Can humans see in the dark? The answer is yes and no. Yes, according to a 2013 study, at least 50 percent of the human population may be able to discern the movement of their own hand in absolute darkness. That revelation might help people feel more comfortable in the dark, but most amateur astronomers aren’t trying to see their hand waving in the dark. They are trying to see a faint, fuzzy object in a dimly lit environment. Also, when one is under the stars, there is no absolute darkness. No, we don’t see as well in the dark as many nocturnal animals, but we do see much better in “relative darkness” than most of us imagine.Read More
By the mid-1800s a few scientists were beginning to explore a possible relationship between Earth’s orbital cycles and Earth’s Glacial Epochs and Ice Ages. Their first step was to develop a working model linking Earth’s cyclical orbital changes to corresponding changes in the amount of solar radiation received by earth. Among scientists to begin the exploration before Milutin Milankovitch, three are of special importance for this article: Joseph Adhemar, Urbain Le Verrier and James Croll. In fact, the Milankovitch cycles are sometimes referred to as the Croll-Milankovitch cycles.Read More
We've already started on the 2018 calendar, and we're looking for your help. As is traditional, we are looking for your great astrophotos, so, please keep an eye out for the URL to where you can submit them, which should be available shortly. Also, as this next year is the 30th anniversary of the club, we would also like your help in providing any historical images you might have. If you have photos from the past 30 years of group gatherings, special events, star parties, or even just pictures of club members showing off the stylish fashions of the day, we would be interested to see and possibly use them in the calendar and other publications over the course of next year. For more information contact our Calendar Manager, David Novotny.Read More
Seeking RCA volunteers with telescopes to participate in this event Saturday, July 15, 2017:
Join us at Maryhill for a magical overnight campout and stargazing experience in one of the most majestic settings imaginable. Volunteers from Rose City Astronomers will provide telescopes to give visitors awe-inspiring views of the summer night sky. Catch glimpses of the Milky Way, the Andromeda Galaxy, Sagittarius, and even some meteors if we are lucky!Read More
At our last General meeting, we put one of our 10-inch Dobsonians on the auction block. Although we got no acceptable bids, please take this as a signal of things to come – Some aspects of our collection are going to change soon. Examination of our loans over the past year and more indicate changing demands. We have somewhat fewer loans of those large Dobs, and more demand for other kinds of equipment. Some of the changes are due to increased visibility for the whole collection, but other shifts indicate that our members want to try other kinds of equipment.Read More
We have a busy July coming up. RCA welcomes Leo Cavagnaro from Argentina, past president and founding member of our sister club GAMA (Grupo de Astrónomos Mendocinos Aficionados) arriving today, July 1, to spend the next three months with his friends in the U.S. and Portland. He’ll be joined later by our good friend Carlos Guttierez and the current president of GAMA, Elias Juri. They will all be at the Oregon Star Party and several RCA events. Leo will post announcements regarding their stay on the Forum. Please watch for them and give them a warm Oregon greeting when you see them.Read More
The Telescope Library has become much more active this year, meeting growing demand with an expanding group of volunteers. The number of loans is already over twice that of last years' peak, and demand continues to grow. At this writing, we have 36 reservations, some of which stretch into October. Interest in Astronomy is also rising, due to the Eclipse on August 21, and we have seen the effects of this in some reservations and questions. More about this next month.Read More
This is third in a series by RCA Member David Horne. This installment will complete the discussion of Earth’s orbital cycles. We can then turn to the Milankovich Theory, its origins and predictions.
There are three basic cycles involved in Earth’s orbit around the sun: eccentricity, orbital precession, and orbital inclination.
