The constellation Pisces sparked the imagination of Roman astronomers who pictured the mythical figures of Aphrodite and Eros tied together and swimming in opposite directions to escape the Typhon, one of the deadliest monsters of Greek mythology.
The “knot” that connects the two is the alpha star of Pisces, Alrescha, a double star system that can only be seen as two separate stars with high powered viewing equipment. The primary is a blue-white giant located about 142 light years from earth. Its a spectroscopic binary, meaning that another third star is nearby but can only be detected as their spectral lines shift. The companion star is blue-white as well and completes an orbit of the primary star every 900 years.
The large constellation of Pisces is in the daytime sky from March 12 to April 18 and can be seen at night from October to December, but not easily. To find Pisces, look for the alpha star of Andromeda to the north and the “square of Pegasus,” an asterism formed by the three brightest stars of the constellation Pegasus.