Trollheart

Well I’m afraid we can’t ignore the science like the Republicans, and we have to check out some of those tedious specs about the Sun. So here they are.

Diameter: Approx 800,000 KM* (109 times that of Earth)
Volume:** Approx 1,300,000 times that of Earth
Mass: Equivalent to 333,000 Earths
Gravity: 28 times that of Earth
Distance from Earth: 150,000,000 kms (1 AU***)
Star Type: G
Sidereal rotation period (at equator): Yeah, like we’re going to get into that kind of shit! Didn’t you see the logo above? As if.

* As I couldn’t be arsed constantly converting this to that, I’ve picked one measurement to go with and it’s kilometres, where I can use it. You want miles, I got one word for ya: Google.

** The size of stars makes many of the measurements used a little hard to understand for a non-brainiac like me (see? I couldn’t even spell brainiac without three attempts to do so!) and it makes it easier to use its relevance to Earth, so, rather like the annoying way they say on certain documentaries “100 feet, that’s two football fields” or whatever, here it’s a case of that much larger than Earth or in some cases so many Earths bigger. You’ll get the hang of it.

*** AU is the Astronomical Unit, which is basically, as above, 150 million km, or the distance from the Earth to the Sun. As we get out into space, things like kms don’t really cut it so you’ll find AUs being used a whole lot more, so get used to it.

Things I have learned about the Sun

Like I said at the start, this is a voyage of discovery as much for me as for you. Like most of my journals, I kind of know sod-all about the subject, or have a loose grasp of it, and supplement my knowledge through the time-honoured process of research. Or, to put it another, perhaps more accurate way, I look at the writing of people who know a hell of a lot more about me than the subject, steal it, rewrite it, and post it. Not literally obviously, and that’s somewhat satirical, but in the end, isn’t that what all research is? Looking to others to tell you what you want to know, and then imparting it to your readership?

As a result of this, I have already found out quite a lot about the Sun I did not know. And here is what I have found out.

The Sun is older than I thought. Not that I didn’t know how old it was, I just didn’t realise that it kind of straddles the middle age of stars, with the oldest being up to 14 billion years old (who’s paying for the candles on that cake, I wonder?) and the youngest counting their age in mere millions.

I did not know that our Sun is technically classed as a dwarf star. It is, a yellow one to be precise (which, given its actual colour is said to be white, confuses me, but then I’m easily confused). I also did not know that up to eighty percent of the stars in at least our galaxy are also dwarfs of various colours.

I thought that solar flares and solar prominences were the same thing. They’re not.

I had no idea that the Aurora Borealis (Northern Lights) and Australis (Southern Lights) are caused by eruptions from the Sun called CMEs, or Coronal Mass Ejections.

__________________
Trollheart: Signature-free since April 2018

Trollheart

Fun factoids

Many of these you will know, but I’m going to tell you anyway.

Like I noted in the introduction, in ancient times the Sun was both worshipped as a god and as a representation of a god, which is to say, the Egyptians for example revered the sun-god Ra, and the Sumerians believed the Sun was Utu, the god of justice and twin brother of the queen of Heaven, Inanna. The Greeks and Romans explained the movement of the Sun across the sky by imagining it was draw in a golden chariot by Helios, who had to rest at night, thus darkness fell. They also were under the mistaken impression that the Sun was a planet, which is why they named the seven days of the week after seven known planets at the time, including the Sun. (These appear to have been the only ones that could be seen with the naked eye - so Mercury, Venus, Mars, Jupiter, Saturn, the Moon and the Sun - oddly, they didn’t include Earth, whether they understood or believed it too was a planet I don’t know).

Norse legend didn’t have much about the Sun, but then, given how damn cold it is up there in Scandinavia, they probably didn’t see it often enough to assign it the importance of a god, though the Chinese believed there were originally ten Suns but they messed around too much in the sky and burned the people, so a hero shot nine of them down, leaving just the one. Weird, but I suppose no weirder than thinking the sun was driven across the sky in a chariot. I mean, who would insure such a daily trip? And whoever they were, I bet Helios lost his no-claims bonus when his son Phaeton snagged the keys and the whole thing went tits-up. But I mean, come on: these people (the Chinese) also explained a solar eclipse as the bite of a magical dragon or dog. Right. Sure they did.

