High on the mountaintop of Paranal in Chile,
dusk falls quietly over ESO’s Very Large Telescope (VLT).
In the darkness, four bright lasers shoot up into the sky
like something out of a science-fiction film.
These lasers help give astronomers a better view of stars and galaxies
far, far away.
Earth’s atmosphere is the biggest barrier
between ground-based telescopes and a sharp view of the night sky,
because turbulence causes stars to twinkle.
ESO built telescopes up here in the Atacama Desert
to exploit some of the clearest and darkest skies in the world.
Still not enough.
Cue a technological stroke of genius: adaptive optics.
Adaptive optics systems use bright stars
to measure atmospheric conditions.
This helps telescopes take sharper images.
But sometimes, there are no bright nearby stars.
So astronomers create them!
A powerful laser can make sodium atoms high in the atmosphere glow.
Instant artificial star!
In April 2016, four new stars arrived in the Paranal skies:
the 4 Laser Guide Star Facility was installed at the VLT.
Its four lasers are the most powerful ever used to create laser guide stars.
Creating multiple artificial stars
gives a better understanding of atmospheric conditions,
which leads to a better image.
This clever system is paving the way for the adaptive optics system
of the Extremely Large Telescope.
Transcription by ESO; Translation by —