On these late summer evenings
after the Sun has set, look low in the south for the classical Archer, Sagittarius.
Traditionally a centaur
(half man, half horse), it's one of two such creatures in the sky. The other
is Centaurus, a large, complex star pattern best viewed during the spring from
far-southern localities. Long ago Sagittarius was not a centaur at all but simply
a standing Archer (looking with some apprehension toward the Scorpion immediately
to his west).
About two-fifths of the
way up from the star Al Nasl northwest to Theta Ophiuchi lies the direction
of the center of our Milky Way system, appearing as a veritable cloud of stars.
The English poet John Milton (1608-1674) once wrote of the Milky Way as a "broad
and ample road whose dust is gold and pavement stars." This is "Our
Galaxy," to be spoken with pride, just as we would say, "My house."
Via Lactea is the Latin for our star system's appearance in the sky. For the
same reason, the Greeks used gala and kyklos, meaning milk and circle - hence
our word galaxy.
Although tracing out an
Archer-Centaur among Sagittarius' stars does require some imagination, visualizing
it as a Teapot is quite easy. In fact, it is the Teapot and not the Archer that
is portrayed on most star charts and in observing guides. I myself find it a
truly delightful pattern: as star pictures go it's one of the best. More than
a quarter century ago, the late astronomy popularizer, George Lovi (1939-1993)
pointed out that we could augment our tea service with a teaspoon and lemon
as well!
Lovi's teaspoon comprises
stars in northern Sagittarius, while his lemon is an alternate rendition of
the striking, albeit faint constellation of Corona Australis, the Southern Crown.
Now would also be a good
time to make comparisons of the Southern Crown with its northern counterpart,
Corona Borealis, located high in the west.
The main difference between
the two is that the southern one is a fainter and tighter pattern; its brightest
members are only of 4th magnitude (on this inverted scale, the dimmest stars
visible to the naked eye are about magnitude 6.5). The brightest star of Corona
Borealis, on the other hand, is 2nd-magnitude Alphecca.
Unfortunately, for most
of the United States, the Southern Crown is quite close to the horizon; from
New York it barely gets 10 degrees above the horizon, where
horizon haze becomes significant. One has to go as far south as Florida or the
Gulf Coast to get a really good view of it.
Both crowns are ancient
constellations, part of Claudius Ptolemy's (roughly 87-150 AD) "definitive"
list of 48 groupings that were handed down to Western peoples from that era.
Corona Borealis is the gem-studded golden crown of Ariadne, who, in Greek legend,
received it from Bacchus upon marrying him.
Corona Australis was originally
a group that represented a crown of leaves sometimes worn by the ancients on
ceremonial occasions. The Southern Crown, however, has no particular story associated
with it, although some write that it was another crown that Bacchus gave as
a gift, this one to his mother Semele.

Map the Milky Way!
Starry Night software
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Joe Rao
serves as an instructor and guest lecturer at New York's Hayden Planetarium.
He writes about astronomy for The New York Times and other publications, and
he is also an on-camera meteorologist for News
12 Westchester, New York.
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DEFINITIONS
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Degrees
measure apparent sizes of objects or distances in the sky, as seen from
our vantage point. The Moon is one-half degree in width. The width of
your fist held at arm's length is about 10 degrees.
1 AU, or astronomical
unit, is the distance from the Sun to Earth, or about 93 million miles.
Magnitude is
the standard by which astronomers measure the apparent brightness of objects
that appear in the sky. The lower the number, the brighter the object.
The brightest stars in the sky are categorized as zero or first magnitude.
Negative magnitudes are reserved for the most brilliant objects: the brightest
star is Sirius (-1.4); the full Moon is -12.7; the Sun is -26.7. The faintest
stars visible under dark skies are around +6.
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