APOD: 2025 March 16 – Venus and the Triply Ultraviolet Sun

Good afternoon, Rallypoint, and welcome to this edition of Astronomy Picture of the Day for March 16, 2025.

The Solar Dynamics Observatory (SDO) was launched back in 2010 and has been on station since then studying our Sun. This SDO image from 2017 shows all three flavors of ultraviolet (UV) radiation: UV-A (wavelength of 315-400 nanometers), UV-B (wavelength of 280-315 nanometers), and UV-C (wavelength of 100-280 nanometers). Most of the UV-B and UV-C radiation is absorbed by Earth's atmosphere. Most of what reaches the ground is UV-A.

The black 'dot' is the shadow of Venus as it passed between the Earth and Sun when this SDO photo was taken. The next Venusian 'eclipse' won't happen again until 2117.