Astronomy news for the two weeks starting Friday, March 13,
2015.
The next skylights will appear March, 27, 2015.
Skylights' current two-week period is the result of travel and
medical issues. I hope to go back to weekly reports. Thanks for
your patience.
The fortnight is bracketed by the lunar quarters, third quarter passed on Friday, March 13, first quarter on Friday, March 27. In
between, the Moon first diminishes in the waning crescent phase, then passes new on
Friday the 20th, after which it grows in the evening through the
waxing crescent, all giving us a fine
show. At its new phase, the Moon usually passes above or below
the Sun, compliments of the five degree orbital tilt to the ecliptic (the path of the Sun
against the background stars). Not this time. Instead, it glides
right across the solar disk to produce a total eclipse. Unfortunately, totality avoids
significant land masses, crossing from the North Atlantic into the
Arctic. The partial eclipse also avoids North America, though it
will be widely seen in Europe and Asia. The Moon goes through perigee, where
it is closest to Earth, on Thursday the 19th. Proximity to
perigee is one of the requirements for a total eclipse. Were the
Moon near apogee (farthest), it would appear too small in angular
extent to cover to solar disk, resulting in an annular eclipse.
Third quarter will appear well to the left of Saturn. Look for the reddish star Antares of Scorpius down and to the right of the Moon. A far
better show will take place on the evening of Sunday the 22nd,
when the waxing crescent will make a beautiful pairing with
brilliant
Venus, the planet to the right. The night before, the Moon
will be paired with Mars, the red planet still setting around 8 PM with
the end of twilight catching up with it.
Jupiter still
sits near the Leo-Cancer border to the west of Regulus. Watch as it crosses the
meridian to the south in mid evening.
Jupiter has been in retrograde
(backward, east to west) movement against the stars since late
last year. And now it is Saturn's turn, as it enters retro on
Saturday the 14th, the ringed planet rising shortly after
midnight.
The really BIG event is the passage of the Sun across the Vernal Equinox in Pisces at 5:45 PM Central Daylight
Time on Friday the 20th, which marks the beginning of northern
hemisphere spring, the event oddly taking place at almost the same
time as the eclipse. With the Sun on the celestial equator, it will technically rise
due east, set due west, be up for 12 hours and down for 12, rise
at the north pole and set at the south pole. In reality,
refraction by the Earth's atmosphere and that sunrise and sunset
are counted from the top of the Sun, not the center, extend
daylight slightly beyond 12 hours and cause the Sun to rise at the
north pole a bit in advance of equinox passage, etc.
As we pass into spring, the winter constellations (Taurus, Auriga, Orion, and
the rest) slowly exit to the west, though there is still plenty of
time to see them. By 9 PM, the eastern fringe of them, marked by
Gemini (with Castor and Pollux) and Canis Minor (with Procyon), lounge near the celestial
meridian. Later in the evening, follow the curve of the handle of
the Big Dipper to the south to
find orange Arcturus near the
southern end of Bootes (the
Herdsman). To the east of Bootes is the graceful curve of stars
that makes Corona Borealis, the
Northern Crown.
