Double Helix nebula. Spitzer Space Telescope (SST) infrared image of the Double Helix nebula. The nebula forms the spiral shape of a double helix, running from lower right to upper left. This is the same shape as found in DNA (deoxyribonucleic acid). This part of the nebula is 80 light years long. The dots in the image are red giant and supergiant stars. This nebula is 25,000 light years from Earth, near the centre of the Milky Way galaxy in the constellation of Sagittarius. It is thought that the nebula's shape has been formed by magnetic torsion forces from the supermassive black hole at the centre of our galaxy. The discovery of this nebula was announced in 2006.