Regulus (also called 'Alpha Leonis') is a /very/ bright star
located in the constalation Leo. In fact, it's the 21st brightest star
in the entire sky! There's two different ways that you can think about
how it moves. The first is really simple. Since the Earth rotates all
the time, it looks like the stars are moving overhead. So, just like
the Sun will rise in the East and set in the West, all the stars in the
sky will look like they move from the East to the West. But this
doesn't have to do with the star actually moving with respect to
Earth... just with the Earth spinning around its axis.
But, stars don't stay in exactly the same place all the time. Both
the sun and Regulus do move through space very slowly. A way of
measuring this is by looking at the 'declination' of the star.
Declination is a lot like latitude, only for things in space. It's
basically the same as if you figured out the latitude that you'd have
to be at for the star to look like it was straight above you.
In 1900, the declination of Regulus was +12.27'; in 1950, it was
+12.12'; and in 2000, it was 11.58'. This means that if you were
standing somewhere where the latitude is 12.27' in the year 1900 (like
if you were in Nicaragua), it would look like Regulus was straight
overhead. But as time went on, you'd have to move a little bit farther
North to keep it straight overhead. So in 2000, it looked like it was
just a tiny bit farther North than it did in 1900, as if it were slowly
moving from the South to the North.
(republished on 07/19/06)