The Sky This Month
Welcome to our night-time sky.
Please enjoy this month’s tidbits of
knowledge. We are lucky to live in
a dark-sky area where the heavens
can shine through. I hope you enjoy
the sky and perhaps learn a thing or
two. Happy star gazing!
Happy New Year! – On January
14th! Well, if you are in the
Christian Eastern Orthodox Church. They still follow the
Julian calendar, which was created by Julius Caesar in
46 BC. Prior to the Julian calendar, the Roman calendar
followed a complicated lunar measurement of 12 months
which equaled 355 days. An extra month of varying
length would be added to realign the calendar with
the solar year. To fix the problem, Julius modified the
calendar to include 365 days and then added a leap year
every four years. The trouble with the Julian calendar
is that the year is not exactly 365.25 days. It is a little
less. Consequently, the Julian calendar adds about three
extra days every four centuries. In 1582 Pope Gregory
XIII created the Gregorian calendar which reduced the
number of leap years by removing leap days in years
divisible by 100, but leaving leap days in years divisible
8 January 2018 pccnews
by 400. The new calendar (our current one) only loses
one day every 3,030 years. To keep everyone on track,
we now add a leap second every once in awhile as
determined by atomic clocks. So, if you missed the Rose
Parade, you can play the re-run on the 14th and all will
be well.
Polaris of the South – Navigators in the northern
hemisphere are easily guided by Polaris, the north star.
Polaris remains relatively stationary as the Earth rotates
below it. Sailors can use the star to mark North in the
evening. Sailors in the southern hemisphere are not so
lucky. Unfortunately, there is no comparable star in the
south that marks the direction of the South Pole. The
closest star is about one degree away, but it is extremely
faint at magnitude 5.45. The only consolation for sailors
is the Southern Cross. This constellation of five major
stars circles the South Pole and the bottom of the cross
always points toward the South Pole. In the year 66,270
sailors can rejoice. The Earth’s precession (wobbling on
its axis) will cause the poles to point in new directions. At
that time Sirius, the Dog Star, will be a mere 1.6 degrees
away from the South Pole.
—Brian Biggs
Amateur Astronomer