THE SEASONS
Eighty-eight formal constellations, named
patterns of stars, spread across the sky. Fifty were handed down
from the ancients, while another 38 were added in modern times by
explorers of the southern hemisphere and to fill in the blanks up
north. Countless informal asterisms are scattered among them.
Three are icons: the Big Dipper (part
of Ursa Major, the Great Bear), the Southern Cross, and one of the most
recognizable sights of the sky, Orion,
the Hunter of ancient Greece. He crosses high to the south during
northern winter. Straddling the celestial
equator, his bold seven-star pattern dominates the starry night.
In one story, he was killed by Diana, who was fooled by jealous Apollo
into thinking he was a deer. In another, he was done in by Scorpius, the Zodiac's scorpion, the gods then
placing him in the heavens opposite his nemesis.
At the upper left of Orion glows the magnificent red supergiant Betelgeuse, a dying star more than four
times the size of Earth's orbit, while at the lower right is the blue
supergiant Rigel. The names derive from
corruptions of ancient Arabic, respectively meaning the hand and foot
of the "Central One," a mysterious woman. Between them is his most
prominent feature, three bright stars in a row that make his Belt. To the Arabs they were a string of
pearls." To the upper right of the Belt lies Bellatrix, to the lower left Saiph. Both are blue-white in color. All
seven are massive enough to collapse internally and explode.
But don't worry, as they are hundreds of light years away (a light
year the distance light travels in a year at 186,000 miles per
second), too far for this most catastrophic of stellar events to
disturb us. Unlike most constellations, much of Orion is made of stars
related by birth a few million years ago. You can see some of the
birth process going on today. With binoculars, look down from the
Belt to the vertical three-star Sword. In the middle is a glowing
patch, the Orion Nebula ("nebula" Latin
for "cloud"), a vast remnant of the latest round of star formation. Some 20 light
years across, it's lit up by the ultraviolet light from a complex
set of hot massive stars called the "Trapezium" and is among the great
telescopic sights of the nighttime sky.
For previous "Astronomy Corners," go to
http://stars.astro.illinois.edu/sow/vvac.html
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Copyright © James B. Kaler, all rights reserved.
These contents are the property of the author and may not be
reproduced in whole or in part without the author's consent
except in fair use for educational purposes. First published in
the October-December 2015 Clark-Lindsey Village Voice.