Pisces, the Fish
swim in the ocean of
the sky where also can be found the sea monster Cetus. Nearby
to the west along the ecliptic, Aquarius, god of the waters, may
be seen as he pours out water to bring the gentle rains without
which the Earth would be fruitless. (However, it was he who also
caused the flooding of the Nile.) Above the swimming fish and
to the west, look for the flying horse, Pegasus. The Great Square
of Pegasus is one of the most prominent asterisms of autumn skies.
In the lore of the sky, these fish started out as gods. To the
Greeks, they were Aphrodite and her son Eros. The Romans knew
them as Venus and Cupid. A myth describes the mother and son strolling
along a river bank. They encountered a terrible giantTyphon.
Startled and frightened, Venus and Cupid jumped into the river
and assumed the form of fish. The other gods then elevated the
fish to the sky as one of the groups of the zodiac. The stars
were known as Venus and Cupid, in Roman times.
M74 is a
spiral galaxy seen face-on. It is typical of a grand-design
Sc galaxy. According to a classification scheme first worked out
by Edwin Hubble, the notations Sa to Sd refer to a simple spiral
form with a to d indicating increasing pitch angle. This galaxy
is at a distance of 30 to 40 million light years and is receding
at a rate of 800 km/sec. Along the spiral arms are clusters of
blue young stars. The spiral reaches out to cover a region of
more than 10 minutes of arc in diameter, corresponding to roughly
95,000 light years, about the same size as our Milky Way galaxy.
Discovered in 1780 by Messiers associate P. Méchain,
this faint object in Pisces was not determined to have its spiral
characteristics until 1848. In smaller telescopes it appears as
a fuzzy disk with a brighter center.
The constellation Pisces is a faint, but graceful and pretty pair
of delicate streams of stars which come together to form a V.
The point of the V is sometimes called the Heavenly Knot. Starlore
says its the knot that ties two fish together by their tails.
The two strings of stars diverging from the Knot culminate in
the diamond-shaped figure called the Northern Fish, and the Western
Fish, an attractive oval of fourth- and fifth-magnitude stars
called the Circlet. The Circlet can be easily found below the
Great Square of Pegasus.
The Vernal Equinox now lies in Pisces (originally this point where
the Sun crosses the plane of the ecliptic was in the constellation
of Aries). This is the point from which all right ascension coordinates
One of the brightest stars in Pisces is Al Rischa at the point
where the two fish are tied. In fact, the name comes from the
Arabic word for cord. Al Rischa, a-Piscium, is really
a double startwo stars af magnitudes 4.2 and 5.1 that orbit
each other once every 720 years or so. Its interesting to
note that the two stars whose name means cord really
are tied togetherby the long cord of gravity. With a separation
of just 2 seconds of arc, this pair is a challenge for small telescopes,
but the rewards justify the effort, for the stars are green and
blue, with remarkable contrast.
Within the constellation lies one of our closest celestial neighbors.
The faint star known as Wolf 28 is also called Van Maanens
star, named for an astronomer who discovered the star in 1917,
Adrian Van Maanen. He noticed that the star appeared to move quickly
across the sky relative to other stars, indicating that it was
nearby. Van Maanens Star is only 14 light-years from the
Earth. Only a few stars are closer. Its a white dwarfa
star thats used up its nuclear fuel. Our own Sun will become
a white dwarfin another five or six billion years.
First seen in the late 1960s, a bizarre class of objects called
gamma ray bursters can outshine the entire gamma-ray sky. For
them to appear so bright, they must result from cataclysmic eventsalthough
theres no consensus about their nature. The puzzle became
even more complicated in February, 1997, when the orbiting Compton
Gamma Ray Observatory and another spacecraft detected a burst
in the constellation Pisces that lasted for an hour and a half50
times longer than any other burst ever detected. Its energy level
was 12 times stronger than any other burster. The burst might
have come from matter spiraling into a black hole billions of
light-years away or possibly from a collision between two neutron
stars. But no one knows for sure.
Beginning in August bc7 there occurred in Pisces a rare triple
conjunction of the planets Jupiter and Saturn. Three times in
a single year these bright celestial objects appeared close to
each other. Could this event have been the Star of Bethlehem?