Earth's end coming soon? New research offers chilling insights into when & how our planet will cease to exist
By Shweta Kumari | First Published Sep 28, 2024, 8:00 AM ISTIn a groundbreaking discovery, astronomers from the University of California, Berkeley have identified an Earth-sized planet orbiting a white dwarf star approximately 4,000 light-years away in the Milky Way galaxy.
In a monumental discovery that foreshadows Earth’s distant destiny, astronomers have identified a planet orbiting the dying remnants of its star — a haunting mirror of what might become of our world billions of years from now.
The newly discovered planet, which once likely sustained life, is located around 4,000 light-years from Earth, near the central bulge of the Milky Way galaxy. This rocky world now floats untethered, its star having undergone a violent death, casting the planet into the cold depths of space.
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Astronomers from the University of California, Berkeley, who took a fresh look at the planetary system with the powerful Keck 10-meter telescope in Hawaii, believe this distant exoplanet was once part of a thriving solar system, much like our own.
Their findings revealed that the Earth-sized planet orbits a white dwarf — the dense, smoldering core of a star that has long since burned out. Before its catastrophic demise, the planetary system may have resembled our own, with the planet once bathed in warmth and perhaps even capable of harboring life.
But the star’s death transformed this planet into a desolate, lifeless rock, now orbiting far outside the "habitable zone," the sweet spot where conditions might still support life.
Keming Zhang, lead author of the study and postdoctoral fellow at UC San Diego, warns that this grim fate could await our planet as well. "We do not currently have a consensus whether Earth could avoid being engulfed by the red giant sun," he explained in a statement. “In any case, planet Earth will only be habitable for around another billion years, at which point Earth's oceans would be vaporized by runaway greenhouse effect.”
Indeed, as Zhang and his colleagues outline, the sun is not immortal. Our star is expected to begin its slow death in about a billion years, when it will inflate into a red giant, devouring Mercury and Venus in a fiery blaze. Earth may escape this inferno — for a while — but it will not be spared. If the sun’s expansion doesn’t swallow our planet whole, the ensuing changes will render Earth uninhabitable. Our oceans will evaporate, and the planet will drift further from the sun, doubling its distance from its now-dead star.
"The system that Keming's found is an example of a planet — probably an Earth-like planet originally on a similar orbit to Earth — that survived its host star's red giant phase," said co-author Jessica Lu, professor of astronomy at UC Berkeley.
The team's groundbreaking research was published in Nature Astronomy, shedding light on not just the eventual fate of our own solar system, but also on how planetary systems across the universe evolve after the death of their host stars.
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This extraordinary system was first discovered during a rare cosmic phenomenon called a "microlensing event." In 2020, astronomers witnessed the planetary system pass in front of a more distant star, causing the foreground planet's gravity to magnify the background star’s light 1,000 times. By analyzing the light, researchers deduced the presence of an Earth-sized planet and another massive planet orbiting a star about half the mass of our sun.
However, the nature of this star remained elusive. To uncover the truth, Zhang, Lu, and fellow astronomer Joshua Bloom turned to the Keck II telescope for answers. Observing the system three years after the event, they expected to see the "lensing" star — but were met with a puzzling void.
A normal star should have been clearly visible. The absence of any light led them to conclude that the star in question could only be a white dwarf, as only such an object would remain invisible under those circumstances.
"This is a case of where seeing nothing is actually more interesting than seeing something," Lu remarked.
Their discovery provides not only a sobering preview of Earth’s future, but also an exciting testament to the potential of microlensing in revealing secrets of distant star systems. As Joshua Bloom emphasized, "Microlensing has turned into a very interesting way of studying other star systems that can't be observed and detected by the conventional means."
In the end, the fate of this distant, barren planet offers a stark reminder of the fragility of life and the inevitable evolution of the cosmos. While our time on Earth is finite, studies like these keep our eyes turned skyward, searching for answers about the universe’s past — and perhaps, our own future.
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