By Mike P. Usher
Coincidentally with the Fourth of July later this week, the stars are putting on their own special show. Scorpius (the scorpion) is both one of the brighter constellations in the zodiac as well as one of the few that looks like its namesake. Mythology of the constellation goes something like this: it is the scorpion that stung Orion to death; now that they are both in the heavens he is careful to keep as far as possible in front of the scorpion lest he be stung again. This is why they are never seen in the sky at the same time.
The bright star Antares is the red heart of the constellation. The name Antares in Greek means roughly “rival of Mars”, a reference both to its color and brightness. Antares is a type of star called a red supergiant, one of two visible to the naked eye, though a fair number are visible to those using binoculars. As is typical for a red supergiant it fluctuates slightly in brightness. Antares is also a double star, its companion being very much fainter, but being noticeably green in color. The companion was discovered by accident when the Moon passed in front of Antares blocking it’s brilliant glare and allowing the companion to shine out on its own.
Scorpius and Sagittarius (the archer) are both embedded deep in the Milky Way and consequently have vast numbers of star clusters of all shapes, sizes and kinds in them. As before, each tiny circle on the accompanying chart has an item of interest for those of you using binoculars. The brighter targets have identifying names or catalog numbers printed just above and to the right of the circle. Although it’s not labeled, see if you can find a literal cloud of stars in Sagittarius’ bow.
Many of the labels have NGC prefixes; this stands for New General Catalog. The catalog is not really new – it was compiled in the late 19th century; it remains however a popular guide for amateur astronomers as most of the objects are visible in an average amateur telescope and quite a few are visible in binoculars.
Although it is on the chart you can forget trying to find Pluto – it is far beyond the reach of your naked eye and even binoculars. At magnitude +13.99 it’s a target only for 10-inch telescopes or larger.
See you next time!
Mr. Usher is President of the Everglades Astronomical Society which meets every second Tuesday at 7:00PM at the Norris Center, Cambier Park, Naples.