Astronomy news for the week starting Friday, April 9,
The Moon, just having passed its last quarter, wanes through its
crescent phase this week. It will be nicely visible in the morning
hours before dawn, and until the crescent gets too narrow, in
morning daylight as well. The Moon will then pass its new phase
the night of Thursday, April 15, and for two or three days will be
gone from the visible sky.
The morning sky also contains a view of Mercury, which will reach
greatest elongation west of the Sun on Friday the 16th. However,
because the ecliptic, the apparent solar path that is closely
followed by the planets, lies fairly flat against the morning
horizon this time of year, the apparition will not be very good,
Mercury never getting very high in morning twilight.
It is the evening planetary sky that beckons, as Venus climbs ever
higher while setting later and Mars rises ever earlier, the red
planet now climbing above the eastern horizon shortly after sunset.
Venus, continuing to brighten, is now making a very pretty passage
three or so degrees southeast of the Pleiades (the Seven Sisters)
star cluster. The two will be closest the night of Monday the
12th. The cluster makes a nice reference to see the movement of
the planet against the background stars as Venus clips along to the
northeast at close to a degree per day. The sight is well worth
photographing if you have a camera that can make time exposures.
The bright and beautiful Pleiades draw attention from other easily
visible clusters, the most prominent of which are the Hyades that
seem to surround Aldebaran (which is not part of the cluster) and
that make the "vee" of Taurus's head, now seen to the left of the
Pleiades in early evening. Try for a fainter cluster, the Beehive
(also called the "Praesepe," or "Manger") that sits smack in the
middle of dim Cancer. In a dark sky it appears as a faint smudge
almost exactly between the left side of Gemini and Regulus in Leo.
Binoculars will pick it up immediately. It is similar to the
Hyades in nature, but at a distance of 500 light years almost four
times farther away. At half the Beehive's distance is the
constellation Coma Berenices, mentioned last week, seen as a lacy
sprawl of stars south of the Big Dipper, the middle five stars of
which are yet another very nearby cluster that actually surrounds