Photo of the Week. Venus and Jupiter in twilight, two
days before their wonderful 2012 conjunction.
Astronomy news for the week starting Friday, May 5, 2012.
We always start our Skylights with the meanderings of the Moon, the word not really apt as the Moon
hardly wanders but moves in a precisely known way. The path,
though, is complex, as it is strongly influenced by the gravity of
the Sun, which can
speed the Moon up in parts of its orbit, while slowing it down in
others, all the time stretching and bending the lunar path.
Speaking of the Moon, this is the week of the full Moon, which takes place the night of Saturday,
May 5, with the lunar disk high in the sky, its luster blotting out
the fainter stars, only the bright ones and three bright planets
shining through. This May full Moon takes place among the dim
stars of Libra well to the east
of the Spica-
Saturn pair, and is charmingly known as the Planting Moon, Milk
Moon, or Flower Moon. Oddly, the Moon passes through its perigee within
an hour of going through full, making it bigger and brighter than
usual. But not by that much, the only really visible effect the
strengthening of coastal tides.
See if you can spot the slight out-of-roundness of the waxing gibbous the night of Friday the 4th.
The remainder of the week past full the Moon then spends waning in the gibbous phase as it approaches
third quarter on Saturday the 12th. The
morning of Monday the 7th finds our companion in Scorpius just to the northwest of Antares while the following morning
finds it to the northeast of the star. On Wednesday the 9th, the
Moon passes over Pluto as
seen from Antarctica, a non-event if ever there was one.
But back to the three bright planets, all of which are viewable in
the evening. Venus, which has
now just passed its maximum brightness (though just barely), slowly
begins to slip away, now setting a bit earlier, but still after 11
PM. The planet's lustrous brilliance renders it easily visible in
modestly-bright twilight. Then transiting the meridian to the south just after sunset,
Mars (at magnitude zero,
still very bright) glides down the western sky, to the east of Regulus in Leo, until it sets around 3 AM. Coming in third (but
not by much) is Saturn. In the southeast at the end of twilight to
the northeast of Spica, the ringed planet transits the meridian
near 11:30 PM and does not set until mid-dawn. The week is also
marked by the annual Eta Aquarid meteor
shower. Peaking the morning of Sunday the 6th, these leavings of
Comet will be pretty much obscured by the bright Moon.
Aside from the Moon and planets, Leo still dominates the early-
evening scene. As the Lion stalks to the west, it, with Regulus
and Mars, is replaced by Virgo
with Spica and Saturn. Then look high into the early-evening
eastern sky to admire great Arcturus and its shining orange
light, the star the brightest of the northern hemisphere.