Stars over Sisters

Of the 88 constellations that encompass the celestial sphere, 10 of them represent some form of aquatic creature. Most of us are somewhat familiar with three of them because they belong to the group of zodiac constellations: Cancer the crab, Capricornus the sea goat, and Pisces the fishes. The remaining seven stellar water animals are far less commonly known. It turns out, however, that September is a good month to view the smallest of them.

Depicted as a dolphin, Delphinus is situated between the constellations of Aquila the eagle to the west and Pegasus the flying horse to the east. The asterism is recognized by four stars that form a tight, flattened diamond. This represents the dolphin's body. A fifth star of about the same brightness lying to the southwest denotes its tail. The eastern-most star in the diamond that marks the dolphin's nose is also a very fine double star. Both stars have a yellowish hue and are an attractive sight when viewed through a telescope. The pair lies at a distance of about 100 light-years.

One of the most remote globular star clusters in our galaxy is found in Delphinus. At a distance of about 137,000 light-years, this object is almost as far away as the Milky Way's two satellite galaxies, the large and small Magellanic Clouds (visible only from the southern hemisphere).

Like many other constellations, Delphinus has a place in Greek mythology. The poet Arion of Lesbos was a court musician at the palace of Periander, ruler of Corinth. During his travels to Sicily and Italy, Arion had amassed a fortune. While on a trip home from southern Italy, Arion's wealth caused the crew of his ship to conspire against him. Threatened with death, the musician asked to be granted a last wish: he wanted to sing a song of goodbye. The crew agreed, and while singing Arion flung himself into the sea where he was rescued by a dolphin which had been charmed by the mournful sounds. The dolphin carried Arion safely to the coast of Greece.

Autumn begins at 7:49 a.m. PDT on September 22, when the sun crosses the celestial equator on its journey southward. The length of daylight and darkness is nearly equal everywhere on the earth at this time. The rate of change in going to shorter days and longer nights is also greatest at the fall equinox.

After dominating the evening skies for several months, Mars and Saturn hang very low in the west at nightfall as they begin to fade from the scene. Meanwhile, in the east Venus and Jupiter shine like brilliant beacons in the predawn sky.

The moon will become progressively less illuminated through the first half of the month; last quarter on September 8 and new on September 15. From here the moon brightens, reaching first quarter on September 22 and becoming full on September 29 - the Harvest Moon.