Earth’s Distant Future: We Might Have To Bail Out
Photo: Reuters via W.M. Keck Observatory Adam Makarenko Handout
WASHINGTON, DC (REUTERS) – The first rocky planet ever spotted orbiting a burned-out star called a white dwarf offers a glimpse of what may be in store for Earth billions of years from now – showing it is possible our planet might survive the death of the sun, albeit as a cold and desolate outpost in space.
The planet, with a mass about 1.9 times that of Earth, is orbiting the white dwarf about 4,200 light-years away from our solar system near the bulge at the center of the Milky Way galaxy, according to a study using data from Hawaii-based telescopes. A light year is the distance light travels in a year, about 5.9 trillion miles.
The white dwarf began as an ordinary star one or two times the mass of the sun. Its current mass is about half the sun’s. Stars with a mass less than eight times the sun’s end their lives as a white dwarf, the most common type of stellar remnant.
“It’s currently a freezing world because the white dwarf, which is in fact smaller than the planet, is extremely faint compared to when it was a normal star,” said University of California, San Diego astronomer Keming Zhang, lead author of the study published in the journal Nature Astronomy.
The sun, roughly 4-1/2 billion years old, is destined to become a white dwarf.
“At the end of our son’s life, it will puff up to enormous size – astronomers call it a red giant – and gently blow off its outer layers in a wind,” University of California, Berkeley astronomer and study co-author Jessica Lu said. “As our sun loses mass, the planets’ orbits will expand to larger sizes. Eventually, the sun loses all its outer layers and leaves behind a hot compact core. This is called a white dwarf.”
Astronomers have debated whether Earth – the third planet from the sun, with Venus the second and Mars the fourth – would be engulfed and destroyed when the sun expands during its red giant phase, estimated to occur seven billion years from now. It will become a white dwarf a billion years after that.
“Theoretical models disagree as to whether Earth could survive. Venus will most certainly be engulfed whereas Mars will most certainly survive. Our modeling shows that this planet very likely had a similar orbit to Earth before its host star became a red giant. It implies that Earth’s chances for survival may be higher than currently thought,” Zhang said.
As the sun ages and heats up, our solar system’s habitable zone would move outward. Earth will remain habitable for less than about a billion more years from now, by which point its oceans likely will have evaporated, Zhang said.
Does this mean certain doom for humankind – or whatever life still resides on Earth?
“We must migrate out of Earth prior to the one-billion-year time scale,” Zhang said.
By the time the sun becomes a red giant, certain large moons in the outer solar system like Jupiter’s Ganymede and Saturn’s Titan and Enceladus may offer a refuge, Zhang added.
VIJAY
/
Between now and the doomsday that is billions of years away, the earth most likely will be hit s a few times by a asteroid ending life as we know. Further, the earth will continue to cool to the extent the internal core will no longer be liquid ending magnetism and indirectly life here on earth.
October 8, 2024