Ad Astra: Trollheart's Guide to the Galaxy (And Beyond)

[Trollheart]

As a child, another of my nerdish interests was in space. Not quite so much astronomy - I tried that, but never really got into it in any sort of proper way, the same as I dabbled (using the word very generously) in photography and playing the keyboards - but space itself. This isn’t terribly surprising when you consider a few factors. One, I was a kid. What kid isn’t attracted by space, the stars, travel through the galaxy, aliens etc? Two, I was already into science fiction, so space was almost by default the backdrop for most of what I was reading, and three, space is interesting. It’s interesting on the surface because there’s so much of it and we have explored virtually none of it. The idea of strange and distant stars, planets which might support life (and life vastly different to our own, most likely), to say nothing of the likes of quasars, pulsars and of course black holes, is always attractive, if nothing else, due to the mystery of such phenomena.

Down with Science!

Not really. I'm not advocating the new Republican way, championed (if that's the right word) by an orange hobgoblin who never learned the first lesson of sportsmanship and how to lose gracefully. I'm not ignoring, challenging or denying science in any way. But hell, for a lot of us science is, what's the word, oh yeah, boring.

In my initial search for books to support my research into this journal, I came across a lot of writing on particle physics, quantum theory, mathematics of the cosmos and so on, and I left them where I found them. While there has to be a certain amount of science in any exploration, even written, of our universe, I don’t want to get bogged down in dry scientific details, and I don’t have that sort of brain anyway. Much of what I would be reading would be incomprehensible to me. Marie Monday may be at sea when it comes to computer technology, but she can run (Saturn’s) rings around me - indeed, most of us - when it comes to the likes of string theory and quantum mechanics, and good for her. But I hated maths as a child and young adult and I never quite got it, and the whole subject bores me. And while I may have no problem boring my audience with my many and varied journals, I’ll be damned if I’m going to bore myself!

So what I intend to do here (how very original I hear you sneer) is to take you on a sort of travelogue of the galaxy, and, as the title promises, most likely beyond that too. I’m going to begin by investigating the planets that surround our sun and make up the solar system in which we live, and then range out further afield, going from star to star as if we’re in a cosmic cruise liner (no, NOT a spaceship of the mind! Keep your allegations of plagiarism to yourself, Neal DeGrasse Tyson!) taking a trip through the wonder of space (no, you can sod off too, Brian Cox! Just because you’re a professor science space guy doesn’t mean you have a monopoly on talking about the universe!) and seeing what it has to offer.

I have the vaguest idea myself of the cosmos. I know all the planets of course - though probably, almost definitely not as well as I think I do, and we’ll find that out here - and a few facts about stars, black holes, quasars, the usual stuff. I’ve heard of the Gates of Creation, the Horsehead Nebula, the Large and the Small Magellanic Clouds, wormholes, gamma ray bursts and binary star systems. I know what they believe the giant red spot on Jupiter is and I know that Venus is almost the same size as Earth. I know the atmosphere on Titan, Jupiter’s largest moon, is made of methane, and that there are volcanoes on Neptune several miles high. But all of these facts, or even factoids, in most cases make up the sum total of my knowledge of each of these planets, while of course I know there is so much more to learn about them. And that’s just the planets. I know Albedaran is a Red Giant, as is Betelgeuse. I know Proxima Centauri is our nearest star, that the Andromeda Galaxy is our closest neighbour, and beyond that I know the names of some stars - Vega, Altair, Cassiopeia, Sirius, Procyon and so on - but that’s all I do know about them.

So this will be a journey of exploration and discovery for me as much as for anyone who reads this. Together we’ll board the cruiser to the stars and head out into the vast reaches of the Milky Way, seeing all the sights we can and learning about the stars and maybe planets, and other stellar phenomena and cosmic points of interest in our own galaxy, before ranging further afield, and travelling to the very boundaries of the universe. I’d advise packing a lunch - replicator food does not come recommended. And make sure your phone is charged: I don’t want any of you draining the precious resources of our ship.

