Central Heat — David Dvorkin

The disk, thin and gray, was undoubtedly alien. Scientists gathered on the moon to track its enigmatic course through space. But their fascination soon turned to horror...

FOR THE DISK PASSED BEFORE THE SUN AND BLOTTED IT OUT. COMPLETELY.

On Earth a new ice age began. Billions perished in the bone chilling cold. The lucky few escaped underground--doomed to an airtight existence near the blazing heart of the world.

Now, far beneath the unnatural cold of a once-green world, Earth's last survivors plan to resurface. And when they do, they will reclaim a lost technological legacy... and prepare for the aliens' return.