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The Denver Observer September 2018

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The Denver Observer September 2018 The Denver SEPTEMBER 2018 OBSERVER New DAS member Steve Smith saw the chart for Vesta’s path through Ophiuchus in last month’s Observer, and pho- tographed the minor planet as it passed by the star c Ophiuchi on the evening of August 20th. Image © Steve Smith. SEPTEMBER SKIES by Zachary Singer The Solar System horizon, rising to about 7° some 15 minutes later. Look soon though, because the planet’s Sky Calendar If you’ve been watching the sky after 2 Last-Quarter Moon sunset in August, then you’ve likely noticed on its way to superior conjunction (where it th 9 New Moon the striking vista of four bright planets— lines up with the Sun in the sky) on the 20 , and it will be lost in the sun’s light well before 16 First-Quarter Moon Venus, Jupiter, Saturn, and Mars—lined up 24 Full Moon from southwest to southeast. Even without then. a telescope, their sweep makes a memorable Early in the month, Venus appears only view, and the arrangement will continue well 10° above the horizon 30 minutes after sun- In the Observer into September; if you haven’t seen it you set, and as noted above, it will get lower daily. President’s Message . .2 should—get outside about a half-hour after Though this will make telescopic observa- sunset and look for the planets to start com- tions increasingly challenging, the upside is Society Directory. 2 ing out. As the month progresses, Venus will that by mid-month, the planet will also ap- Schedule of Events . 2 pear as a stunning, large and bright crescent, get lower in the west, so you’ll need a clear Front Range Light Pollution . .3 horizon. reaching magnitude -4.6 at its peak, accord- Mercury continues as a pre-dawn object ing to SkySafari software (the folks atSky and About Denver Astronomical Society . 3 in early September, rising about 1½ hours Telescope say -4.8!). Astro Update . 4 The dust storms on Mars are reported before the Sun. Around 5:30 AM, an hour be- DAS News . 5 fore sunup, Mercury sits 4° above the eastern to be abating, but visibility of the planet’s The Observer is available in color PDF format from the DAS Continued on Page 6 website: https://www.denverastro.org/das/?page_id=13 THE DENVER OBSERVER SEPTEMBER 2018 Society Directory PRESIDENT’S MESSAGE by Ron Hranac DAS Executive Board Sometimes, You Don’t Need a Telescope President: Ron Hranac The peak of the annual Perseid meteor or “falling” stars. They’re produced when a [email protected] shower has come and gone, and this year’s meteoroid enters Earth’s atmosphere, becom- Vice President: was by most accounts a pretty good one. The ing visible when it’s 50 to 75 miles or so above Lindsey Shaw [email protected] peak occurred at the same time as our August the surface. Meteor showers occur when Secretary: dark sky weekend. Throw in pleasant summer Earth passes through streams of debris left Ed Ladner weather and a new Moon, and we had nearly behind by comets and perhaps some asteroids. [email protected] ideal observing conditions. Smoke and haze Surprisingly, most meteoroids that produce Treasurer: Scott Perrin from wildfires in the western U.S. notwith- visible meteors are no larger than the size of [email protected] standing, quite a few Denver Astronomical a pea. The American Meteor Society has a Executive Board Members: Past President, Ron Pearson Society members and their guests trekked to calendar of major meteor showers available on July Candia Ed Scholes the Edmund G. Kline Dark Site (http://www. their web site at https://www.amsmeteors.org/ Jack Eastman Sorin denverastro.org/?page_id=85) to observe the meteor-showers/meteor-shower-calendar/. Joe Gafford Chris Ubing Dena McClung Dan Wray show. Estimates I heard from some members Sporadic meteors: These are also pro- about meteor counts ranged from 15-20 per duced when meteoroids (or small asteroids) President Emeritus, Larry Brooks hour to as many as 50 per hour. enter Earth’s atmosphere, but are not associ- Committees Why am I mentioning the Perseid meteor ated with meteor showers. Van Nattan-Hansen Scholarship Fund: Megan Daniels (Chair) shower after the fact? Because meteor showers Observation of meteor showers and spo- [email protected] are among things-astronomical that can be radic meteors is best done away from bright EGK Dark Site Committee: Darrell Dodge, Interim Chair enjoyed without optical aid. (Indeed, trying lights, preferably between about local mid- [email protected] to observe a meteor shower with a telescope night and sunrise. Dress for the weather, apply IDA Representative: would be an exercise in futility.) It’s easy to insect repellant if necessary, grab a reclining Dr. Robert Stencel [email protected] forget that