While the intention is to give you some information here, to educate and explain, we’ll be leaving the nuts and bolts and the textbooks to others more qualified than I. Hey, even if you don’t learn anything (though you surely will) there’s still going to be some amazing sights to be seen on our journey, and all you have to do is look out one of the windows. What? Viewscreens? What do you think this is: the starship Enterprise? You have any idea how hard it was to finance this trip? Viewscreens? You’re lucky we have windows!

The name of that ship? Let’s call it - hmm. Let’s call it the Darwin. The man who would become the very father of evolution theory travelled to distant lands in search of the origins of life, so we can now emulate his journey on a cosmic scale, and therefore it only seems right that our interstellar cruise liner should bear his name.


Darwin. The man, not the ship. But then, you knew that. You, uh, did know that….?

So make sure you have your boarding passes, take your spacesick pills and - no you don’t need to put your helmet on: this is a pressurised environment. Where do you think you are? The twentieth century? - prepare for the trip of a lifetime.

Oh, there are no refunds. Just thought I’d mention that.

Right then, in the immortal words of Captain Jean-Luc Picard: let’s see what’s out there!

[Trollheart]

Research Sources

Before we get underway, and as the flight engineer goes through his pre-flight checks and the quartermaster makes sure all is loaded aboard ship that should be, here’s a list of the books I will be using for research, in addition to Wiki and any other sources I can track down, such as TV series like The Planets and Cosmos, Wonders of the Solar System and anything else I can rip off.

Cosmic Chronicles: A User’s Guide to the Universe by Fred Watson

Universe: A Definitive Guide by Martin Rees

We Have No Idea: A Guide to the Unknown by Jorge Cham and Daniel Whiteson

Your Ticket to Exploring the Universe: A Guide to the Cosmos by Kimberly K. Arcand, Megan Watzke and Mario Livio

The Milky Way and Beyond: Stars, Nebulae and Other Galaxies - An Explorer’s Guide to the Universe by Erik Gregersen

The Outer Solar System: Jupiter, Saturn, Neptune, Uranus and the Dwarf Planets - An Explorer’s Guide to the Universe by Erik Gregersen

The Inner Solar System: The Sun, Mercury, Venus, Earth and Mars - An Explorer’s Guide to the Universe by Erik Gregersen

Guide to the Universe: Stars and Galaxies by Lauren V. Jones

The Universe in Your Hand: A Journey Through Space, Time and Beyond by Christophe Galfard

A Journey Through the Universe by Jayant Narlikar

Guide to the Universe: Asteroids, Comets and Dwarf Planets by Andrew S. Rivkin

A User’s Guide to the Universe: Surviving the Perils of Black Holes, Time Paradoxes and Quantum Uncertainty by Dave Goldberg and Jeff Blomqvist

The Universe: Explained, Condensed and Exploded by Richard Osborne

Life in the Universe: A Beginner’s Guide by Lewis Dartnell

Life in the Universe by Dirk Schulz-Makuch and Louis N. Irwin

Edge of Infinity: Supermassive Black Holes in the Universe by Melia F

The Living Cosmos: Our Search for Life in the Universe by Chris Impey

Don’t Know Much About the Universe by Kenneth C. Davis

The Universe in a Nutshell by Stephen Hawking

Philip's Atlas to the Universe: Intro to Astronomy by Patrick Moore

Britannica Science Illustrated Library Universe

Galaxies in the Universe: An Introduction by L.S. Spark and J.S. Gallagher

Burnham’s Celestial Handbook: An Observer’s Guide to the Universe Beyond the Solar System by Robert Burnham Jr.

Origins: How the Planets, Stars, Galaxies and Universe Began by Stephen Eales

[Mindfulness]

Subbed to this thread too!