Ah well we Irish weren’t much better. Sure we used to swear that the sun was a woman, honest! Even Christianity took the idea of using December 25 from a sun-worshipping crowd, as explained by the 12th century Syrian bishop Jacob Bar-Salibib (died 1191): "It was a custom of the Pagans to celebrate on the same 25 December the birthday of the Sun, at which they kindled lights in token of festivity. In these solemnities and revelries the Christians also took part. Accordingly when the doctors of the Church perceived that the Christians had a leaning to this festival, they took counsel and resolved that the true Nativity should be solemnised on that day."

Back in the real world, ultraviolet light from the sun is what causes sunburn if you don’t use the old Factor 500 or whatever, and of course as we all know by now it also causes skin cancer, though it has its good points too, being responsible for varying degrees of human skin pigmentation due to its being filtered through the Earth’s ozone layer at different latitudes. But back to bad stuff, and we all know that despite both U2 and Threshold (who?) writing songs called “Staring at the Sun”, this is bad advice, and can result in temporary or even permanent blindness. That’s just from looking at the sun with your eyes (though your natural defences make you blink and squeeze your eyes shut pretty quickly, so unless you’re really stupid, or want, for some reason, to damage your eyesight, the chances of that happening are relatively low) - try using binoculars or a telescope and say goodbye to those eyes. Just because it’s over 170 million kilometres away doesn’t mean it can’t sear your retinas after a few seconds, so don’t even risk it.

And you might think (though again you’d be an idiot if you did) that it might be safe to look at the Sun during an eclipse, when most of it is blocked by the Moon. But it isn’t. If you’ve ever participated in such an event, you should know that you need special protection even then to look directly at the sun, and you’re placing your eyesight at grave risk if you ignore the safety instructions and don’t take the recommended precautions. Why do you have to do this? Glad you asked.

Despite what we all think, the uncovered portion of the Sun left visible during the eclipse is still as bright as during a normal day, and not only that, but the human pupil opens more to compensate for the loss of light, about three times as wide, which actually allows up to ten times as much light into it as would normally be the case. Finally, you don’t even feel your retinal cells dying. There’s no pain, it just happens, and suddenly you have blind spots and trouble seeing. So basically, don’t take the risk. This even happens during a partial solar eclipse, so just watch it. Or preferably, don’t.



The thing about space exploration is that you really do end up getting bogged down in science-y talk and figures and jargon. The very first book I read to get information about the Sun, The Inner Solar System: The Sun, Mercury, Venus, Earth and Mars (An Explorer’s Guide to the Universe) by Erik Gregerson bombarded me with so many crazy concepts - electrons, photons, protons and neutrons all doing their thing, this to the power of that, measurements I had never even heard of before, the angle of the ecliptic (well that wasn’t there, but I’ve heard it before and thought I’d use it just to sound brainy. What is it? How the hell should I know?) and chemical symbols all over the place, that I became… what is that word? There’s a word for what happened to me when I read it (or rather, scanned down it, going a little glassy-eyed in the process) - oh yeah. Bored. I got bored.

See, as I said at the beginning, and as the reappearance of the logo above should remind you, although this is to be a voyage of discovery it ain’t a school trip, or an academic attempt to prove this or postulate that, or even a serious attempt to quantify the phenomena of the universe. Nah. This is, primarily, a sight-seeing tour, where I’ll be pointing out items of interest and doing what I can to talk about them without sending you all, and myself, to sleep.

So I am studiously (if that’s not a contradiction in terms, and if it is, then suck it) and deliberately ignoring the harder bits, the ones where these brainiacs go into deep detail and get all science tech and prove they could not only buy and sell me on their subject, but give me away as a free gift. They can do that, and more power to them (to the power of whatever). Me? I just like learning stuff, but not stuff that’s going to crowd out my brain and make it hurt. Therefore, if, as we pull away from the Sun you’re waving your arms and shouting but but but! You didn’t explain how this works and I want to know about that and I don’t understand the other, just sit down and get a grip, will you? Nobody cares, and if they do, there’s this wonderful thing called the internet where you can find out anything you want and go as deep as makes you happy, but the rest of us will be off enjoying ourselves.

