This animation shows the dark disk of Mercury against the backdrop of the Sun during a transit on May 7, 2003. The images used to make this animation come from the MDI (Michelson Doppler Imager) instrument on the SOHO (Solar and Heliospheric Observatory) satellite. SOHO is a joint project of NASA and ESA. The MDI images portray light with a wavelength around 6768 Ångstroms.
Image courtesy SOHO (ESA & NASA).