit around a white dwarf. Nat Astron (2024). https://doi.org/10.1038/s41550-024-02375-9
- “This rocky planet around a white dwarf resembles Earth — 8 billion years from now”, communiqué de presse de the University of CaliforniaSeptember 26, 2024.
- “Astronomers spot a possible ‘future Earth’ — 8 billion years into its future”, LiveScienceSeptember 26, 2024.
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