Free Astronomy Magazine September-October 2026

10 SEPTEMBER-OCTOBER 2026 ASTRO PUBLISHING gets, including far-away galaxies, some Earth-like planets around oth- er stars, and even asteroids poten- tially dangerous to Earth. Hainaut explains that “satellites, illuminated by the Sun, are much brighter than distant galaxies. When a satellite crosses what we observe, it makes a bright streak on our image, zapping whatever is behind it.” To compute the impact of this and other effects of satellite constella- tions on astronomical observations, Hainaut simulated the positions, motion and brightness of all present and planned satellite constellations. For the SpaceX satellite mega-con- stellation, he found that dozens of trails would appear in each image taken two hours into the night with ESO’s Very Large Telescope (VLT) at Paranal Observatory in Chile, repre- senting field-of-view losses of up to 28%. This assumes that the satellites would be faint enough not to be seen with the naked eye in good conditions. If they are just a little brighter, some instruments would be even more affected: for instance, point its beam directly at or near an observatory. Even so, the trail from a single mirror-satellite could spoil an observation with a camera like that of Rubin Observatory. With the full fleet of Reflect Orbital satellites in orbit, every image from such a camera would be lost when the satellites are illuminated by the Sun. However, it’s not just the criss-cross- ing paths of satellites that limit what we can observe: their light can pol- lute the entire sky. Satellites too faint to be seen di- rectly produce a veil of ‘diffuse’ light, while light from brighter satel- lites is ‘scattered’ in all directions as it passes through the atmosphere. Both contributions increase the overall brightness of the night sky. This study is the first to consider the impacts on astronomy due to the contribution of satellite constella- tions to background sky brightness, revealing the full extent of satellite light pollution. Very bright constellations like Re- flect Orbital would have a partic- ularly significant effect on back- T his image illustrates how sun- light scattered by Reflect Orbi- tal’s space mirrors would increase the overall brightness of the sky above ESO’s Very Large Telescope (VLT). The left image was captured with an all-sky camera on a moon- less night on 16 May 2026. North is up, and West is to the right. The domes hosting the four 8-m tele- scopes of the VLT can be seen to the top-right. The image to the right is a simulation showing how much brighter the sky would be with Re- flect Orbital’s full constellation of 50 000 mirrors. Even though the mirrors are not pointing directly at the ob- servatory, they still diffuse light side- ways, which is then further scatter- ed by the atmosphere. As a result, the sky would be up to three to four times brighter. [ESO/O. Hainaut] a camera like that of the US National Science Foundation’s Vera C. Rubin Observatory could have most of its images rendered unusable for sev- eral hours each night. Hainaut’s simulations assumed that no Reflect Orbital satellite would