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See that bright, glowing object with a tail? That's not a comet. That's the planet Mercury.

The reason it has a tail is because micrometeoroids bombard the planet surface and knock tiny pieces of it into space. Those pieces contain mineral-building atoms like sodium—which, when hit by sunlight, glow. So what you're seeing is a thin, glowing trail of pieces of Mercury.

Excuse my uneducated question but does that mean mercury getting smaller with time? Or does it gain mass from meteorites while losing some from itself?