Astronomy news for the two weeks starting Friday, April 22,
2016.
The next skylights will appear May 6.
The Moon fades away. Having gone through full the night of Thursday, April 21, it
spends the first week of our period in the waning gibbous phase. Passing third quarter the night of Friday the 29th,
it spends the second week as a waning
crescent, the phase terminated at new
Moon on Friday, May 6. On the night of Saturday the 23rd the
Moon will appear west of Mars and Saturn, while the following night it will fall west
Saturn and north of both Mars and the red supergiantAntares of Scorpius, the four making a ragged box. By the night
of Monday the 25th, the Moon will have moved to the left of the
planets, the three now making a pretty line.
The lunar orbit rather oddly tracks the phases. Thirteen hours
before full Moon last Thursday the 21st the Moon stood at its tides at the coasts
(a change of 11 percent in distance making the
ocean tides nearly some 35 percent larger,
high tide to low).
Jupiter
dominates the evening scene, crossing the meridian to the south about as full
darkness descends. Half an hour later Mars comes up, then, after
another half-hour, Saturn rises, the two nicely gracing the
southeastern sky as presaged above and making a triangle with
Antares below. After the Moon is out of the way, it's easier to
see the color similarity between Mars and its namesake Antares and
the contrast with yellowish Saturn, Mars's redness basically coming
from iron oxide in the "soil," actually the "regolith" as Martian
surface material carries no organic compounds, the by-products of
life. Or at least as we have so far found. In addition to these
bright planets we can count Mercury, which early in
the fortnight is making a good appearance (about as good as it
gets) in western evening twilight. But look early, because it's
quickly gone.
Keep your eye out for the Eta Aquarid meteors the mornings
of Thursday and Friday, May 5 and 6. With the Moon out of the way, the debris of Halley's
Comet may make a decent showing before dawn.
As spring advances, Orion and
his gang flee to the west. Early on though, we can still admire
the Hunter and his two dogs. The three constellations carry five first magnitude
stars: Betelgeuse and Rigel in Orion; Sirius and Adhara in Canis Major (to the south-southeast of Orion, Adhara
below Sirius); and to the east of Betelgeuse, Procyon in Canis Minor. Betelgeuse, Sirius, and Procyon make
their own group as the Winter
Triangle. The trio more or less encloses a faint modern
constellation, Monoceros, the
Unicorn. Above the Winter Triangle are the stars of Gemini with first magnitude Pollux and the brightest of second-
magnitude, Castor.
