This page describes an image ESO's Very Large Telescope (VLT) at Paranal Observatory with a lunar halo
The Very Large Telescope on Cerro Paranal in Chile has four reflecting telescopes each with a primary mirror 8.2m across. In this image one dome is open and firing laser beams into the sky. These lasers create artificial stars in the sky that can be used to adjust the telescope optics to remove the blurring effect of the Earth's atmosphere. This process is known as adaptive optics.
In the sky the Moon is surrounded by a bright halo. This is caused by light from the moon reflecting inside ice crystals in the Earth's atmosphere.
Juan Carlos Muñoz-Mateos/ESO Credit Link
Related glossary terms:
Telescopes and Observatories
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