Astronomers have discovered a distant, Earth-like planet that provides a chilling glimpse at how our planet could look billions of years from now.
This newly discovered planet was perhaps once habitable and used to orbit a star similar to how we orbit the sun.
However, its host star underwent a violent death at some point, causing the exoplanet to become untethered and drift further out in space.
Some studies suggest that out sun will begin its death process in about one billion years. When this time comes, our planet could meet a fate similar to this newfound planet.
Astronomers have discovered an Earth-like planet orbiting a white dwarf star 4,000 light-years away. Billions of years from now, our planet could look just like it
The new planet and its host star are located near the central bulge of the Milky Way galaxy around 4,000 light-years away from us, the equivalent of roughly 23 quadrillion miles.
It was first spotted in 2020, but a team of astronomers at the University of California, Berkeley recently took another look at this planetary system using the Keck 10-meter telescope in Hawaii.
Their study determined that this Earth-sized planet orbits a white dwarf star, or the dense, hot core of a star that has died.
Before the star died, this planetary system may have looked a lot like Earth orbiting the sun. And it’s not impossible that this planet could have supported life billions of years ago.
But today, this rocky, barren planet exists outside of the white dwarf’s habitable zone – the region around a star that is capable of sustaining life.
Our own sun will eventually go through this same death process. But we won’t be alive to see it. Studies suggest that our star has another billion years left in its life span.
But the sun’s death will eventually vaporize Earth’s oceans and double its orbital radius. And that’s only if the sun’s expansion doesn’t swallow our planet whole first.
As the sun enters its red giant phase – the final stage before death – it will inflate like a balloon, engulfing and incinerating Mercury and Venus.
As a star nears the end of its life, it begins inflating into the red giant stage. Any orbiting planets that are close enough during this process are swallowed by the sun’s expansion
Once the red giant stage ends, the star ‘dies’ and transforms into a white dwarf
Simultaneously, its shrinking mass will cause surviving planets – like Earth, perhaps – to widen their orbits.
This will offer Earth a slight chance of survival. But it is possible that our planet could be swallowed alongside Mercury and Venus during the sun’s red giant phase.
‘We do not currently have a consensus whether Earth could avoid being engulfed by the red giant sun,’ said lead author Keming Zhang, a postdoctoral fellow at the University of California San Diego, 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 – long before the risk of getting swallowed by the red giant,’ he added.
Eight billion years from now, the sun will begin its final transformation into a ‘dead’ white dwarf. Its outer layers will disperse, leaving behind a dense, glowing ball that is as big as Earth, but still has the sun’s original mass.
If Earth survives the sun’s red giant phase, it will have moved about twice as far from the sun as it is now. This new orbit will put it far outside the white dwarf’s habitable zone.
This grim picture of our planet’s future looks remarkably similar to the current state of this newly discovered planet.
‘This 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, associate professor and chair of astronomy at UC Berkeley, in a statement.
The research team published their findings today in the journal Nature Astronomy.
During a microlensing event, the background star’s brightness is amplified by a planetary system as they pass by each other
Astronomers first spotted this distant planetary system when it passed in front of a more distant star in 2020, magnifying its light by a factor of 1,000 times.
This is what’s called a ‘microlensing event.’ When a planetary system passes in front of a star, the gravity of the system acts like a lens to focus and amplify light from the background star.
Researchers at the Korea Microlensing Telescope Network analyzed that event and were able to determine that the system is comprised of a star roughly half the mass of our sun, an Earth-sized planet, and another enormous planet 17 times more massive than Jupiter.
They also concluded that the distance between the Earth-sized planet and the star is roughly equal to the distance between Earth and the sun.
But the team did not determine what type of star the planets were orbiting.
To answer that question, Zhang, Lu and their colleague Joshua Bloom – professor of astronomy at UC Berkeley – decided to take another look at this far-away planetary system using the Keck II 10-meter telescope in Hawaii.
They observed the system three years after the microlensing event occurred. Because of this timing, the background star was no longer magnified and had become faint enough that the ‘lensing’ star – the star that is part of the planetary system – should have been visible.
But Zhang and his colleagues saw nothing.
A normal star would have easily been seen, This fact, coupled with other known details about the lensing star, led the researchers to conclude that it could only be a white dwarf.
‘This is a case of where seeing nothing is actually more interesting than seeing something,’ said Lu.
This study not only offers a unique look at what the distant future of our planet and sun could look like, but underscores the value of closely studying microlensing events.
‘Microlensing has turned into a very interesting way of studying other star systems that can’t be observed and detected by the conventional means,’ Bloom said in a statement.
