Astronomy is primarily an observational science. It is driven
more by new observational discoveries than by interpretive insights.
Few important astronomical discoveries were predicted, and many were
actually accidental. The human imagination has never been a match
for the universe.
Astronomical discovery began with the simplest of observations: people
looking at the night sky and trying to understand what they were
seeing -- sometimes in awe and wonder, sometimes in fear of the
unknown powers at work in the heavens.
In the past, most people were well acquainted with the basic features
of the night sky. We are unfamiliar with the sky in modern times
mainly because of the advent
lighting, which makes it difficult to see the night sky in
urban areas (and also unnecessary to know the sky as a
This lecture introduces you to the basic features of the night sky which
are visible to the unaided eye and prepares you for the Constellation
1 degree = 60 minutes of arc;
1 arcmin = 60 seconds of arc Don't confuse these angular units with units of time! Always use the "arc" terminology for clarity.
[Note: the symbol ~ means "approximately"]
Angular scales of "pan" of Big Dipper
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Last modified June 2019 by rwoText copyright © 1998-2019 Robert W. O'Connell. All rights reserved. Opening fisheye lens picture of comet Hale-Bopp and night sky from Ujue, Spain, April 1997, copyright © J. C. Casado. Orion at horizon picture by B. Tafreshi. Illustrations of the celestial sphere copyright © by Nick Strobel. Image of M13 copyright © by J. Ware. These notes are intended for the private, noncommercial use of students enrolled in Astronomy 1230 at the University of Virginia.