THEIA

70% of the Moon is not the Moon.

2047. Shackleton Crater, Lunar South Pole.

Dr. Maya Chen is 1,847 meters down, 40 Kelvin in the shade, and 400 meters past her GO order when her drill hits something that cannot exist.

A vein of green.

Fo99 olivine. Pure forsterite. Holding water. Holding neon.

With an oxygen isotope signature of +0.08 and tungsten at ε182W -1.9 - a signature that hasn't existed for 4.51 billion years.

It's not lunar. It's not contamination.

It's Theia.

The planet that hit Earth. The planet that died to make us.

For fifty years we thought the Moon was Earth's daughter. Maya's data proves it was a murder - and a marriage. Earth and Theia vaporized into a donut of molten rock called a synestia, and from its outer edge, the first snow of a new world fell.

That snow was green. And it has been waiting in the dark ever since.

With 14 days of lunar night, a failing reactor, and NASA ordering her to stop, Maya has one chance to prove that the Moon's far side is Theia's face, the near side is Earth's - and that 50% of the atoms in your body are from another planet.

For fans of The Martian, Project Hail Mary, and Blindsight - a hard science thriller where every equation is real.

Every child born under the Moon is a child of two planets.