In praise of Pisces: a dim zodiac constellation offers some surprising attractions.
Even so, I write in praise of Pisces. I'm going to explain why even its dimness can be part of the pleasure we find in observing it. But there's much else of mental interest to ponder, and visual interest to observe, in this constellation of the (two) Fish.
Reclaiming the heritage of naked-eye Pisces. How easy is it to see anything in Pisces with the naked eye if you have a heavily light-polluted sky? Not very. The only two stars brighter than magnitude 4.0 in the constellation are Eta ([eta]) and Gamma ([gamma]) Piscium (magnitude 3.6 and 3.7, respectively).
Fortunately, that's not all there is to the story of observing Pisces. For instance, there are about 10 stars (one is a variable) between magnitude 4.0 and 4.5 in the constellation--and, of course, many more of 5th and 6th magnitude. This number begins to suggest how beautiful it is to experience with the naked eye a constellation like Pisces in a truly dark sky--the environment in which it was originally seen and created.
When you see Pisces in a dark sky you can start to reconnect with earlier skygazers and all of the wealth of observation, legend, and cultural tradition they found in the faint fish. This is not only one of the constellations of the zodiac, it's the one which today contains the vernal equinox point in the heavens. Think of the history and tradition we can regain in Pisces when we travel to a dark sky or succeed in reducing light pollution somewhere. Binoculars can help show the stars of Pisces if your sky is too bright, of course. But there's no replacement for the wide and natural naked-eye view.
Tracing the two fish and cord. First, trace out the Circlet asterism of stars that forms the head of the western fish of Pisces, right under the much brighter Great Square of Pegasus. Then scan east until you find a southeast-curving line of seven stars that begins just before the 1h line of RA and ends just after the 2h line. Less than 2[degrees] south of the second star in the line, Epsilon (s) Piscium, is a special treasure this month: the magnitude-5.7 planet Uranus. The seventh star along the curve is magnitude-4.3 Alpha (a) Piscium. It's most often called Alrescha or Risha, which means "the rope," hearkening back to an old legend in which the Great Square of Pegasus was a bucket attached to a rope. The star has also been called Okda, "the knot" in the cord connecting the two fish of Pisces.
You'll need quite dark skies to follow the line of the northern fish from Alrescha up to Andromeda. The triangular head of the northern fish is not far from the great but sometimes elusive M33, the Triangulum Galaxy. In the body of the northern fish shines Eta Piscium, which can be found by running a line from magnitude-2.0 Alpha Arietis (Hamal) through magnitude-2.6 Beta ([beta]) Arietis (Sheratan) and extending the short line several times its length. Why would you want to find Eta Piscium? For one thing, it's a guide to Pisces' only Messier object: M74, just 1 1/2[degrees] north-northeast of the star. M74, a lovely but low-surface-brightness spiral galaxy, is the first object everyone must find in March Messier marathons.
Mystery-hued doubles of the double fish. We can't pretend that Pisces is rich with bright galaxies, clusters, or nebulae. It very definitely isn't. But an overlooked type of deep-sky wonder in the underappreciated fish is its marvelous double stars. If you don't use too much aperture, you may be able to detect their tints. Do you see a hint of green in the brighter component of tight Alrescha (magnitudes 4.2, 5.1)? Wide lovely duos in Pisces include [Psi.sup.1] ([[psi].sup.1]) Piscium and Zeta ([zeta]) Piscium. Fairly close pairs are 55 and 65 Piscium. And if you're looking for color, don't forget the very red 5th-magnitude variable star TX Piscium, on the edge of the Circlet.
Fred Schaaf welcomes your comments at email@example.com
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|Title Annotation:||OBSERVING: Northern Hemisphere's Sky|
|Publication:||Sky & Telescope|
|Date:||Nov 1, 2015|
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