September 16, 2024
You share your birthday with the light of distant galaxies that has been traveling for millions of years just to arrive here, now, alongside...
Mercury's Vivaldi Crater from BepiColombo
Birthday · September 16, 2024
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APOD published September 16, 2024. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
Why does this large crater on Mercury have two rings and a smooth floor? No one is sure. The unusual feature called Vivaldi Crater spans 215 kilometers and was imaged again in great detail by ESA's and JAXA's robotic BepiColombo spacecraft on a flyby earlier this month. A large circular feature on a rocky planet or moon is usually caused by either an impact by a small asteroid or a comet fragment, or a volcanic eruption. In the case of Vivaldi, it is possible that both occurred -- a heavy strike that caused a smooth internal lava flow. Double-ringed craters are rare, and the cause of the inner rings remains a topic of research. The speed-slowing gravity-assisted flyby of Mercury by BepiColombo was in preparation for the spacecraft entering orbit around the Solar System's innermost planet in 2026.