The “White Dwarf” Mystery: What Earth Will Look Like After Billions of Years

2nd October 2024

2 minutes read

The "White Dwarf" Mystery: What Earth Will Look Like After Billions of Years

A recent scientific study published in the American journal Nature Astronomy revealed findings about the first rocky planet observed orbiting a star nearing the end of its life, known as a “white dwarf.” This discovery provides a glimpse of what Earth might become in billions of years.

The study, using data from telescopes in Hawaii, reported that the planet, which has a mass 1.9 times that of Earth, orbits a white dwarf located approximately 4,200 light-years from the solar system, near the center of the Milky Way galaxy.

It noted that this star “began its life as a normal star, one or two times the mass of the Sun, but its current mass is about half that of the Sun.” It is known that stars with masses less than eight times that of the Sun turn into white dwarfs at the end of their lives, making this the most common type of stellar remnant.

The study indicated that the planet orbited the star before its demise, at a distance that likely placed it in the “habitable zone,” meaning it was neither too hot nor too cold, allowing liquid water to exist on its surface, potentially supporting life.

Initially, the planet orbited at a distance similar to that of Earth from the Sun. After the star’s death, this distance increased by about twice the original distance.

Kaiming Zhang, an astronomer at the University of California and the study’s lead author, said it is currently “a frozen world because the white dwarf, which is actually smaller than the planet, is extremely faint compared to when it was a normal star.”
He added: “The Sun, which is 4.5 billion years old, is expected to turn into a white dwarf as well.”

Jessica Lu, an astronomer at the University of California, Berkeley, and a co-author of the study, explained: “At the end of its life, our Sun will expand into a giant red star, losing its outer layers gradually. As the Sun loses mass, the orbits of the planets will grow larger. Eventually, the Sun will shed all its outer layers and leave behind a dense, hot core known as a ‘white dwarf.'”

Astronomers disagree on whether Earth will be engulfed and destroyed when the Sun becomes a red giant. Estimates suggest this will happen in about seven billion years, and the Sun will turn into a white dwarf a billion years after that.

Zhang clarified that theories differ on whether Earth will survive, but it is almost certain that Venus will be engulfed, while Mars may survive.