Need a New Role Model? Meet Mercury!

What’s your favourite planet? Saturn? Jupiter? Earth?

It’s probably not Mercury, so here are 3 reasons that it should be your favourite planet!
mercury-transparent

Mercury flaunts his natural face

A poreless face has been all the rage, but there’s nothing about Mercury’s surface that says smooth.

Mercury has the most cratered surface out of all the main planets. Despite how rich the surface is, it is still the least observed terrestrial planet. The first spacecraft to visit Mercury was the 1975 Mariner 10 flyby, and the only spacecraft since then to visit Mercury was MESSENGER.

This little planet is covered with craters, impact basins, mountains, plains, valleys, dorsa, and even volcanoes!

The_Mighty_Caloris_(PIA19213)
The Mighty Caloris! Credit: NASA/MESSENGER

Evidence suggests a lot of the features such as craters and impact basins were formed over 3.8 billion years ago, when Mercury (and the whole solar system) was young. Mercury is quite an inactive planet, so any geological features must have formed long ago.

Caloris Planitia is one of my top Mercurian features, as it has a bit of everything and shows that there was once volcanic activity. It is one incredibly large impact basin (1,550 km wide), which appears to have been smoothed out by lava.

Whilst the actual end of the basin is still up for debate, a large portion of it is surrounded by mountains! These are estimated to be small peaks, only about 2km high on average.

Mercury doesn’t care about his stretch marks

1280px-Spider_crater_on_planet_mercury
Pantheon Fossae and Apollodorus. Credit: NASA

One of the coolest features of Mercury is the spidery troughs around the planet, scientifically known as extensional faults. On Earth, these are caused by the stretching of the crust, similar to how stretch marks on skin form!

The most intriguing case of extensional faults lies within Caloris Planitia, naturally. In the image above is Pantheon Fossae, the name given to the spidery faults. Next to the troughs is the rather distinct crater Apollodorus. The cause of Pantheon Fossae is still unknown.

Mercury doesn’t conform to the orbital beauty standard!

MercuryPrecession

Another standard Mercury doesn’t conform to is the Newtonian one. Literally.

Planets that have eccentric orbits (practically every planet) will have a perihelion (closest approach) and aphelion (furthest approach).

The position of both perihelion and aphelion may change, mostly due to the gravitational effect from other larger planets, but otherwise should naturally be fixed in position…

…according to Newtonian mechanics.

In the real universe, and especially in Mercury’s case, this simply wasn’t true. The observed precession (shift in perihelion) was quite different to the predicted shift, a problem first noted by Le Verrier in 1859.

One of the first explanations was that there was another planet, named Vulcan, which was causing this extra shift. This planet should have been between the Sun and Mercury, yet no body could actually find Vulcan. Mercury was just that much of a strong independent planet.

Using Einstein’s General Relativity, however, the predicted precession just about matched the observed precession. In fact, Mercury’s un-Newtonian precession has been noted as an extremely well-known piece of evidence for General Relativity. Yippee, thanks Einstein! I’d like to see the Electric Universe believers top that!

Has Mercury won your heart?

Tell me with a comment. If not, tell me which planet is your favourite, it doesn’t have to be the main 8. It doesn’t even need to be in the Solar System!

Until next week!

4 comments

    • I’m glad that it made you happy! We’ve also got BepiColumbo being launched soon, which will be our 3rd spacecraft to visit Mercury! I’m rather excited for that!

      Like

  1. Venus is still my favorite, but I’ve come to have a lot of respect for Mercury. The fact that there’s water there was a real shocker. It’s not liquid water, obviously, but still that came as such a big surprise.

    Liked by 1 person

  2. Such a sassy bit of space rock Mercury is. I love it! You’ve convinced me. Venus is too gassy for me. I’m going with the sassy space rock–Mercury.

    Liked by 1 person

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