October 16, 2021: At the beginning of morning twilight, the bright stars of the Orion region of the sky shine brightly from the southern sky.
DAILY PLANET NOTES FOR OCTOBER 2021
by Jeffrey L. Hunt
Step outside at the beginning of morning twilight during mid-October. That is 90 minutes before sunrise for the mid-northern latitudes. With the later sunrise that occurs during October, these stars are visible at a more convenient hour.
Look into the southern sky for several bright stars, from Sirius that is low in the sky, to Capella nearly overhead. Half of the ten brightest stars visible in the night sky are found here.
Orion is the flagship constellation in this part of the sky, with its two bright stars, Betelgeuse and Rigel. Both stars are thousands of times brighter than our sun. Betelgeuse, shining with a rosy color, is about 500 light years away, while sapphire-white Rigel is nearly twice as far away.
The brightest star, Sirius, is to the lower left of Orion. The bright star is intrinsically dimmer than Betelgeuse and Rigel, but is less than nine light years away. The Dog Star is the seventh closest star to our solar system. The other half dozen are dimmer and semi-obscure catalog names, except for Alpha Centauri and Proxima Centauri – the closest star system.
Aldebaran is higher in the sky, while Capella is nearly at the zenith – overhead in the sky.
Procyon and Pollux are to the east of Orion and above Sirius.
The entire congregation of stars is seemingly pulled westward by the Pleiades star cluster. The stellar bundle is somewhat dim. It looks like a cloud and tends to catch your view when not looking directly at it.
The Orion region of the sky is found in the evening sky during the middle of winter. As Earth revolves around the sun, we see stars in different places in the sky at different times of night at various times of the year. They made their first appearances in the eastern morning sky during summer. Sirius first appeared in the eastern morning sky during mid-August.
During October they appear in the south before sunrise. Capella and the Pleiades are rising in the northeastern sky later in the evening.
By December, the Orion region is in the eastern sky after sunset. During February, they are in the south. As spring brings later sunsets, these stars are in the west after sundown, before they disappear into the sun’s glare during later spring and early summer.
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