Ghostly galaxies above the VLT

Floating in the sky above two of ESO’s Very Large Telescope (VLT) Auxiliary Telescopes are a pair of ethereal shapes. These are the Large and Small Magellanic Clouds — two of the 50 or so satellite galaxies that orbit our more massive Milky Way.

Despite being small compared to the Milky Way, the Magellanic Clouds still contain billions of stars. The Large Magellanic Cloud, in the bottom-right of the image, has a diameter of 14 000 light-years, and the Small Magellanic Cloud in the top-centre is 7000 light-years across. At distances of about 160 000 light-years and 200 000 light-years respectively these satellite galaxies are much closer to the Milky Way than our nearest major galaxy, Andromeda, 2.5 million light-years away, making them some of our closest neighbours.

The faint red emission in the sky is called airglow, and it's light naturally emitted by atoms and molecules high up in the atmosphere, oxygen in this case.

These ghostly galaxies can only be seen in the southern hemisphere, in skies that are unpolluted by light from cities. This is one of the reasons that ESO operates the VLT in the remote Chilean Atacama Desert — so that we can study such beguiling objects as the Magellanic Clouds.