Astronomers have pinpointed when Earth will be destroyed: in about five billion years, when the sun dies. The research, led by the University of St Andrews and published in the journal Nature, used the James Webb Space Telescope to study a Jupiter-sized exoplanet orbiting a white dwarf, offering a preview of our solar system's fate.
Sun's Death Will Destroy Earth
The sun will eventually run out of hydrogen fuel in its core, swelling into a red giant star more than 100 times its current size. This expansion will engulf and destroy Mercury, Venus, and possibly Earth. After shedding its outer layers, the sun will end its life as a white dwarf star. The study's lead author, Dr Ryan MacDonald from the University of St Andrews, described the research as 'like using a time machine to peer into the distant future of our Solar System.'
The Oddball Planet WD 1856 b
The team focused on exoplanet WD 1856 b, discovered in 2020, which orbits the white dwarf WD 1856+534 about 80 light-years from Earth. Despite being roughly the size of Jupiter, it orbits a star the size of Earth, making the planet seven times larger than its star. Its orbit is extremely close—50 times closer than Earth's orbit around the sun—raising questions about how it survived the star's death.
Using the James Webb Space Telescope, the researchers observed a 'grazing transit' where the top of the planet partially overlapped the star. This yielded data on the planet's mass (between four and 11 times that of Jupiter) and temperature (around 400 Kelvin, or 126°C), which is about 240 degrees hotter than expected if only heated by the white dwarf. The excess heat suggests residual energy from being engulfed by the red giant or during an inward migration.
Implications for the Solar System
Dr MacDonald noted: 'We're used to looking back in time when we use telescopes, but this is the first time we have been able to look forward to what might happen to the outer planets around the remnant of a Sun-like star.' The study helps predict the fate of more distant planets like Jupiter and Saturn, which are gas giants mainly composed of hydrogen and helium. While Earth's destruction seems certain, the future of these outer planets remains uncertain.
