Astronomy news for the week starting Friday, April 17, 2009.
Hitting third quarter as Skylights begins
on Friday, April 17, the Moon then spends the rest of the week in
its waning crescent phase.
When viewed at the same morning hour, it plunges ever further
toward the eastern horizon. The waning crescent then makes its
last show for the month the morning of Thursday the 23rd, just
before it goes to new Moon the night of Friday the 24th.
As the crescent thins, it will make lovely displays with
Jupiter and
Venus. The morning of Sunday the 19th, the Moon will appear
just to the west of the giant planet. The next two days finds it
between Jupiter and its much brighter neighbor. Then the morning
of Wednesday the 22nd, the crescent will make an unforgettable
sight just to the right of Venus. The two pass so close that,
during the day, the Moon will actually occult the planet. While
passing between the two bright planets, the Moon will also pass
north of
Neptune on Sunday the 19th, then north of Uranus
on Wednesday the 22nd, and finally, just after the conjunction
with Venus, north of Mars.
Rather obviously, we have quite a gang of planets in the eastern
morning sky. Jupiter, rising around 3:30 AM Daylight Time, is the
first of them to become visible, staying that way in the southwest
until growing twilight takes it away. Then just before 5 AM, Venus
lofts itself up above the horizon, staying visible well after
Jupiter fades away. On Saturday the 18th, Venus then passes
several degrees to the north of Mars. Much less visible than the
bright pair, the red planet does not even rise until half an hour
after the onset of dawn.
But don't forget the evening and Saturn, which
transits the meridian to the south
around 10:30 PM. It then stays visible in the western sky
until it sets just about the time Venus rises. For about an hour,
the ringed planet and Jupiter are visible at the same time as they
rule opposite sides of the celestial
sphere. In the evening, you might also watch out for little
Mercury, which pops up in twilight.
This week we celebrate the Lyrid meteor
shower, which radiates from the environs of Lyra, the little constellation (dominated by bright Vega) rising high to the northeast in
the morning hours. The shower, which typically gives us perhaps a
dozen meteors an hour (but is capable of much more), peaks the
morning of Wednesday the 22nd. Known for fast meteors, the shower
comes from the leavings of Comet
Thatcher of 1861, a long-period comet that will not return for
another 270 or so years.
After finding Saturn, look to the west for Regulus, then skip just a bit
farther to the west to view the irregular head of Hydra, the Water Serpent. The longest
constellation in the sky, Hydra then winds to the east beneath Leo and Virgo (with
Crater and Corvus in between), and finally ends just to the west
of Libra.
