Post by Greg Goss Post by Kevrob Post by Cryptoengineer Post by ***@bid.nes
TL;DR: Volcanic greenhouse gases like hydrogen can keep a planet or
moon too far from a star for Earthlike insolation warm enough for
life. The Goldilocks Zone is now half again what it used to be. Yay!
Problem is, Earth is teetering at the *inner* edge of the Solar System's
Goldilocks zone, not the outer.
So, we have to get started on "planet moving" engines for when Sol
starts expanding, or find another place to keep our stuff!
Of course, you can hang the planet moving engines on some OTHER planet
and move the earth around by gravity. It wasn't until my third
read-through of Children of the State that I realized that Niven had
shoved a hot rocket up Uranus.
That's definitely the best option. If you have the time, you could expand
Earth's orbit *very* gradually, without creating noticeable effects on the
I recall one story in Analog where some aliens are intent on rescuing earth
by installing Very Large Engines in Antartica, and accelerating us along the
axis or rotation. However, the force was such as to cause Very Bad Things
to happen to the ocean and atmosphere.