[Trollheart]

So, it makes sense to start off with the planets in our solar system, right?
Well, not quite…


Chapter I: Dropping in on the neighbours: A stroll through our solar system

I: Sunshine on my face: our local star

Yeah, the most important part of our own solar system is of course that which gives it is name, Sol, or more commonly, the Sun, so that's where the Darwin is bound on the first leg of our local journey. Make sure you have your shades on: it's damned bright out there! Insurance? Umm.. oh! Look!

While a sun is in fact any star, and every single other star is named (some of which I’ve noted above) ours really never had a name other than “the Sun”, though ancient astronomers did use their own name for the sun, that being Sol, and so sometimes, to distinguish it from other stars or suns, it is referred to as Sol. But really, it’s quite rare that this happens and so throughout this journal I will be calling it the Sun. And it’s our sun, our celestial father who provides us warmth and light and, well, life. No wonder the ancients used to worship it, both as an actual object and as a god, or personification of one. After all, without the sun we’re all dead. Once that glowing orb in the sky that allows you to go bicycling or sitting in the park, or shines hard in upon you at your desk or as you trudge across desert sands, once it goes out, it’s all over people. The Sun nourishes all the planets, keeps them together by the force of its powerful gravitational pull, and regulates their temperature and therefore their weather.

For a very long time, it was firmly believed that the Sun went around the Earth, not the other way around. This was, mostly, because people could not conceive of Earth as being other than the centre of the universe (as was known at the time, which was the few stars visible to the naked eye, and probably not even recognised as such). God, or the gods, had created the Earth, so it stood to reason that it was the most important object in the sky. Well into the sixteenth century, the Christian Church preached that Earth was the centre of the universe (and flat) and if you disagreed, it was off to the Inquisition with you, for a one-time only, all-expenses-paid single ticket to hell and damnation. No, the Church did not take kindly to having its laws questioned, and even Galileo Galilei, known to history as Galileo, was persecuted and tortured by them for daring to suggest otherwise.


(Well, Galileo did, at least, the Italian version. And he was not wrong... Say anything at all, or even look like you were going to say something that contradicted or even questioned Church dogma, and you could expect a summons. And I don't mean a subpoena either)

But as science began to throw back the shadows of superstition and ignorance, and humanity emerged out of the darkness, new lines of thinking began and, more importantly, advances in technology and science meant that certain facts, held to be unalterable by the Church, such as Earth’s position in the cosmos, were proven completely baseless and untrue, and the reality was widely disseminated, along with actual proof. In 1992, more than three hundred years after he had been branded a heretic and condemned to house arrest after he recanted his “blasphemous” theory that the Earth revolved around the Sun, Galileo received a posthumous apology from the Church, when Pope John Paul II basically shrugged and said “sorry dude, we got it wrong. No hard feelings?” Well, I guess it was something, even if it was three centuries too late.

We now know the Sun to be the centre of our solar system, with eight (originally nine, until poor Pluto was demoted to the status of dwarf planet and removed from the solar system party invitations mailshot) planets orbiting it at different distances, one of which is of course ours. Contrary to popular belief for millennia, and to literary descriptions still used, the Sun neither rises nor sets, this effect being produced as the planet moves around the disc of the Sun, turning its face from the star (of course it’s never fully turned from the Sun, which is why when it’s day in the northern hemisphere, for example, it’s night in the southern). Our Sun is a G-type star, which kind of means it’s nothing special. It’s not a Red or Blue Giant, nor is it a White or Red Dwarf. It’s not a binary or trinary star and it’s not a pulsar, luckily for us. It’s the kind of star that might get mugged for its lunch money walking down the street by the likes of Arcturus or Rigel, or maybe that old bully Betelgeuse, and it would never get to take the pretty girl to the prom. It’s ordinary, in other words.

