The European Southern Observatory has released a breathtaking photo of the Milky Way shining over the Paranal Observatory in Chile, as lasers create artificial “guide stars” in the pristinely dark sky above.
What is it?
Stars, satellite streaks, galaxies and the tools that astronomers use to observe them are all on display in a single photo captured by Chilean astrophotographer Alexis Trigo, released by the European Southern Observatory (ESO) on Feb. 9.
Each of the four “Unit Telescopes” looming in the background houses an 8.2-meter primary mirror that, in conjunction with other cutting edge instruments, is capable of surveying distant exoplanets and the deep universe alike in incredible detail.
The UTs — named Antu, Kueyen, Yepun and Melipal from left to right — are capable of working independently, or in concert as the Very Large Telescope. The 1.8-meter auxiliary telescope in the foreground is, in reality, much smaller than its UT cousins and can be repositioned on rails to bolster the light-gathering capabilities of the VLT as needed.
Why the lasers?
The four lasers firing from UT-4 (Melipal) to the right of the screen are designed to penetrate 56 miles (90 kilometers) into Earth‘s upper atmosphere where they strike sodium atoms, causing them to glow in order to create artificial “guide stars”. By tracking these particles, adaptive optics technologies mounted on the VLT’s primary mirrors are able to correct for the blurring and distorting effect of Earth’s atmosphere in real time!
Melipal has been using its guide star lasers to great effect since they were installed back in 2016. The other three Unit Telescopes were equipped with lasers of their own in December 2025, in an effort to support the Very Large Telescope Interferometer (VLTI and GRAVITY+ ) instruments. Now, the veteran observatory is able to correct for atmospheric distortion more effectively, while guided by a constellation of bespoke artificial stars.
Check out our explainer article on the VLT to find out more!
