It’s time for some boring figures. Sigh. Let’s get on with it then.
Distance from Sun: 70,000,000 Km - 49,000,000 km (Because Mercury’s orbit is so eccentric, two figures have to be used, one for when it’s closest to the Sun - Aphelion - and one for when it’s furthest away - Perihelion)
Distance from Earth: (approx) 85,000,000 kms
Diameter: 4,880 km
Density: 5.427 g/cm
Surface gravity: 0.38g
Satellites: None
Atmosphere: None, other than a very tenuous exosphere containing mostly helium
Length of day: 88 Earth days
Length of year: 58 Earth days
Axial tilt: 0.034 degrees
Mass: 0.055 Earths
Volume: 0.056 Earths
Surface Temperature Range: 430 to -180 degrees Centigrade
Weather: None
That Mercury could be cold. I mean, who did? And SO cold!
That there was ice, or even water, on the planet.
That it had virtually no atmosphere
That the sun can rise, set and rise in the same day!
That one Mercurian year - two Mercurian days
That Mercury moved within the orbit of Earth
That there’s a possibility the planet could have at one time sustained life, however basic
Look, let’s just say I knew sh
it about Mercury, and now I know a lot more. And I hope you do too.
Interesting factoids
Why, do you think, the planet was named after the Roman messenger of the gods? Well, I gave one possible reason in the text, but it’s also possible that the fact that the planet moves so fast, in relation to other planets, across the sky, is connected to the supposed fleetness of Hermes/Mercury, and even the Assyrians, some of the most ancient of the old races (sorry Cthulhu!) named it “the jumping planet”. Asian mythology calls it, oddly, the water star, while Hindu belief had it linked to the god Budha, who was believed to preside over the day known as Wednesday - possibly why the French word for that day is Mercredi? Odin was certainly linked with both the planet and the day, actually giving us our modern denomination for it - Woden’s Day (Odin was often called Woden) or Wednesday.
The Hubble Space Telescope, one of the most powerful and certainly most famous, and longest-serving, having been sent into orbit in 1990, is prevented from observing Mercury due to its proximity to the Sun. Just like I noted in the article on the Sun dealing with the dangers of blindness when looking into the sun with optical instruments, it would be catastrophic for anyone to view the tiny planet through the Hubble as the Sun would be too close.
Mercury is unique in the solar system in its rotation, as it spins three times on its axis for every two times it orbits the Sun. This, apparently, is referred to as a 3:2 spin-orbit resonance. Of course it is.
Although without question, the planet most championed by the writers of science fiction has traditionally been Mars (leading some people to refer, incorrectly, to all invading aliens as Martians, no matter their actual point of origin) Mercury has seen its fair share of tribute in print too. I remember reading Asimov’s
Lucky Starr books, one of which was called
The Big Sun of Mercury, and it comes up in other of his stories, as well as works by C.S. Lewis, Kurt Vonnegut and Ben Bova, among others. Most notably, Arthur C. Clarke sets his
Rendezvous with Rama there, and Mercury is also the backdrop for books by Larry Niven, Kim Stanley Robinson, Stephen Baxter and David Brin. It also shows up in
Star Trek Voyager, Futurama and
Sailor Moon, to name but a few.
Oh, and you’ll be completely unsurprised, I should imagine, to hear that the first telescopic observations of Mercury were made by (anyone?) - yes, the Church’s Public Enemy Number One, Galileo.
So that’s as far as we’re going to explore Mercury. Anyone else finding it very hot in here? I think I need a drink. I’ll be down in the bar if anyone wants me. Oh well surely you can guess where we’re headed next? If not, just look out one of the windows. No, I told you we couldn’t get funding for viewscreens, why don’t you listen? Of course you won’t fall out: they don’t actually open! I mean, what kind of idiot opens a window on a spaceship? And why? To breathe in lungfuls of cool, fresh vacuum? We’re in space, dummy, or did you forget? You want fresh air, head down to the arboretum. No, I know it’s one skinny scraggly tree and hardly deserves the name, but it’s better than nothing.
Or better yet, come with me down to the bar. I think it may be your round. No, no. I’m sure it is.
No, don’t worry: they’ll call us when we reach our next destination.
What do you mean, no funds for a comms system?
Damn it. Right, well, someone can come down and tell us.
Come on, come on: all this talking has made me thirsty!