A team of astronomers has discovered an Earth-like planet orbiting a star 4,000 light-years away from the solar system, potentially offering insight into Earth's distant future. The rocky planet, about the same mass as Earth, orbits a white dwarf in the constellation Sagittarius.
The discovery brings a glimmer of hope for Earth's survival as our sun enters its final phase. It suggests that Earth could potentially avoid being consumed by the expanding Sun, opening up possibilities for human migration into the outer solar system, with moons such as Europa, Callisto and Ganymede around Jupiter, or Enceladus near Saturn, possible refuges for future generations. .
What is a white dwarf?
A white dwarf is the remnant of a star after its nuclear fuel has been used up and its outer layers have been shed. It symbolizes the ultimate fate of the sun. The Sun will grow into a red giant when its nuclear fuel runs out, then shrink to become a white dwarf. The extent of the expansion will determine which planets in the solar system will be engulfed; Mercury and Venus are likely to be consummated. But what about the Earth?
In a study published in Nature Astronomy, researchers from the University of California, Berkeley, used the Keck Telescope in Hawaii to observe a system called KMT-2020-BLG-0414. The system contains a white dwarf star with an Earth-sized planet orbiting twice as far from the star as Earth is from the Sun. Next to the planet is a brown dwarf – a planet about 17 times the mass of Jupiter.
This finding supports the theory that as the Sun expands into a red giant, the loss of mass will push the planets into more distant orbits. This phenomenon could allow Earth to escape destruction. Jessica Lu, associate professor of astronomy at UC Berkeley, noted: “Whether life on Earth can survive during that (red giant) period is unknown. But the most important thing is certainly that the earth is not swallowed by the sun when it is swallowed up. becomes a red giant.”
Future of the Earth
“We currently have no consensus on whether Earth can avoid being engulfed by the red giant sun within six billion years,” said Keming Zhang, the lead author and former doctoral student at UC Berkeley who is now Eric and Wendy Schmidt. AI in Science Postdoctoral Fellow at UC San Diego.
“In any case, Planet Earth will only be habitable for another billion years, after which Earth's oceans will evaporate due to the runaway greenhouse effect – long before they are at risk of being swallowed by the red giant.”
Could humanity find refuge beyond Earth? As the sun expands into a red giant, the habitable zone in the solar system will shift outward toward the orbits of Jupiter and Saturn. Many of their moons, such as Europa and Callisto, could become ocean worlds that could support life. Zhang suggested, “Humanity could migrate there.”