But it’s our Sun, and while Red Giant might sound like a cool name for a star, trust me, you would not want to live on a planet orbiting one. In reality, you probably couldn’t, as we’ll see later. The Sun is basically a massive hydrogen bomb, with about three-quarters of its mass made up of that element, the rest mostly helium, and 600 million tonnes of hydrogen get converted by the process known as nuclear fusion into helium every second. The Sun is a sort of middle-aged star, four and a half billion years old, but it’s a grizzled old man compared to the sprightly Red Giant Betelgeuse, which has only been around for a piddling ten million, or the blue supergiant Rigel, a mere whippersnapper at seven million (estimated). The oldest stars known to exist go back thirteen to fourteen billion years since their formation. And you thought you felt old on your last birthday!

Eventually though, the Sun will use up all its hydrogen - nothing lasts forever - and transform into a Red Giant, in the process taking out our nearest neighbours, Mercury and Venus, and wiping all life from our own planet. But no need to book a spot on Branson’s Virgin Galactic just yet, you have time. This is estimated to occur in around five billion years, so lots of time put the kettle on and have a nice cuppa.

Under the hood: everything under the Sun

The Sun, like most stars, is constructed of several layers, at which we will now take a quick look. Don’t get too close: the surface of the Sun reaches temperatures of about 5,500 degrees Centigrade (nearly 10,000 Fahrenheit) - talk about sunburn! It’s actually so hot that no liquid or solid matter can survive there, and so the Sun is basically a giant ball of superheated gas. Want to land on its surface? Tough. Even if you could somehow construct a craft that would resist such matter-melting temperatures, there’s nothing there to land on. You might as well attempt to plant your flag of stupidity on the surface of Jupiter - which, again, has none. In fact, quite a few of our planets are gas giants, but again we’ll come to them in due course.

Spoiler for Cool picture but too big, as it offsets the text. Click to see.:

Core

This is, as you might expect, the very centre of the Sun, making up about a quarter of its surface, and is where those chemical reactions I spoke of earlier takes place. Hydrogen is fused to helium and produces energy. If you thought the surface of the Sun was hot (it is) then get this: in the core, temperatures regularly reach up to fifteen million degrees (I’m not going to translate that to Fahrenheit because a) what’s a few million degrees between friends and b) my thermometers keep vapourising) and the pressure is immense (there are some science-y measurements but they don’t mean anything to me and probably won’t mean anything to you, so let’s just say if you feel pressure about your impending nuptials or that promotion you’re hoping for, or your upcoming gig, try doing it at the core of the Sun and see how you feel!) as hot, dense plasma is fused to produce the energy and heat the Sun gives off, and sent via several layer to the surface, first by radiation and then, once it’s got through the denser layers, by convection.

Radiative Zone

Sounds like something out of a Superman comic, doesn’t it? But no, this is actually the next layer of the Sun, where the energy released in the core is transformed by photonic radiation and sent on its journey towards the surface. Because the matter is so dense here, it can take over 170,000 years for gamma rays to get to the surface of the Sun, which is good news for us, as gamma rays are very dangerous and we don’t really want to see the Sun spewing them out during our lifetime.

Tachocline

This is a buffer zone between the Radiative and the Convection Zone

Convection Zone

See? The Convection Zone (not to be confused with the Convention Zone, a floating space platform for those who constantly go to meets and symposia) is where the energy from the core of the Sun is pushed to the surface by convection (by the circulation of currents within the star) rather than radiation (via electromagnetic photons) as the solar plasma from the core loses density and heat, and currents develop to carry the energy to the surface.

Photosphere

The part of the Sun we’re all most familiar with, the basic surface, the layer below which the Sun becomes opaque to visible light, and we see sunlight. This is the effect of photons escaping through this layer and the transparent atmosphere below it, becoming solar radiation, sunlight.

