•2000 years ago
everything was far simpler.
•The only detector in use was the naked eye.
•The magnitude
scale only had to deal with a range of less than three
orders of magnitude in brightness – the
difference between Sirius and the faintest star visible
to the naked eye.
•Now
the magnitude scale must cover »55 magnitudes
(11 orders of magnitude in brightness)
from the Sun – magnitude –26.7 – to the
faintest stars detectable with the Hubble.
•And it has
extended to other ranges than the visible.
