According to Einstein’s theory of general relativity gravity affects light as well as matter. One consequence of this theory, based on the Principle of Equivalence, is that the light which escapes from a region with a strong gravitational field loses energy on its way, so that it becomes redder, a phenomenon known as the gravitational redshift. Quantifying this gives a fundamental test of Einstein’s theory of gravitation. Until now this test had been performed only on bodies in the nearby universe, but thanks to the use of a new experimental procedure scientists at the Instituto de

Since it started on October 3rd the conference “ Dark and Quiet Skies for Science and Society” has been discussing the consequences of artificial lighting at night (ALAN). But on Tuesday and Wednesday October 5th and 6th specialists from all over the world are discussing, on-line, solutions which reconcile the development of recent satellite constellations with scientific activity, and humanity’s right to enjoy the starry sky. Prof. Piero Benvenuto, the representative of the International Astronomical Union (IAU) on the UN Committee for the Peaceful Uses of Outer Space (UNCOPUOS) and one of

Yesterday saw the start of the Conference on Dark and Quiet Skies for Science and Society) organized by the United Nations Office for Outer Space Affairs (UNOOSA), the International Astronomical Union (IAU) and the Instituto de Astrofísica de Canarias (IAC) with the support of NOIRLab (The National Laboratory for Research in Optical and Infrared Astronomy of the National Science Foundation (NSF). As had been announced a few months ago, after last year’s Workshop, the aim of this new meeting is to focus on putting into practice the recommendations made in the exhaustive report which resulted

A central question regarding ultra-diffuse galaxies (UDGs) is whether they are in a separate category from low-surface-brightness (LSB) galaxies, or just their natural continuation toward low stellar masses. In this Letter, we show that the rotation curve of the gas rich UDG AGC 242019 is well fit by a dark matter halo with an inner slope that asymptotes to ~-0.54, and that such a fit provides a concentration parameter that matches theoretical expectations. This finding, together with previous works in which shallow inner profiles are derived for UDGs, shows that the structural properties of