E.(L).T. phone home

It’s spooky season, and ESO’s Extremely Large Telescope (ELT) got the memo for this Halloween-inspired Picture of the Week. A full moon rises up from behind Cerro Armazones, the ELT’s perch in the Chilean Atacama Desert, where construction of the monster telescope is underway.

In this image –– a throwback to a famous scene in E.T. –– we see the steel skeleton of the telescope dome eerily illuminated under the moonlight. It now stands at a towering 80 metres high; when completed, the whole structure will rotate 360 degrees to observe the night sky, all while weighing 6100 tonnes — about as heavy as 1 500 000 pumpkins.

This ghostly image was captured on 28 October 2023, from around 20 kilometres away close to the entrance to ESO’s Paranal Observatory. It’s not every day that the Moon is positioned so perfectly behind the mountaintop, so an event was carefully planned by the Paranal Photo Club to capture the moment. Not only does the Moon cycle through different phases — new moon, first quarter, full moon and last quarter — as it orbits around Earth every 27.3 days, but its position on the horizon and the time at which it rises change over time as well.