Tag Archives: Equinox

Pisces (The fishes)

Constellation PiscesThis zodiacal constellation is a rather dim grouping of stars that are strung out low across the southern sky, just below the Great Square of Pegasus. Pisces is one of the 48 constellations cataloged by the 2nd century astronomer Ptolemy that remain among the 88 modern constellations. It is highest in the sky and best observed at nightfall in December. The intersection of the ecliptic and the celestial equator lie within this constellation. There are two such intersections that mark the two equinoxes. At the intersection in Pisces, the Sun is moving from south to north, so this is the point of the Vernal (spring) Equinox. This constellation is home to just one Messier object, M74.

IAU Pisces chart, IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg), June 5, 2011

© James R. Johnson, 2014

Virgo (The virgin)

Constellation VirgoVirgo, the virgin, is one of the zodiacal constellations,  is one of the 48 constellations cataloged by 2nd century astronomer Ptolemy, and is the 2nd largest constellation in the sky. It can be found at is highest point in the sky at nightfall in March. Virgo is located on the ecliptic, flanked by Leo and Libra. It can also be found by following the arc of the Big Dipper’s handle through Arcturus in Bootes to Spica (Alpha Virginis), Virgo’s brightest star. Some of Virgo’s remaining stars can be difficult to see in light-polluted urban skies because this is not a particularly bright constellation. Within Virgo is one of the two points where the ecliptic intersects the celestial equator.  The moment of the Sun’s southward crossing of the celestial equator as it moves along the ecliptic is the Autumnal Equinox, which marks the first day of Fall.

The Virgo Cluster is a very large scale object spanning about eight degrees and containing 1,300 or more individual galaxies. The cluster is centered in Virgo, and extends northward into Coma Berenices. The member galaxies that were cataloged by Charles Messier are M49, M58, M59, M60, M61, M84, M86, M87, M89, and M90. Many other galaxies in this cluster have NGC designations. The Sombrero Galaxy, M104, is a very unusual galaxy in Virgo that is not a member of the Virgo Cluster.

IAU Virgo chart, Sky & Telescope magazine (Roger Sinnott and Rick Fienberg), June 5, 2011.
IAU Virgo chart, Sky & Telescope magazine (Roger Sinnott and Rick Fienberg), June 5, 2011.

© James R. Johnson, 2014.