Celestial News: What to see in October skies
October 5, 2018
October is a great month for sky watching. Darkness falls earlier than the summer months and the cool autumn evenings offer some of the clearest, darkest skies of the year.
Step outside around 8:30 p.m. any clear night during the first week of October and marvel at the sight of the starry band of our Milky Way Galaxy running from northeast to southwest and directly overhead.
The misty band of the Milky Way is composed of the light of billions of distant suns. Look closely and you can see dark rifts in the star clouds of the Milky Way, caused by vast clouds of obscuring star dust blocking the light of the stars behind them. If you sweep the band of the Milky Way with a pair of ordinary binoculars, you'll discover dozens of jeweled star clusters and colorful nebulae.
By the second week of October, the moon returns to the early evening sky, dimming the feeble light of the Milky Way, but creating a remarkable series of close conjunctions with the evening planets in return.
On Oct. 11, look west into the multi-colored sunset glow to catch the slender crescent moon hovering just 3 degrees from the brilliant Jupiter. The best time to look will be around 7:30 p.m., before the pair sets in the west, shortly after 8 p.m.
Three nights later, on Oct. 14, the noticeably fatter crescent moon will have an incredible, close encounter with the ringed planet Saturn. The two will appear only 1 degree apart in the southwestern sky. Be sure to catch them before they set around 10 p.m.
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When darkness falls on the night of Oct. 17, the red planet Mars and the waxing gibbous moon will pose together, just 5 degrees apart. The two will glide across the southern sky during the night, inching closer and closer together until they set in the southwest after midnight.
Perhaps the top celestial event of the month is the annual Orionid meteor shower, which peaks in the predawn hours of Oct. 21. There is a brief window between moonset and dawn that morning when dark skies could reveal up to 20 meteors, or shooting stars, each hour. The moon will set around 4 a.m., so there will be about two hours before dawn for great meteor watching.
Orionid meteors are so named because they seem to radiate out of the magnificent constellation of Orion, the Hunter. The Orionid meteors are actually tiny particles of dust shed by Halley's Comet centuries ago, striking Earth's atmosphere at such tremendous speeds that they completely incinerate in the streak of a shooting star.
The moon turns full on the night of Oct. 24. This second full moon of autumn traditionally is called the Hunter's Moon. It will shine all night long as it traverses the sky from east to west — full at dusk and full at dawn.
No special optical aid is required to enjoy these celestial events, just your own eyes. Step outside this month and explore the other half of nature that exists up over our heads.
Jimmy Westlake retired from full time teaching at Colorado Mountain College Steamboat Springs in 2017, after 19 years as their professor of physical sciences. His Celestial News column appears monthly in Steamboat Pilot & Today. Check out Westlake's astrophotography website at jwestlake.com.