news sciences: Pisces? Here’s your constellation

Antique colored etching of two fish tied together by the tails.

Pisces the Fishes illustration courtesy of Old Book Art Image gallery.

Pisces the Fishes is sometimes called the first constellation of the zodiac because the sun appears in front of this constellation at the time of the March equinox. One tropical year is usually defined as the period of time between successive March equinoxes. So – in this sense – the March equinox marks the beginning of a new year. And that is why Pisces – backdrop to the sun on the March equinox – often appears as marking the starting point of the zodiac.

Sky with stars and constellation Pisces outlined.

As seen from mid-northern latitudes, the constellation Pisces appears in the southeast as darkness falls in November. Photo via Till Credner, AlltheSky.com.

When can I see the constellation Pisces?
In our time, the sun’s annual passage in front of the constellation Pisces is from about March 12 to April 19. Then the sun passes in front of the constellation Aries from about April 19 to May 14.

Of course, March and April are not good for seeing Pisces because this constellation is lost in the sun’s glare at that time of year. Instead, a Northern Hemisphere autumn (or Southern Hemisphere spring) – say, November – presents an opportune time for viewing Pisces in the evening sky.

As seen from across the globe, Pisces reaches its high point for the night at about 10 p.m. local standard time in early November and at about 8 p.m. in early December.

You need a dark country sky to see this fairly dim constellation swimming in what the early stargazers considered to be a watery region of the lore-laden heavens. Pisces is found to the northeast of the constellation Aquarius the Water Bearer and to the northwest of the constellation Cetus the Sea-monster.

Fortunately, Pisces can be found rather handily by referring to the signpost known as the Great Square of Pegasus, as shown on the sky chart below. Look first for the Circlet of Pisces – otherwise known as the head of the Western Fish – to the south of the Square of Pegasus. Once you’ve found the Western Fish, go on from there to catch the Eastern Fish that’s jumping upward to the east of the Square of Pegasus. The entire constellation looks like the letter V, and a very graceful and lovely V at that. The Alpha star of the constellation (though not the brightest star) is Al Risha. By the way, as seen from the northern tropics or the Southern Hemisphere, the Eastern Fish appears to be plunging downward.

First find the signpost known as the Great Square of Pegasus. That’s your jumping off spot for finding Pisces’ place in the great celestial sea. Click here for a larger chart.

Part of Pisces, the Circlet in Pisces, and the Great Square of Pegasus by Susan Jensen in Odessa, Washington. Thank you, Susan.

Pisces’ lone Messier object.
Pisces can only claim one Messier object – that is, a fuzzy object resembling a comet but really a star cluster, nebula or galaxy – within its borders. It’s Messier 74, a face-on spiral galaxy looming at an estimated 35 million light-years distant. In the month of March, when it’s technically possible – yet difficult – to see all the Messier objects in the span of one night, this Messier object in the constellation Pisces is one that is commonly missed.

Messier 74 as seen by the Hubble Space Telescope. Photo credit: NASA,ESA and the Hubble Heritage

Messier 74 as seen by the Hubble Space Telescope. Image via NASA

There are two reasons why Messier 74 is so hard to catch during the annual Messier Marathons in March and/or April. At that time of year, Messier 74 lurks rather low in the western sky at nightfall and quickly sinks out of view shortly thereafter. Plus, this distant galaxy has an extremely low surface brightness, so excellent seeing conditions are absolutely critical for catching Messier 74. You don’t need a large telescope as much as you need a dark, transparent sky.

But if you want to nab this faint galaxy that is Messier 74, the months around November are a grand time of year to do so. Try, possibly with averted vision, on a dark, clear moonless night.

Ruins of Palmyra, ancient Syrian city to the northeast of Damascus. Image via Wikimedia Commons

Pisces in mythology and star lore.
Greek and Roman versions of Pisces’ sky lore seemed to have come from Syria, where fish were regarded as divine. There seems to be some confusion as to whether the ancient Syrians abstained from fish altogether or only fish from the Chalos River (presently called the Queiq or Aleppo River).

The Syrian goddess of love and fertility, Atagartis, is often portrayed as half woman and half fish. She is thought to be the origin of the Greek goddess Aphrodite and the Roman goddess Venus.

According to Greek mythology, the fire-breathing monster Typhon was about to devour Aphrodite (the Roman Venus) and her son Eros (the Roman Cupid), except that they turned into fish and jumped into the Euphrates River to make a great escape. Mother and son tied themselves together with a cord to make sure they would not lose one another in the tumbling waters.

1948 night sky star map showing the constellations of the ancient Sea imagined by the ancients in this part of the sky. Look for the Western Fish swimming along the celestial equator, to the northeast of Aquarius and the northwest of Cetus. Image via etsy.com

How long is the Age of Pisces?
By some definitions, we’ll continue to live within the Age of Pisces as long the sun shines in front of this constellation on the March equinox. By the way, although the sun hasn’t appeared in front of the constellation Aries on the equinox for over 2,000 years, we still refer to the March equinox point as the First Point in Aries.

If we accept the constellation boundaries as defined by the International Astronomical Union, the Age of Pisces started in 68 B.C. and the Age of Aquarius will begin in 2597.

But there are many varied views on this, some of which you can read about in this post: When does the Age of Aquarius begin?

Bottom line: How to see the constellation Pisces. Plus sky lore and science.

from EarthSky https://ift.tt/37Tstjn