Photo of the Week. The "glory" or "pilot's rainbow,"
caused by sunlight falling onto clouds in front of an airplane and
interfering with itself. The shadow of the plane can barely be
seen in the middle of the diffraction rings.
Astronomy news for the two weeks starting Friday, February 26,
The next skylights will appear March 11.
As we begin, the Moon wanes in the gibbous phase, which ends at third quarter on Tuesday, March 1, rather
well before moonrise in North America, as it turns into a waning crescent. That phase in turn ends at
new Moon on Monday the 8th, when it will totally
eclipse the Sun. But don't break out the eclipse glasses, as
the event takes place at night and is not generally visible in
North America, though Alaskans will get to see a poor partial
display. Hawaiians will witness a better partial eclipse near
sunset. In the aftermath is the waxing
crescent, which will first appear the twilit evening of
Tuesday the 9th.
The night of Sunday February 28 finds the waning gibbous Moon
northwest of Mars, while
the next night (that of the 29th: see below) we see the Moon to
the northeast of the red planet. The just-barely waning crescent
then takes on
Saturn, passing a few degrees north of the ringed planet the
night of Tuesday the 1st. During most of our fortnight the Moon
moves slightly closer to Earth, passing perigee, where it is closest, on
Thursday the 10th.
which passes opposition with the
Sun on Tuesday the 8th, is now visible all night long, rising
near sunset, setting near sunrise, and crossing the meridian to
the south (stuck in southern Leo) near
midnight just about as Mars rises northwest of Antares in Scorpius. Somewhat over an hour later, up comes Saturn
to the northeast of Antares, the two planets and the star making a
striking triangle. Venus, rising
in morning twilight just after Mars transits the meridian, has become a more difficult
catch, though it is still bright. The morning of Monday the 7th,
it will lie a few degrees south of the waning crescent Moon. Neptune
then makes a bit of news by passing conjunction with the Sun
on Sunday the 28th.
On Monday, February 29, we celebrate 2016 as a leap year, the
extra day tossed in to average out the length of the year at
365.25 days. This simple Julian calendar, however, does not quite
fit the real year of 365.2422... days. We get an almost perfect fit
in the Gregorian (our civil) calendar by dropping leap years in
century years not divisible by 400. The year 2000 was a leap year,
while 2100 will not be, which will undoubtedly cause trouble
within the calendar industry.
With Leo rising, recognizable by its sickle-shaped head, we can
turn our attention to the coming spring. Between Leo and Gemini lies dim Cancer with its Beehive
Cluster, while to the south of the celestial Crab is the head
of Hydra, the Water Serpent, which then
winds far to the southeast. But the winter constellations still dominate the early evening,
Orion to the south, Auriga with bright Capella
above his head. Through the telescope we can just barely resolve
Capella into two luminous
stars that circle each other every 104 days about as far apart as
Venus is from the Earth.