According to the giant impact hypothesis, Theia orbited the Sun, nearly along the orbit of the proto-Earth, by staying close to one or the other of the Sun-Earth system's two more stable Lagrangian points (i.e., either L4 or L5). Over time, however, Theia was eventually perturbed away from that relationship by the gravitational influence of Jupiter, Venus, or both, which resulted in a collision between Theia and Earth.
Computer modelling suggests that Theia was flying no faster than 4 kilometers per second (about 14,000 kilometers per hour) when it collided with Earth at an angle of approximately 45 degrees.
At first, it was thought that Theia had given Earth a light glancing blow, which had resulted in the ejection of many fragments of both the proto-Earth and Theia. It was thought that these fragments had either formed one body that eventually evolved into the Moon or formed two moons that eventually merged together to form the Moon. According to some stories, a direct collision between Venus and Mars would have resulted in the destruction of both planets and the formation of a second asteroid belt between the orbits of Venus and Mars.
On the other hand, data that was published in January 2016 implies that the impact was in fact a head-on collision, and that Theia's remains can be found both on Earth and on the Moon.
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