All sounds very frivolous, doesn’t it? Good. While I will be ensuring we all learn the basics about things like planets, comets, galaxies, pulsars and asteroids shaped like dancing moose, I want to keep it interesting but also entertaining, light-hearted and easy to follow. So I guess you might call it The Universe for Dummies, though if you call me a dummy you may be asked to check that faulty airlock down on deck seven. Unless you’re into science in a heavy way, like Marie, maybe Frownland, a few others, or do it for a living, it’s usually been my experience that too much information can be a real pain and people lose interest very quick. So we’re doing the basics, and no more. You want to find out more, be my guest. The rest of us are just here to enjoy the trip.

So break out the space beer - which is, basically, just beer you drink in space. So, yeah, beer. So break out the beer and let’s visit the neighbours, as we leave the Sun behind and knock on the door of the guy who lives nearest the big yellow one.

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Trollheart: Signature-free since April 2018

Trollheart

II: (Sometimes) Hotter than Hell: Welcome to Mercury

Even the least informed among you will be aware that Mercury is the closest planet to the Sun, and therefore the hottest. Well not quite. I always thought this, but it seems that because Mercury has no atmosphere, and therefore no way to retain heat, despite its heat source being only 58 million km away, its surface temperature fluctuates wildly between day and night. In the day it can reach temperatures of up to 800 degrees Centigrade, whereas at night it plunges to -173 C. Anyone trying to list off the planets (come on, who would fail at such a task? Oh well, I remember someone on a quiz recently apparently forgetting the soil he stood on was part of a planet, and thinking it was Mercury, Venus, Mars….) will always know that Mercury comes first, so it’s always uppermost in people’s minds. It’s also the smallest of the planets as you might expect, a mere 0.05 times the size of Earth, with gravity at 0.3, which I guess means you could fly on Mercury, if you weren’t busy being fried to a crisp, that is.

Mercury is one of only two planets in our solar system devoid of moons, its nearest neighbour being the other. In some ways, Mercury displays some of the characteristics of our moon at least - pock-marked with craters, inactive, dead and without any atmosphere, although nobody to my knowledge has ever written a song called “By the Light of the Silvery Mercury” or suchlike. Just doesn’t have the same romanticism. Another reason why, perhaps, Mercury doesn’t figure all that much in human culture - certainly not as much as Mars, Saturn, Jupiter and Venus, for instance - is that it’s very damned hard to see. Because its orbit is within that of Earth, and due to its proximity to the Sun, it can usually only be seen after sunset on the western horizon and before sunrise on the eastern.

It’s a lot denser than Earth, by which I don’t mean it gets a lower SAT score: its core takes up about 55% of the planet, whereas ours only extends to 17%, and Mercury is one of the richest sources of iron in the solar system. Long narrow ridges extend for several hundred kilometres along its surface, as well as mare*-like plains and craters, similar to those on the moon. Like the moon, it also has highlands, mountains, valleys and escarpments. Some of the craters are hundreds of kilometres wide, though some are quite small. The largest is called Caloris Basin or Plantitia, and is 1,500 km wide.

Due to the contraction which occurred as Mercury cooled, the surface has been deformed into things like wrinkle ridges and lobate scarps (curved or scalloped cliffs), as well as compression folds known as rupes or cliffs. The many volcanoes on the planet (billions of years dormant now of course) are all of the shield variety, which means they’re almost flat to the ground, rather than the ones we’re familiar with, caldera and mountains. Perhaps strangely, given its proximity to the Sun, it’s theorised that ice may exist on Mercury. This is supported by the fact that the temperature at the poles, which never receive direct sunlight, is always at about -170 C, and cold traps have developed on the floors of deep craters at the poles. Messenger, a probe sent out in 2012, confirmed that there is enough water ice at the north pole of Mercury to “encase all of Washington DC in a block of ice two and a half miles deep”. The next probe to visit Mercury, scheduled to arrive in 2025, will explore this further.

