Right now, two NASA probes are entering a mysterious region of space to look for remains of an ancient planet which once orbited the Sun, not far from Earth. If they find anything, it could solve a major puzzle – the origin of the Moon.
The name of the planet they’re looking for is called Theia. It’s a world we’ve never actually seen but some researchers believe it existed 4.5 billion years ago—and that it collided with Earth to form the Moon.
About 4 billion years ago, a Mars-sized planet crashed into Earth. Debris from the collision, a mixture of material from both bodies, spun out into Earth orbit and eventually formed our Moon. It’s a good theory, but it leaves one awkward question unanswered: Where did the enormous planet come from?
The researchers believe it came from a Sun-Earth ‘Lagrange point’, a broad region of space, 50 million kilometres wide, where the pull of the Sun and Earth cancel each other out. Computer models show that enough early solar system material could have collected here to form Theia, which was later nudged out of position by the increasing gravity of other developing planets like Venus and sent on a collision course with Earth.
Right now, the two probes are closing in, cameras ready. We might not see anything but if we discover lots of asteroids around these Lagrange points, and later missions discover the asteroids have the same composition as the Earth and Moon, it will support the giant impact theory.
Let the hunt begin!
Dave Reneke
www.skyandpsace.com.au
