Re: Night Sky 101
- From: Llanzlan Klazmon the 15th <Klazmon@xxxxxxxxxxxxxxxx>
- Date: 27 Aug 2007 13:11:09 +1200
"wm.king@xxxxxxxxxxxx" <wm.king@xxxxxxxxxxxx> wrote in
news:1188044445.578325.80010@xxxxxxxxxxxxxxxxxxxxxxxxxxx:
A few very basic questions; I am quite clumsy with this sort of thing
and would be very grateful for nutshell answers:
1. Are the constellations unchanging? I.e., are those we see from a
given time and place (allowing for environmental conditions) the same
(or not perceptively different) than they would have been in 1984 or
1892?
To casual visual observation you would see no difference over that sort of
time scale. The fact that stars are not in fixed positions was first
discovered by Sir Edmund Halley. He noticed that the positions of the stars
Sirius, Arcturus and Aldebaran had noticably changed compared to the
positions reported by the ancient astronomer Hipparchus. These changes are
known as 'proper motion'. Modern instruments can now measure proper motion
for large numbers of stars and most star catalogues will list this along
with other information.
http://en.wikipedia.org/wiki/Proper_motion
2. Is there a website or reference book that will show you the night
sky from a gfiven time and place and identify the constellations?
Much better than a website would be one of the free planetarium programs
which you can download. A big advantage is that they work without having to
be connected to the internet. A couple of good ones for the windows OS:
Sky Charts:
http://www.stargazing.net/astropc/
Download the link about halfway down the download page that says 'Complete
Package 2.76'.
Stellarium:
http://www.stellarium.org/
This one is probably a better option for beginners. For either of these
programs you configure them with your location and they will show views of
the sky from that location at the specified time (within a few thousand
years of the present). You can zoom in/out print charts etc.
3. How much effect do the stars (excluding the moon (which I know is
not a star anyway, and again leaving aside environmental conditions)
have on how light it is at night?
On a clear moonless night well away from articficial lights and skyglow you
can actually see enough to move around once your eyes are fully dark
adapted.
Klazmon.
Thanks in advance.
Bill King.
.
- References:
- Night Sky 101
- From: wm.king@xxxxxxxxxxxx
- Night Sky 101
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