Research Predicts Sun Will Destroy Earth in 5 Billion Years

Q: How does a distant dead star serve as a time machine to reveal the future of our own solar system?

A white dwarf such as WD 1856+534 acts as a natural preview of our solar system’s far future because it is the remnant of a Sun-like star that has already gone through the death our Sun is expected to experience in about 5 billion years. Astronomers can study the planet WD 1856 b, a Jupiter-sized world orbiting that dead star, to see what may happen after a star swells into a red giant and then collapses into a white dwarf. Our Sun is expected to follow the same path: it will expand dramatically, likely destroying Mercury and Venus and possibly Earth, then shed its outer layers and leave behind a white dwarf. Using the James Webb Space Telescope and spectroscopy, researchers measured WD 1856 b’s atmosphere, temperature and mass. They found methane, aerosols and unusual heat, evidence that the planet did not always orbit so close to the white dwarf. The leading explanation is that it survived the star’s violent red-giant phase from a safer distance, then migrated inward billions of years later. That makes the system a “time machine” in a scientific sense: it lets researchers observe a later evolutionary stage that our own solar system has not yet reached. The finding suggests that while Earth is unlikely to survive the Sun’s final expansion, some outer planets around Sun-like stars may endure, shift orbits and remain active long after their star has died.

Q: Earth will be destroyed in 5 billion years, but why might our oceans boil away 3 billion years sooner?

Earth’s oceans are expected to disappear roughly 2 billion years from now because the Sun will become steadily brighter long before it swells into a red giant and destroys the planet around 5 billion years from now. Astronomers estimate the Sun’s energy output rises by about 10% every billion years as it ages. That gradual brightening will heat Earth enough to trigger a runaway greenhouse effect. In that scenario, higher temperatures cause more ocean water to evaporate, and the extra water vapor traps even more heat, accelerating the warming until the oceans effectively boil away. Once large amounts of water reach the upper atmosphere, solar ultraviolet radiation can split water molecules into hydrogen and oxygen. The lightweight hydrogen then escapes into space, causing a permanent loss of water. Scientists think this is broadly similar to the process that helped leave Venus hot and dry. So the key difference is timing and mechanism. Earth’s final destruction is tied to the Sun’s death and red-giant expansion in about 5 billion years. The loss of the oceans comes much earlier because habitability ends when the Sun’s increasing luminosity overwhelms Earth’s climate system, not when the planet is physically engulfed. That is why studies suggest Earth may become uninhabitable billions of years before it is actually destroyed.

3 articles · Updated · The Elkhart Truth · Jul 1

New research says Earth is likely to be destroyed in about 5 billion years when the sun reaches the end of its life.
5 billion years is the study's central estimate for the sun's death, which the report identifies as the trigger for Earth's destruction.
Spectroscopy underpins the research approach, analyzing light passing through a planet's atmosphere during a transit by splitting it into constituent wavelengths.
The report points to Exoplanet observations as context for how scientists study planetary survival around dead or dying stars.