Few people would want to know the time and nature of their own demise, but for planet Earth, its fate is sealed. In five billion years it will likely be engulfed by our own Sun and devoured by a stellar inferno.

Now, for the first time, astronomers have seen what that could look like because another planet in the Milky Way has been seen getting swallowed by its own star.

Experts from Harvard, Caltech and MIT were studying a star 12,000 light years away which was entering its red giant phase at the end of its life and swelling in size.

As the star expanded in an attempt to extend its lifespan because it was running out of fuel it started dragging an orbiting planet towards it, before engulfing it.

Over a ten-day period the scientists saw the star become 100 times brighter than usual and analysis showed similarities to when two stars merge.

However, the brightness of this event was only one thousandth of the strength of a dual-star merger, leading the team to conclude with various computer models that the star had engulfed a large planet, roughly the size of Jupiter.

After ten days of exceptional brightness the star cooled down and astronomers saw the brightness fading over the next six months. Our own Sun, whose warmth and gravity allowed for life to flourish, will one day do the same to us but Earth’s fiery downfall will occur in around five billion years time.

“We are seeing the future of the Earth,” study lead author Dr Kishalay De from MIT, said of the findings. “If some other civilization was observing us from 10,000 light years away while the Sun was engulfing the Earth, they would see the sun suddenly brighten as it ejects some material, then form dust around it, before settling back to what it was.”

100-fold spike in brightness
He adds that he was looking at data from the Palomar Observatory in California when he saw the 100-fold spike in brightness which was, he says, “unlike any stellar outburst I had seen in my life”.

A year later he studied the same event with infrared data, not visible light. “That infrared data made me fall off my chair,” he says. “The source was insanely bright in the near-infrared.”

The scientific findings of Dr De are a key breakthrough in understanding planetary dynamics but are a harbinger of doom for Mercury, Venus, and probably also Earth.

“I think there's something pretty remarkable about these results that speaks to the transience of our existence,” said Ryan Lau, co-author on the study from the NOIRLab, said.

“After the billions of years that span the lifetime of our Solar System, our own end stages will likely conclude in a final flash that lasts only a few months.”

The study is published in the journal Nature, and Dr Smadar Noaz, an astronomer at UCLA, said in an accompanying article that “gravitational interactions between a star and a planet in close orbit around it can also slowly drive the planet to its demise”.

“As a star exhausts its core hydrogen fuel, it expands and becomes a sub-giant. At this stage, it will start to engulf its nearby planets — in a few billion years, the Sun will undergo this process.”

Dr Noaz added that more observations are needed of the planet-swallowing star seen in this study to understand more about similar events and learn what leads to them occurring.