21st-century astronomical events

The 21st century has witnessed a number of significant astronomical events and discoveries that have expanded our understanding of the universe. Here are some notable examples: 1. **Gravitational Waves (2015)**: The LIGO (Laser Interferometer Gravitational-Wave Observatory) made history by detecting gravitational waves generated by the merger of two black holes. This groundbreaking discovery confirmed a major prediction of Einstein's general theory of relativity and opened a new way of observing the universe.