Atmosphere

We’re used to hearing this word, and it describes the ratio of gases that surround a planet, making it either breathable or not. As mentioned earlier, Titan, Saturn’s largest moon, has an atmosphere composed primarily of methane, which is poisonous to humans, whereas Earth’s atmosphere is mostly Oxygen and Nitrogen, which is not. But the Sun’s atmosphere refers more to the corona surrounding the star, which is made up of four separate elements.

The Chromosphere, transition region and corona are all hotter than the surface of the Sun. The transition region stands between the Chromosphere and the corona, the latter being the kind of halo we see around the Sun, and the thing we draw when kids as either wavy lines or spikes coming off the disc. It’s also the sort of shimmery halo you see when there’s a solar eclipse. It is in constant motion, moving at a rate of about 400 KM/second, called the solar wind. The final layer, the uppermost, is the heliosphere, and is filled with solar wind plasma.

Solar phenomena

We’ve all heard of the weird things stars - well, our Sun anyway - tend to do, but a quick checklist here.

We have solar flares, which are sudden flashes of brightness on the surface of the Sun, accompanied by ejection of coronal matter and which emit powerful radio waves, which, if the flare comes close to Earth, can penetrate the atmosphere and disrupt communications such as radio and television, and possibly internet too. They can also appear as bright auroras in the ionosphere.

Then there are sunspots. These are not, as you might possibly think, our native star having a bad case of acne, nor indeed places where holidaymakers go to escape the rain, but are in fact areas on the surface of the Sun - ranging in size from a tiny 16 km across to a maximum 160,000 - where the temperature has dropped slightly. They are indications of intense magnetic activity, and often give rise to the aforementioned solar flares, as well as coronal mass ejections. They travel across the surface at speeds of about a few hundred metres per second, and in the case of larger ones, can be seen with the naked eye. If, that is, you decide like an idiot to look directly at the Sun, which is not recommended.

Coronal mass ejections? Oh yeah I mentioned them didn’t I? Well they’re basically plasma thrown off the surface of the Sun, accompanied by magnetic field, and often, as I said already, associated with or follow solar flares. They, too, occur around sunspot areas and they can also arise during solar prominences, of which more in a mo. They get released into the solar wind, and at maximum solar activity there can be anything up to three a day, whereas on the other end of the scale, at minimum solar activity, you might be lucky to see one every five days. If a CME hits Earth atmosphere it can kick up a geomagnetic storm, like the big one in 1989, which took out Quebec’s power grid for nine hours, plunging the city into darkness and leaving the area without electricity. CMEs can also carry SEP (Solar Energetic Particles) which are responsible for both the Northern and Southern Lights, at the North and South Pole respectively.

The last one I want to look at here (there are others, but hell, they’re mostly boring, and we don’t do boring) are solar prominences, which I rather foolishly believed until a few hours ago to be the same as solar flares. They’re not. Solar prominences remain anchored to the surface of the Sun, creating kind of loops that go from the photosphere to the corona, and while they can break apart and become CMEs, usually this tends not to happen. They can last for weeks or even months and are huge - the largest on record almost the diameter of the Sun itself, about 800,000 kilometres. A prominence viewed against the Sun instead of against space is called a solar filament.

[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]

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.

[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.

[Mindfulness]

[Trollheart]

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 shit 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!

[Plankton]

My very first 3D project was our solar system in real world units. This was 1991 or so and I had access to our company's CAD system 24-7, so I'd go in at night and play around. I learned quite a bit about the distances and sizes of our planets, as well as teaching myself the 3D world of AutoCAD and it's AME extension (which I got from a local community college via BBS). In the 3D model, if you zoomed in you could zoom all the way to my office and then if you zoomed in to the bathroom next to it you'd see a fly on the toilet, and if you zoomed in even further, you'd see a naked woman in the fly's eye. I only detailed a few things in the surrounding area and just the state outline, but it set the stage for a lifetime of building worlds in digital formats. Fun stuff.

Just a note, it was hard to tell what you were referring to in that last post. Maybe a bolded title would help the reader a bit.