Antennae Galaxies. Image: Hubble/European Space Agency.
This image of the Antennae Galaxies, captured by the Hubble Space Telescope, shows these two spiral galaxies locked in a chaotic embrace.
The pair — also known as NGC 4038 and NGC 4039 — were once separate spiral galaxies similar to the Milky Way, but have been colliding for hundreds of millions of years. This violent collision causes stars to be thrown out of the galaxies, creating a streaming arc between the two. The galaxies get their name from the antenna-like projections of stars and gas which stream out into space.
The clouds of pink and red gas surround the galaxies’ blue star-forming regions. The rate of star formation is so high that the Antennae Galaxies are said to be in a state of starburst, a period in which all of the gas within the galaxies is being used to form stars. This cannot last forever and neither can the separate galaxies; eventually the nuclei will coalesce, and the galaxies will form one large elliptical galaxy.