Yes, apparently the planet Mercury has some affinities with comets since it has a tail that shines with a faint yellow-orange light trailing millions of kilometers in the wake of the planet.
According to astronomers, since Mercury is well inside our Solar System, less than half the distance from the Sun to Earth (about 58 million kilometers), solar radiation constantly bathes this small planet, which is furthermore constantly shaken by the solar wind .
Like the wind that propels sailboats, solar radiation exerts pressure capable of degrading the planet's tenuous atmosphere. And it is this radiation pressure that will act on the gases in Mercury's atmosphere, giving the latter the appearance of a comet with a tail .
Mercury, the planet that looks like a comet
Mercury has virtually no atmosphere, because its very low mass (5.5% of the mass of the Earth) and its weak magnetic field (1% of that of the Earth) do not allow it to benefit from 'a gravity comparable to that of our planet.
However, Mercury has a thin exosphere little protected against solar radiation and solar wind, all the same gravitationally linked to the planet. It is mainly made up of atoms of oxygen, sodium, hydrogen, helium and potassium.
As you know, the ice that makes up the interior of comets begins to sublimate when these objects get closer to the Sun. Dust will then escape from the body of the comet, then will be propelled by the pressure of solar radiation in a long tail while the magnetic effect of the solar wind will shape the gas which also escapes from the comets.
It is therefore the proximity of comets to the Sun and not their movement that produces their tails. And apparently it's the same scenario for Mercury.
A tail that can tell us a lot about Mercury
Mercury's tail is mostly made of sodium atoms that glow when ionized by ultraviolet radiation from the Sun. This gives Mercury the appearance of a comet with a tail dripping nearly 3.5 million kilometers in its wake.
In particular, Mercury's tail provides the opportunity to learn more about the seasonal variations of its exosphere and how it is affected by events such as solar flares and coronal mass ejections. Researchers also believe it could tell us a lot about the habitability of this small planet.
Nov 10, 2020:
That's not a comet but the tail of our inner planet Mercury ”seen“ from my backyard. This stacked image was exposed through a custom-made Sodium filter. The horizon is from the first exposure. #mercury #spica #yellow #sodium #sodiumtail #spica #astronomy #science pic.twitter.com/vjpK3RAkeA
– Dr. Sebastian Voltmer (@SeVoSpace) November 15, 2020