Future fate of the Earth seen as planet is engulfed by its parent star

For the first time, astronomers have spotted a star in the act of swallowing a planet, a fate that will eventually come to the Earth. 

In May 2020, a star 12,000 light years away in our galaxy suddenly appeared 100 times brighter over the course of 10 days, then mostly faded back to normal over the next six months.

Stars can suddenly brighten for a number of reasons; they may explode as supernovas, collide with another star, or have extra activity in their cores. But a new study published in the journal Nature found this event was different because the star seemed to get cooler in the months after, not hotter, which is the norm. 

Using a combination of telescopes including the Zwicky Transit Facility (ZTF) in California, where scientists first picked up the signal, and the Keck Observatory in Hawaii, the researchers were able to examine the star in different wavelengths of visible light to analyze its chemical composition. They found signs of molecules that can only exist at cold temperatures, which one of the study’s authors described as “peculiar.” 

After observing it in the infrared portion of the light spectrum where colder objects shine more brightly, they suspected the star must have been ejecting gas that condensed into a cold dust cloud. 

With the help of NASA’s NEOWISE space telescope, the researchers were able to estimate the energy the star released following its initial brightening. That helped them determine that the object gobbled up by the star was no more than 10 times the size of Jupiter.

WATCH | An artistic representation shows a star absorbing a planet.

A star swallowing a planet is thought to be a common event in our galaxy, especially when stars reach the end of their lives. Our sun, for example, will eventually run out of hydrogen fuel in its core, causing it to collapse, which will increase the pressure within it until it begins to burn helium at higher temperatures. This will push the surface of the sun outwards until it swells into a red giant star. 

As a red giant, the sun will be about the size of the orbit of the Earth, possibly bigger, which means Mercury, Venus and Earth will all be consumed.

One can imagine a scenario of the demise of our planet as seen from the surface. This late stage of the sun’s life would be a spectacular sight, although you wouldn’t want to be here to witness it.

The sun would grow to an enormous wall of red, filling the entire sky from horizon to horizon. Life would be extinguished as temperatures rise, scorching the ground until the oceans boil away, engulfing the whole planet in clouds that would soon be burned off by solar radiation, giving the Earth a long comet-like tail. As the Earth plunges into the sun’s searing atmosphere, mountains melt into valleys until what was once a living blue Earth becomes a dusty mist surrounding a dying star.

Thankfully, that grizzly end of the world scenario is not expected to happen for another five billion years. Although life on Earth could be extinguished a billion or so years earlier as the sun goes through the first stages of its demise.

At least that’s the theory.

Now that they’ve witnessed a planet being consumed by a star, astronomers hope to see more events like it to get a better understanding of exactly how planets — including our own — will eventually meet their fiery ends.