Young planets in the Orion nebula, artwork. The brightest part of the Orion nebula (M42) is at top left. A large gas giant planet is seen in the sky from one of its moons. Its parent star is at lower left, and several rocky bodies of varying sizes are also seen. The Orion nebula contains numerous protoplanetary discs (proplyds), dense cocoons of gas and dust in which young stars and their associated planetary systems are forming. Planets form from the accretion of small particles of dust and rock over time, drawn together by gravitational attraction. The Orion nebula lies around 1600 light years away, making it the nearest starbirth region to Earth.