Close-up of Castor and
Pollux showing the contrast in colors.
In March, Gemini - "The Twins"
- is high in the sky in the early evening. On closer inspection,
the twins, Castor and Pollux, are not identical. Castor is much
hotter than Pollux and as a result the color of castor is quite blue,
whereas Pollux is a yellowish tint. These colors are captured
with a digital camera aimed at the constellation. No telescope is
Saturn is very prominent in
Gemini this season. The Physical Science class has measured the
apparent motion of Saturn throughout December, January, and February
and observed that Saturn has been moving westward throughout the
season. The December 25 location is indicated.
fainter star Zeta Geminorum is an interesting star in that it varies in
brightness with a cycle of 10.2 days. During the past 6 weeks I
have been photographing Zeta Geminorum with the digital camera without
a telescope. Here is a graph of the brightness of Zeta as a
function of the fraction of a cycle. The brightness is measured
relative to the brightness of a nearby star to compensate for varying
atmospheric effects. The digital camera also permits a
quantitative measure of the color of stars. A plot of the color
shows a similar pattern because the temperature of a pulsating star
such as Zeta Geminorum oscillates. I am presenting these results
Saturday, Mar. 27 at the spring meeting of the NC Section of the
American Association of Physics Teachers.