About 7 billion years from now the Sun will have swelled into a red giant with a radius larger than Earth’s orbit. We’re doomed. Or so we thought.

A ray of hope has been thrown our way by astronomers who say that as the Sun expands it will lose a significant portion of its mass (perhaps almost a third) in the form of a solar wind that is blown away. And as the mass drops, the radius of Earth’s orbit should increase.

That complicates things so Robert Connon Smith from the University of Sussex and a pal took on the task of determining whether this new thinking means Earth will survive or not.

And the answer is…cue drum roll.. that the planet will still be engulfed.

But they offer another ray of hope. Earth’s angular momentum around the smaller Sun need only be increased by 8 per cent to avoid engulfment and that, says Smith, could be achieved by engineering a series of asteroid swingbys that gradually lift us into a wider orbit.

If we start planning now, there’s hope for Mother Earth yet.

Ref: arxiv.org/abs/0801.4031: Distant Future of the Sun and Earth Revisited

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