there is much in the sky one can lawn chair, and lie back and look up to get the Volunteers or Appointed enjoy without a ’scope. Here’s a list of some of best view of as much of the sky as possible. Representatives my favorites, in no particular order. Constellations: A fun way to enjoy the ALCor: Meteor showers: Meteors are the visible night sky is to observe the constellations, Darrell Dodge 303 932-1309 streaks of light that are often called “shooting” groups of stars that form familiar patterns (the Newsletter Editor: Zachary Singer 303 718-4188 Continued on Page 5 [email protected] Newsletter Proofreaders: DAS SCHEDULE Darrell Dodge, Ron Hranac Website: September 2018 Darrell Dodge [email protected] 8 Dark Sky Weekend—EGK Dark Site & Brooks Observatory IT Coordinator: Ken Sturrock 15 Open House—DU’s Historic Chamberlin Observatory—Starts at 7:30 PM [email protected] 21 DAS General Meeting—DU’s Olin Hall, Rm. 105—Starts at 7:30 PM External Outreach Coordinator: Julie (July) Candia 28 E-Board Meeting—At DU’s Historic Chamberlin Observatory, 7:30 PM. [email protected] All members welcome. Public Night Coordinator: (October 2018) Hugh Davidson 303 679-0629 6 Dark Sky Weekend—EGK Dark Site & Brooks Observatory Librarian: Eileen Barela 6-14 Okie-Tex Star Party (near Kenton, Oklahoma) Telescope Loan Program: 13 Open House—DU’s Historic Chamberlin Observatory—Starts at 7:30 PM Ed Scholes [email protected] DAS Information Line: (303) 871-5172 During Open House, volunteer members of the DAS Public Nights feature a presentation on astronomical DAS Correspondence: bring their telescopes to the Chamberlin Observa- subjects and a small-group observing session on the Denver Astronomical Society tory’s front (south) lawn, so the public can enjoy historic 20-inch telescope (weather permitting), at Cham- P.O. Box 102738 views of the stars and planets, try out different berlin Observatory on Tuesday and Thursday evenings Denver, Colorado 80250 telescope designs, and get advice from DAS mem- (except holidays), beginning at the following times: [email protected] bers. The Observatory is open, too (costs listed March 10 - September 30 at 8:30 PM New-Member Ambassador: below), and its historic 20-inch telescope is open Digby Kirby for observing with no reservations necessary. October 1 - March 9 at 7:30 PM [email protected] Open House costs (non-members): If the skies are clear, Public Night costs (non-members): $4/adult, (970) 301-2287 $2/person ($5/family), $1/person in inclement weather. $3/child and students with ID. DAS mem- Membership Coordinator: DU students with ID, and DAS members free. bers and DU students with ID: free. Dena McClung [email protected] Members of the public (non-DAS/DU, as above), please make reservations via our website http://www.denverastro.org (www .denverastro .org) or call (303) 871-5172. The Denver Astronomical Society One Mile Nearer the Stars - 2 - ∞ THE DENVER OBSERVER SEPTEMBER 2018 DOES LIGHT POLLUTION HAVE TO by Dr. Bob Stencel HIDE COLORADO SKIES? Light-pollution solutions (LPS) is a ing the night sky. As Jack Eastman, of the residents, rather than code-enforcement phrase that’s been in circulation for a decade Denver Astronomical Society, points out, folk working after hours. Many neighbor- or more, signaling that we don’t have to flat-panel LED lighting could be made less hoods already have (less-than-smart) light- quietly endure increasingly bright skies at harmful with a simple yellow filter overlay ing in place, so persuading a group to invest night. Happily, engineering solutions can to attenuate the blue photons. in lower-impact lights may be a hard sell; produce a win-win result for all (cost-effec- Regionally, there is some encouraging nonetheless, advocating smarter lighting tive lighting without glare and skyglow), if news: Westcliffe, Colorado is an Interna- can pay off over the long run, because these we have the will to pursue them. In spite of tional Dark Sky Association-designated light fixtures will eventually get replaced. that, metro Denver and Colorado’s Front dark-sky-friendly community. You can find 3. When you see a construction fence Range are awash in skyglow. Why? their progress reports at: https://www.darkski- appear, it often has signage, allowing you First, what is skyglow? Arguably, it is the escolorado.org/. Boulder is facing a mandate to contact the owner/builder and to advo- summation of all of the glare and light seen to begin enforcing their lighting codes, and cate for smarter lighting before they invest all around us in metro areas—this glare and will revisit the topic this autumn, according in excessively bright, inferior equipment “light-trespass” result from mis-aimed light. to activist Richard O’Brien. Northern Lara- that adds to glare and skyglow.
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