Skylights featured four times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. A Moon for Spring.
Astronomy news for short week starting Friday, April 11, 2003.
This is the week of the full
Moon, the phase taking
place on Wednesday, the 16th, during the day and well before
Moonrise in North America. The closest view to the full Moon will
therefore rise just after sunset the night of the 16th, the
approaching-full rising just before sunset the night of Tuesday,
the 15th. Less than a day after full, the Moon passes perigee,
when it is closest to the Earth, the combination raising especially
high
tides at the coasts.
All the full Moons have traditional names, this one called the
Grass Moon, the Egg Moon, the Planter's Moon. Full Moon is the
best time to view the lunar maria (or "seas"), the dark spots that make
the "man in the Moon." Never real "seas," the maria are dark lava
flows that fill in ancient impact basins. All have names, the
prominent one near the top to the east of center "Mare Imbrium,"
the "Sea of Showers," never mind that the Moon has essentially no
water, all the names now just whimsical. Through the telescope,
the famed craters all but disappear, as the Sun is directly
overhead on the Moon's center, and there are no shadows to outline
them.
The evening sky is highlighted this week by
Mercury, which reaches its greatest eastern elongation, 20
degrees to the east of the Sun, on Wednesday the 16th. Though
bright, the little planet will still be difficult to find, as it
will be very low in the west in evening twilight. Better to admire
Saturn, seen to the west in eastern Taurus as evening begins, and then very bright
Jupiter, which is high to the south in fading evening twilight.
The morning sky is the domain of the two planets that flank the
Earth:
Venus and
Mars, which are quickly separating. Venus, still very bright
and noticeable, is now rising in the east rather well after
twilight begins, while Mars is now rising in eastern Sagittarius around 2:30 AM Daylight
Time.
That icon of the northern skies, the Big Dipper, now rides nearly overhead in late evening,
as seen from the middle northern latitudes. Bisect the handle to
the south, and you pass through a pair of stars that represent the
modern constellation Canes
Venatici, the "Hunting Dogs." Farther to the south you run
into a filigree of stars called Coma
Berenices (Berenices Hair), a real cluster whose stars are
bound together by gravity. So in fact are the middle five stars of
the Big Dipper, which together form the core of a cluster that is
slowly breaking apart.
