Photo of the Week. The Big and Little Dippers
swing around Polaris, toward
lower right. Draco winds between
the two, wrapping itself around the Little Dipper. Thuban is just up and to the left of
center. The reddish star just down and to the left of it is 10
(CU) Draconis.
Astronomy news for the week starting Friday, May 15, 2009.
As quiet as last week was, this one is busy. Begin with the third quarter
Moon, which takes place the night of Saturday, May 16th (actually
the morning of the 17th), roughly around the time of moonrise in
North America. The Moon then spends
the remainder of the week in its dimming, waning crescent phase, new
Moon not reached until Sunday the 24th. Watch as the slimming
crescent rises ever later in the morning hours and as Earthlight develops on the nighttime
side.
Following third quarter, the crescent then undergoes a remarkable
series of planetary conjunctions, beginning on the morning of
Sunday the 17th with Jupiter, when the rising Moon will be three
degrees to the north of the giant planet. Then look the morning of
Wednesday the 20th to find the Moon well up and to the right of
brilliant Venus. The next morning, that of Thursday the 21st,
presents an even better sight, with the Moon making a fine triangle
with Venus, which will now be down and to the right of it, much
fainter reddish
Mars down and a bit to the left. Formal conjunction between
the Moon and Mars takes place during the daytime. In between, the
Moon passes north of
Neptune the morning of Sunday the 17th and then takes on Uranus two days
later.
Clearly, the morning holds the planetary glory, with Jupiter now
rising just before 2 AM Daylight Time, Venus coming up around two
hours later, just before 4 AM, coincident with the onset of dawn,
by which time Jupiter has moved well into the southeast. Though
Venus passed its greatest brilliancy for the rest of the year, the
view continues to get better. On the other hand, the other planet
inside Earth's orbit, Mercury, is quite gone from
view, as it passes inferior conjunction (between us and the Sun, though not
directly) on Monday the 18th.
Switching over to the evening sky gives us Saturn.
Crossing the celestial meridian to the
south just around the time of sunset, the planet will have moved
into the western half of the sky by the time twilight fades enough
for it to be visible. Still in southeastern Leo to the east of Regulus along the ecliptic, Saturn finally stops
its
retrograde motion on Sunday the 17th, and ever so slowly begins
to move back in the other direction, to the east as it heads toward
the next constellation of the Zodiac, Virgo. Up a good part of the night, Saturn sets
between the rising times of Jupiter and Venus.
As twilight ends, the Big Dipper
of Ursa Major lies nearly overhead.
Farther down, the handle and bowl of the Little Dipper of Ursa Minor, marked well by prominent
Kochab and Pherkad, stretches up to reach it,
all circulating around Polaris,
which lies near the North Celestial
Pole. Find Mizar, the second
star in from the end of the Big Dipper's handle (while looking for
nearby Alcor, the two making the
Arab's "Horse and Rider"). Thuban, Alpha Draconis, which as a
result of precession was the pole
star some 4700 years ago, lies between the it and the Little
Dipper's bowl.
