https://science.nasa.gov/mercurys-sodium-tail

What is that fuzzy streak extending from Mercury? Long exposures of our Solar System’s innermost planet may
reveal something unexpected: a tail. Mercury’s thin atmosphere contains small amounts of sodium that glow
when excited by light from the Sun. Sunlight also liberates these molecules from Mercury’s surface and pushes
them away. The yellow glow from sodium, in particular, is relatively bright. Pictured, Mercury and its sodium
tail are visible in a deep image taken in late May from Italy through a filter that primarily transmits yellow light
emitted by sodium. First predicted in the 1980s, Mercury’s tail was first discovered in 2001. Many tail details
were revealed in multiple observations by NASA’s robotic MESSENGER spacecraft that orbited Mercury
between 2011 and 2015. Tails are usually associated with comets. The tails of Comet NEOWISE are
currently visible with the unaided eye in the morning sky.

Image Credit & Copyright: Andrea Alessandrini

> Mercury’s thin atmosphere contains small amounts of sodium that glow when excited by light from the Sun. Sunlight also liberates these molecules from Mercury’s surface and pushes them away.

Yep.

I’m still waiting for a photograph of Earth’s tail.

mollwollfumble said:

> Mercury’s thin atmosphere contains small amounts of sodium that glow when excited by light from the Sun. Sunlight also liberates these molecules from Mercury’s surface and pushes them away.

Yep.

I’m still waiting for a photograph of Earth’s tail.

doubt you’ll get that with a flat disc…

Why has the sun not blasted all of the sodium and atmosphere from Mercury?

It has nearly cleaned out Mars, and that is much further away.
Is there a continuous supply of sodium from the surface?

Very nice.