The Earth could survive the Sun

We all learned in school that our planet would be swallowed up by the sun in a few billion years. Well, it’s not so sure: we have just seen a planet which escaped this disastrous fate, and which floats nicely around a dead star (white dwarf).

Vincent Nouyrigat, editor-in-chief of the magazineEpsiloongives us a little hope today regarding the planned death of our Earth, if the Sun were to transform into a red giant, in a few billion years…

franceinfo: American astrophysicists have detected a planet similar to Earth, which survived the death of its star, can we nourish this hope?

Vincent Nouyrigat: Yes, you may have been traumatized at school by your physics teacher who told you that our planet is doomed to disappear in 5 or 6 billion years: the Sun will consume all its hydrogen, it will swell, become 100 times larger, transform into a red giant and engulf, even tear apart, the Earth. In short, the end of the world explained to children.

Well, this disastrous scenario is perhaps avoidable: researchers from the University of California have detected 4000 light years from us, a rocky planet comparable to Earth, apparently intact, revolving around a corpse of star – what researchers call a white dwarf.

But how is this possible?

Astrophysicists believe that this planet originally orbited its star at a distance comparable to that which currently separates the Sun from Earth.

But as its star aged, burned up its hydrogen and lost mass, the gravity it exerted diminished. Which allowed this lucky planet to move away, and escape the bloated red giant – researchers observed that it was now twice the distance from Sun to Earth, so it migrated.

In our solar system, we are almost sure that Mercury and Venus will not survive, they are too close to the sun. But researchers are now saying that the Earth has a chance of surviving!

And could life persist?

Yes, but not necessarily on Earth. We must remain lucid: in a billion years, under the furnace of the red giant in formation, our oceans will boil and terrestrial life should become extinct here – even if our very distant descendants will perhaps have the opportunity to migrate towards the icy Moons of Saturn or Jupiter, which could at that time become frequentable.

Once the Sun dies, transformed into a white dwarf, a very small star emitting a very faint bluish-white light, things become complicated. But there is still hope. The pale glow of a white dwarf would indeed be sufficient to sustain life in its very close suburbs – about 1% of the current Sun-Earth distance.

Two years ago, the British observed a planet evolving in the habitable zone of a white dwarf; simulations even show that the remains of shredded planets could clump together and form a new generation of planets around these star corpses, planets where life could eventually flourish. Maybe the end of the world isn’t so sad…