This image is an artistic rendering of the global distribution of ionized sodium (Na) and helium (He) near the planet Mercury. Sodium exhibits distinct maxima near the magnetic cusps, where neutral atoms are likely liberated from the surface by solar wind ion bombardment. Helium is much more uniformly distributed, such as would be expected if the dominant source process were evaporation from a helium-saturated surface.

Date Presented: September 29, 2011, at a NASA Press Briefing
Instrument: The Fast Imaging Plasma Spectrometer (FIPS)

These images are from MESSENGER, a NASA Discovery mission to conduct the first orbital study of the innermost planet, Mercury. For information regarding the use of images, see the MESSENGER image use policy.