Philosophy [nature] is written in that great book which ever is before our eyes -- I mean the universe -- but we cannot understand it if we do not first learn the language and grasp the symbols in which it is written. The book is written in mathematical language, and the symbols are triangles, circles and other geometrical figures, without whose help it is impossible to comprehend a single word of it; without which one wanders in vain through a dark labyrinth.
At the base of the immense pillar, tiny Babylon was in shadow. Then the darkness climbed the tower, like a canopy unfurling upward. It moved slowly enough that Hillalum felt he could count the moments passing, but then it grew faster as it approached, until it raced past them faster than he could blink, and they were in twilight... For the first time, he knew night for what it was: the shadow of the earth itself, cast against the sky.
Algol is the name of the winking demon star, Medusa of the skies; fair but deadly to look on, even for one who is already dying.Ah, the bright stars of the night.Almost they obliterate the clear white pain. A thousand stars shining in the ether; but no dazzling newcomer. And so little time left, so little time...Yet still two-faced Medusa laughs from behind the clouds, demanding homage. Homage, Medusa, or a sword, a blade sharper than death itself.The wind stirs. Night clouds obscure the universe. A lower music now, a different kind of death.No stars tonight, my love.No Selene.
Before we invented civilization our ancestors lived mainly in the open out under the sky. Before we devised artificial lights and atmospheric pollution and modern forms of nocturnal entertainment we watched the stars. There were practical calendar reasons of course but there was more to it than that. Even today the most jaded city dweller can be unexpectedly moved upon encountering a clear night sky studded with thousands of twinkling stars. When it happens to me after all these years it still takes my breath away.
There is nothing particularly special about that location of the centre of mass. If you were to find yourself at the precise spot that is the centre of mass of the earth-moon system, the only thing unusual that you would notice is that there would be one thousand miles of rock on top of your head.Pluto is only about twice the size of Charon, so if you put Pluto and Charon on the cosmic seesaw you would find that the balance point is a little bit outside Pluto, rather than inside it. Again, there is nothing particularly special going on there. If you were to find yourself at that precise spot, you would only notice that you were very, very cold and could no longer breathe.
Let's grant that the stars are scattered through space, hither and yon. But how hither, and how yon? To the unaided eye the brightest stars are more than a hundred times brighter than the dimmest. So the dim ones are obviously a hundred times farther away from Earth, aren't they?Nope.That simple argument boldly assumes that all stars are intrinsically equally luminous, automatically making the near ones brighter than the far ones. Stars, however, come in a staggering range of luminosities, spanning ten orders of magnitude ten powers of ten. So the brightest stars are not necessarily the ones closest to Earth. In fact, most of the stars you see in the night sky are of the highly luminous variety, and they lie extraordinarily far away.If most of the stars we see are highly luminous, then surely those stars are common throughout the galaxy.Nope again.High-luminosity stars are the rarest. In any given volume of space, they're outnumbered by the low-luminosity stars a thousand to one. It's the prodigious energy output of high-luminosity stars that enables you to see them across such large volumes of space.