Now You See It, Now You Don’t - The Stones and the Stars: Building Scotland's Newest Megalith - page 14

2. Now You See It,
Now You Don't
How great is the power in the intersection of circles!.
- Astophon, Mineralium Constellatorum , quoted
by Giordano Bruno [ 1 ] .
Imagine that the Sun is a perfectly clear transparent globe,
and that an observer is stationed at its heart. It would be a remark-
ably peaceful place to be (neglecting what would happen if the Sun
really became transparent). All around there would be stars, so far
away that they would seem to be fixed to the inside of a sphere
that rotated very slowly around the observer with a period of just
over 25 days, as the Sun itself rotated on its axis. It would be obvi-
ous that the band of the Milky Way ran right around the sky and
was much thicker on one side than on the other; if the observer
had a sufficiently accelerated time-sense, so that millions of years
passed in what seemed to us like seconds, then he or she would
realize that all the stars were circling around an invisible center
of mass in the thickest part of the Milky Way. Before the first
230-million-year revolution was over, he might have deduced that
the visible part of the system was disc-shaped, and that the Sun's
orbit lay well out towards the edge of the disc.
If, however, his time-sense was a thousand times slower
than that, the changes would seem much more gradual. The Sun's
motion relative to the surrounding stars is a mere 12 miles/s, and
the local scenery would change much more slowly. He would real-
ize, as the thousands of years ticked past, that the stars near Vega
were gradually separating one from another, and that those on the
other side of the sky were gradually drawing together. A few stars
would show perceptible motion. Arcturus, for example, would
be seen creeping towards the southwest corner of Boötes. The
configuration of the Plough, a.k.a. the Big Dipper, would gradually