As more comets arrive and pellets pelt down, the moon spins faster. From its lazy “day” cycle of 28 days, it speeds up to a 60 hours—close enough to Earthlike, as they say, for government work.
For most of its life, the moon’s axial tilt has been a dull zero, robbing it of summers and winters. But if they are angled just so, the incoming ice nuggets can tilt the poles while shortening the days. From such simple mechanics we conjure seasons.
All told, we’ll need about 100 comets the size of Halley’s, which will bring water and carbon dioxide, with smidgens of methane and ammonia. We’ll need nitrogen, too, and some magic from the biochemists, who will pepper the moon’s old, gray rocks with blue-green algae that can exhale oxygen.
For centuries the moon’s dark plains had carried humanity’s imposed, watery names: Tranquility, Serenity, Crises, Clouds, Storms. Now, thanks to the “rain” of iceteroids, these lowlands of aged lava catch the rains and fatten muds into ponds, lakes, true seas. After billions of years, the ancient names come true.
Genetically engineered plants will create the first greenery. Like Earth's tropics now, at the moon’s equator heat drives moist gases aloft. Cooler gas flow from the poles to fill in. The high wet clouds skate poleward, cool, and rain down.
On Earth, such currents are robbed of their water about one-third of the way to the poles, creating the worldwide belt of deserts. Not so on the moon. The new world has no chains of deserts, just one simple circulating air cell grinding away in each hemisphere. Moisture forges climate. Northerly winds sweep poleward, swerving toward the west to make the occasional mild tornado.
The moon, once “the lesser light that rules the night,” now shines five times brighter, casting sharp shadows on Earth. Because of the reflection of the seas, when the alignment is right, people on Earth’s night side gaze up at Earth's image.
The moon has no soil, only the damaged dust left from 4 billion years beneath the solar wind's anvil. Making soil from gritty grime is work best left to the biologists. Our moon can brew its own, in fast-forward. Bioengineered minions can till the dirt, massage the gases, build an ecology.
The gray sphere that the Russians may make into the realm of strip miners and rugged, space-suited loners can become a thin-aired habitat, in time—a world where humans might breathe free. We may walk alongside strange new life forms created by bioengineers. Perhaps we will see bovine gas-bags that patrol the skies, spindly zigzagging trees, birds swooping like manta rays, spindly ropes with shimmering green leaves bigger than buildings. Our moon can become not a replica of Earth, but an exotic realm we shape as we like, and come to love.
Sunsets will seem to happen in slow motion, the full pallet of pinks and crimsons and rouge-reds lingering for an hour. Pearly, blue-dot Earth will eclipse that sun, punching a dark hole in the middle of the day, for some on the half we’ll call Nearside. The deep air will covet heat, making the moon much like a cloudy Florida. In the one-sixth gravity, humans can fly, with flaps on arms and feet. At last we will be at one with the birds—big rude beasts who will challenge us among the thick decks of pewter cloud.
This exotic Floridalike globe with the land mass of Asia will have mostly cloudy days. It’ll be warmer, too, from greenhouse effects. Earth will still hold sway over a moon revolving much faster, making its presence felt even if you can’t see it most of the time. The tides will be 20 yards high—and so can be surfed. With lesser gravity, a boarder can skate over hundreds of miles, a daylong ride. Of course, when that tide slides up the shore of a lunar lake, there’ll be plenty of tourists scampering away from it.
This sobering step to a higher level could mark a defining role for an emergent humanity, securing its future with a new, distant habitat. We may finally become, millennia after the Old Testament commanded, true stewards of the Earth—and no doubt, more.
This article is part of Future Tense, a collaboration among Arizona State University, the New America Foundation, and Slate. Future Tense explores the ways emerging technologies affect society, policy, and culture. To read more, visit the Future Tense blog and the Future Tense home page. You can also follow us on Twitter.