Jupiter is the largest planet in our solar system, by a huge margin — it’s 317 times more massive than Earth, and is eleven times wider. Everything about it is huge beyond comprehension, from a giant storm capable of swallowing Earth that has raged since at least the time Cassini spotted it in 1665, to radiation belts so intense they would be instantly lethal to anyone passing through them, to a huge constellation of moons including four that are in the solar system’s top six in size, to a gravity well so deep it’s been essential to every planetary mission sent into the outer solar system. It has held a high place in human mythology, with many cultures placing it in a supreme position — to the Greeks it was Zeus, to the Romans it was Jupiter, to the Babylonians it was Marduk, to the Aztecs it was Tezcatlipoca, and to the Egyptians, it was “Horus-who-bounds-the-two-lands” (one of three aspects of Horus represented by planets). And so you’d expect it to eventually show up on Doctor Who — which, of course, it eventually did.
The Android Invasion
The first time Jupiter became significant on the series was sort of tangential; the British astronaut Guy Crayford had been sent on a mission to the fifth planet, the first manned mission to that destination, and then contact was lost. The Doctor and Sarah Jane discovered him living in a replica of an English village populated by realistic androids built by a race called the Kraals. Crayford believes he was trapped in Jupiter orbit when his ship exploded, only to be rescued and put back together by the Kraals, but in fact they had only captured him and concocted the rescue story to win his trust. Their real goal is to invade Earth, using android duplicates to establish a beachhead before unleashing a virus that would destroy all life and then burn out, leaving the planet fit for Kraals. It’s not entirely clear where the Kraal home world is, nor whether Crayford actually made it to Jupiter, but the story is a lot of fun anyway.
Revenge of the Cybermen
A season earlier, though, the Jupiter system was much more clearly the setting. Before the Nerva Ark was established to house Earth’s elite during a period of intense solar activity, Nerva was a beacon orbiting Jupiter near a newly discovered moon astronomers have named Neo-Phobus, helping guide space liners around the poorly charted object. (Presumably the beacon is at one of the moon’s Lagrange points.) Astronomers believe the object to be a newly captured asteroid — but what they don’t know is that it’s inhabited, and the last fragment of a larger planet that was destroyed by the Cybermen. It is all that remains of Voga, the legendary planet of gold. Cybermen, you see, are vulnerable to gold. Once humans discovered this weakness during the Cyberwars, they invented a weapon called the Glitter Gun and quickly beat them back. The biggest source of the gold was Voga, and the Cybermen destroyed it in retaliation. The Vogans have survived and try to stay quiet lest the Cybermen rediscover them, although some of them chafe at this enforced isolation, and have made contact with a geologist working on Nerva — who has also made contact with a surviving group of Cybermen. When the Doctor, Sarah Jane, and Harry arrive, they are thrust into the middle of an apparent plague and must slowly uncover the tangled web beneath it before they can even begin to try and save the Vogans as well from the arriving Cybermen.
Jupiter in your Backyard
The real Jupiter is easy to find; all you have to know is where it is at a particular time, and any star map service can help with that.. Right now, it is in the constellation of Gemini, which rises after Orion does. If you can find Orion, Jupiter will be the brightest star not terribly far away from Orion. Don’t confuse it for Sirius, though, which is also up. To distinguish them, Sirius is notorious for twinkling, while Jupiter generally does not. Also, Jupiter will be brighter, and if you have binoculars or a small telescope, you may be able to see at least three of the Galilean moons. (All four are visible in small telescopes, but they aren’t always in the field of view; they aren’t visible when they’re passing behind Jupiter, or even when passing in front unless you have a large telescope and good seeing.)
The Galilean Moons are a real revelation to newcomers to backyard astronomy. You get a momentary sensation of what Galileo must have felt when he first spotted them. They appear in a tidy line along Jupiter’s equator, moving rapidly enough that if you look again a few hours later, it’s possible to see significant movement. This allowed Galileo to conclusively prove that some existed which definitely did not orbit the Earth, because it’s so obvious that these four large moons orbit Jupiter. From inside to outside, these moons are Io, Europa, Ganymede, and Callisto, although identifying which is which will take time to plot out their motion — or you can simply refer to a resources such as Sky and Telescope’s handy-dandy Jupiter moon utility, which shows you where they are at any given time and also lets you know of upcoming events such as moons going behind Jupiter or shadow transiting the disk (although you need a large telescope to see the small shadows).
The other great thing to observe with Jupiter is its atmosphere. The atmosphere is divided out into bands, which are usually visible even in relatively modest telescopes, and then of course there is the Great Red Spot. Jupiter takes about eleven hours to complete one full rotation, so you also need good timing to see the Great Red Spot. Fortunately, Sky and Telescope will help you with that as well. (Scroll down the page for their free Javascript utility; you have to get past their ad for the $2.99 iPhone app first.)
Jupiter is one of the most rewarding of backyard targets, after Saturn, and possibly the most historically important because of Galileo’s discovery of its four largest moons. So get on out there, take a look, and think of whether a mysterious extra moon might someday show up . . . .
Calli Arcale's Fractal Wonder 