* A Mare is a flat, basaltic plain created by volcanic eruptions, the word coming from the old Latin for sea, which is probably how they were once viewed in early times.

Ever asked yourself if this day would ever end? Well thank your lucky stars you aren’t on Mercury, where the day lasts 1,400 hours or approximately 58 Earth days! Try getting through that one without telling the boss where to shove his job! As for years, well this is quite weird, because it seems Mercury spins faster on its axis than it rotates around the sun - a trip which takes it 87 days - meaning that one Mercury year doesn’t even last two Mercury days! Imagine all the presents you’d be getting for birthdays! Then again, imagine how quickly you’d age if every year was only 87 instead of 365 days. Oh man! I’d be, what, well over two hundred years old! Bet I don’t look a day over a hundred though.

Because the planet’s tilt is almost zero, the least of any of the planets in our system, an observer on Mercury would see the sun rise almost two-thirds of the way over the horizon, then reverse and go back down and come back up, all in the same day! Hey darling, let’s go watch the sun rise, set and rise again, shall we? It’s so romantic! Oh but that’s not the best of it. Once every Mercurian year (every other Mercurian day, in other words) at certain points on the planet’s surface the sun goes overhead, reverses direction, comes back over again, reverses direction again and comes back over a third time. At this point, the Sun is basically stationery. No, that’s not right is it? That would mean our native star suddenly became a load of pens and paper clips and notepads. Stationary, that’s the one. Not moving. Stopped. Like the queue in the post office just when you have to catch that bus.

Kind of amazing to hear that a report issued in March 2020 suggested that life may at one time have existed on Mercury, although it’s unlikely to have been bronze-suited Mercurians saluting the huge god that seemed always to be watching over them, but rather tiny micro-orgasms, sorry organisms. Not expecting too much in the way of written history, then. Interesting that several cultures all linked the planet with their version of the messenger of the gods, the Babylonians naming it Nabu, the Greeks Hermes and the Romans of course Mercury, which was the one which stuck. This might be because (Trollheart Hypothesis # 340, all rights reserved) it is the planet closest to the sun, which was generally seen as the father or creator god, so this planet would be designated as its messenger. Maybe. Who knows?

Probes sent

Mariner 10

Launched: 1973
Reached Destination: 1974
Results: Mapped about 45% of the planet, confirmed its very weak atmosphere of helium, the existence of a magnetic field and also confirmed the highest deposits of iron found in any of the planets. Determined maximum and minimum temperatures on the surface of the planet.
Photographs taken: 2,800
Mission ended: 1975
Termination of probe: Deactivated remotely and believed yet to orbit the Sun

MESSENGER (MErcury Surface Space ENvironment GEochemistry and Ranging)
Note: Isn’t it weird how everything associated with Mercury turns out to have to do with messengers? Obviously, this one was planned, but still. I mean, let’s be honest, the acronym is about as forced as you can get. It could easily have been called the Monsignor, or I don’t know, the Massager?)
Launched: 2004
Reached Destination: 2008 (but flybys only; entered Mercury orbit 2011)
Results: Mapped 100% of surface, examined the atmosphere, made detailed study of the planet’s geology from orbit, studied its magnetic field, its surface, the poles and the core. Discovered the presence of water, also volcanoes. The revelation that there were carbon-containing organic compounds on the planet led to speculation that life might have existed there once.
Photographs taken: 100,000
Mission ended: 2015
Termination of probe: Crashed into Mercury

Future probes

BepiColumbo

Launched: 2018
To reach Mercury: 2025

Mercury-P (Меркурий-П)

Launch date: 2031 (planned)
As you might have gathered from the characters, this is being launched, or at least its launch is proposed, by the Russian Space Agency, and if successful will be the first probe to actually land on the surface of Mercury.

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Trollheart: Signature-free since April 2018