Abstract

The emergence of the three-dimensional structure of the cosmic web over the history of the Universe displays very distinctive features when observed in X-rays, where both the most massive collapsed structure (clusters of galaxies) and the most energetic events in the life of galaxies (AGN and Quasars) reveal themselves unambiguously. The next generation of wide-area, sensitive X-ray surveys designed to map the hot and energetic Universe will be heralded by eROSITA (extended ROentgen Survey with an Imaging Telescope Array), the core instrument on the Russian-German Spektrum-Roentgen-Gamma (SRG) mission, successfully launched in July 2019. On December 13, after completion of its Calibration and Performance Verification phase, SRG /eROSITA has begun its four-years program dedicated to surveying the entire sky eight times in the energy range ~0.2-8 keV. The high sensitivity, large field of view, high spatial resolution and high survey efficiency of eROSITA is bound to revolutionize X-ray astronomy: within just the first year of operation it will discover more new celestial X-ray objects than have been catalogued from 1962 until today. I will present an overview of the instrument capabilities, the current status of the mission, the early science results and the expectations for the X-ray all-sky survey program and its planned followup programs.