Face to face with the Moon

Few people have ever viewed the Moon through a telescope as monumental as ESO’s Very Large Telescope (VLT). Astronomers at Paranal Observatory in Chile recently enjoyed this unique opportunity when one of the telescope’s instruments, VIMOS (VIsible Multi-Object Spectrograph), was decommissioned to free up a space at the UT3 telescope for  the upcoming CRIRES+ (the CRyogenic InfraRed Echelle Spectrograph Upgrade Project).

VIMOS was astonishingly productive; the spectrograph studied thousands of distant galaxies seen at a time when the Universe was only at a third of its current age, and mapped their distribution and physical properties. The sensitive instruments used by the VLT, including VIMOS, are designed to image dim objects billions of light-years away, and therefore objects as near and bright as our planet’s moon easily completely saturate them with far too much light. But when VIMOS was decommissioned after 16 years of service, the astronomers stationed at Paranal took advantage of the unusual opportunity to utilise a telescope focal station with no instrument attached.

Instead of looking into deep space, they pointed and focused UT3, one of the VLT’s Unit Telescopes — the VLT has four, each with a mirror measuring 8.2 metres across — on the Moon. To create this mesmerising image, the twilight Moon was projected onto a semi-transparent screen, resulting in an intricately detailed display of the myriad crags and craters scattered across its surface. This incredible view was enjoyed by numerous astronomers including Stefan Ströbele, the Adaptive Optics engineer seen in this image.