Free Astronomy Magazine January-February 2026

17 JANUARY-FEBRUARY 2026 ASTRO PUBLISHING tem to correct the blur caused by the Earth’s at- mosphere — with ad- vanced state-of-the-art sensors and deformable mirrors. Until now, for the VLTI, adaptive-optics corrections have been done by pointing to bright reference stars that need to be close to the target, limiting the number of objects we can observe. With the installation of a laser at each of the UTs, a bright artificial star is created 90 km above Earth’s surface, enabling the correction of atmos- pheric blur anywhere on the sky. This unlocks the whole southern sky to the VLTI and enhances its observing power dra- matically. “This opens up the instru- ment to observations of objects in the early distant Uni- verse, such as a quasar we studied, where we resolved the hot, oxygen emitting gas very close to the black hole,” says Taro Shimizu, an MPE as- tronomer who is a mem- ber of the instrument consortium. With lasers on the tele- scopes used by the VLTI, astronomers will be able to study distant active galaxies and directly measure the mass of the supermassive black holes that power them, as well as observe young stars and the planet-forming discs around them. The VLTI’s improved ca- pabilities will drastically increase the amount of light that can travel “A big goal of GRAVITY+ is to allow for deep ob- servations of faint tar- gets,” explains Julien Woillez, an ESO as- tronomer and GRAVITY+ project scientist. This increased ability to detect dimmer objects will allow observations of isolated stellar black holes, free-floating plan- ets that do not orbit a parent star and stars clos- est to the Milky Way’s supermassive black hole Sgr A*. A first target for the GRAVITY+ and ESO teams at Paranal performing test observations using the new lasers was a clus- ter of massive stars at the centre of the Tarantula Nebula, a star-forming region in our neighbouring galaxy the Large Magellanic Cloud. These first observations revealed that a bright object in the nebula, thought to be an ex- tremely massive single star, is actually a binary of two stars close together. This showcases the stun- ning capabilities and sci- entific potential of the upgraded VLTI. This improvement is be- yond just an update and was first envisioned dec- ades ago. The laser sys- tem was suggested in the final report of the “Very Large Telescope Project” in 1986 before the VLTI even existed: “If it could work in practice, it would be a break- through,” the report stated. Now this break- through is a reality. T his photograph, taken from the platform at Paranal Observa- tory in early November, shows lasers pointing in the direc- tion of the Tarantula Nebula as ESO’s Very Large Telescope Interferometer (VLTI) observed this target. The observations were conducted as part of commissioning activities related to the GRAVITY+ upgrade to the VLTI, which here is combining light from four eight-metre telescopes. With the installation of a laser at each of the telescopes, a bright ‘fake’ star is created 90 km above Earth’s surface by each laser, enabling the correction of atmospheric blur. [ESO/A. Berdeu] T his animation, provided by the Max-Planck Institute for Ex- traterrestrial Physics (MPE), shows the path of light inside GRAVITY+, an instrument and a large and complex upgrade to ESO’s Very Large Telescope Interferometer (VLTI). As light trav- els from a cosmic source into the individual Unit Telescopes of the VLT, and then inside the VLTI tunels where it's combined, lasers are project from each of the telescopes. The lasers are each used to create an artificial star, which astronomers use to measure and then correct the blur caused by Earth's atmos- phere. [MPE/GRAVITY+ Collaboration] through the system, making the fa- cility up to 10 times more sensitive. ! https://www.eso.org/public/unitedkingdom/videos/eso2519c/