The morning of July 11, 1991 our family packed up into the car and headed down the road to find a clear spot from which to view one of the longest total eclipses of the sun. It was on a rural road on the big island of Hawaii and fortunately there was little traffic. After fitting everyone with solar viewing glasses and setting up my tripod holding both my still camera and video camera, the partial eclipse was well under way. However, more clouds were starting to move in from the direction of the centerline path of the eclipse. I panicked and with difficulty herded grumpy kids and all back into the car and drove further down the road to get away from the clouds.Read More
Good weather means star parties and with star parties comes the issue of good light management, so it never hurts to review basic field manners. Stargazers do try valiantly to manage their red lights, but LED manufacturers are making their lights brighter and brighter. Given that with modern technology more is always better, we can assume that these lights are going to continue to get even brighter. I did a check for “dimmable red LED flashlight” on Google and came up with these items: Mini Strong Brightness, Energizer Industrial LED, Military Tactical LED, Bulbrite, Brite LED Headlamp... you get the picture. However, a much better choice would be one of the many dimmable astronomical flashlights that are available. We recommend the Rigel Systems Starlight.Read More
For starters, I didn't quite realize how well Horn Rapids Campground is suited for astronomical observing. It's flat, grassy, easy to get to; has water, electricity, bathrooms and huge open areas. The next day the buses arrived on time for our B Reactor Tour, which was most excellent. That night we moved up to LIGO for a star party we had planned with the local astronomy club. That was the night of the stunning aurora display....Read More
For hundreds of years, people in northern and central Europe had been noticing large, out-of-place boulders that seemed to have been dropped in a field, or popped up from underground. “Erratics”, they came to be called. Legends attributed the boulders to giants, trolls, and the Devil. By the early 1820s many natural history philosophers, scientists, came to focus on ‘ice’ as the likely mechanism of transport. But the source of all the ice was a mystery.
This is second in a series by RCA Member David Horne.Read More
In October 2016, I started planning an astro tour to the southern hemisphere. Why Chile? Because Chile is much closer than Australia, plus I am Latino and fluent in Spanish. Of the two main Chile astro destinations, I decided on the Elqui Valley over San Pedro de Atacama for three main reasons. First, the Elqui Valley is easier to reach, one 45 minute flight from Santiago and then a 57km drive to Vicuna. Second, health reasons. San Pedro is situated at 2407 meters (7900 ft); Elqui Valley is lower at 709 meters (2326 ft). Third, the Elqui Valley has 320 clear nights per year (versus 250 for San Pedro).Read More
The more awareness we “shine” on the importance of dark skies, the more we learn of the detrimental effects to biological organisms. Last June, the American Medical Association (AMA) declared that light at night is harmful to our health. Most recently, researchers studying hamsters found that animals can pass the damaging effects of nighttime light exposure to their offspring. We amateur astronomers know the value of dark skies in satisfying our innate sense of wonder, our passion for science, and our psyches’ fondness for the vast silence of space. But how do we appeal to the folks who haven’t caught the astronomy bug?Read More
The Telescope Library has published a call for volunteers. The details can be found in the Telescope Library board on the Forum, and on the Telescope Library page on the RCA Website. Volunteers are needed to make sure service is responsive and can meet demand, maintain the quality and diversity of our collection, and build the library into a resource for the whole group. In exchange, the library offers training and exposure to the various disciplines required for everything the Library will be doing in the future, and the satisfaction of providing good service to the group.Read More
Is it time to start or renew your magazine subscriptions to Astronomy or Sky and Telescope? Be sure to take advantage of the discounts for RCA club members.
Save a stamp by paying at the next RCA meeting. Just drop off your check/cash (and a mailing label or renewal notice from your magazine) at the Magazine Subscription table. We'll help keep these great magazines coming to your mailbox.
If you can't make it to the RCA meetings, see your other options.Read More
This is the story of the imprint of Earth’s orbital cycles on the climate of our planet. Scientists now believe that certain features of Earth’s orbital motions act as a trigger for Earth’s long-term climate cycles, including the cyclical planet-wide glacier cover, popularly called the “Ice Ages” — and termed by science glacial epochs. Scientists first discovered the glacial cycles in the middle of the 19th Century. But the theory linking the glacial epochs to variations in solar radiation caused by cyclical changes in certain of Earth’s orbital motions, had to wait until the first years of the 20th Century.
This is first in a series by RCA Member David Horne.
Please join members and guests of RCA as we March for Science on April 22 in downtown Portland near the waterfront. Why do we march? That’s simple:
We march in support of scientific research, science education, and dark skies.
If that’s not enough reason to march, then:
MARCH TO CELEBRATE EARTH DAY! MARCH TO CELEBRATE INTERNATIONAL DARK SKY WEEK (April 22-28)!
The outreach team is looking for ~10 volunteers to join us at the fairgrounds on 21 August to support OMSI's event in Salem. All 8000 tickets are sold out, so if you wanted to go - here is your chance!If you don't have a scope, we can provide one for you. If you'd rather do some tabling, you can talk to visitors about RCA, eclipse mechanics, go deep into the Sun, Moon, or anything else astro-related you want to speak on. Please note: You may feel free to pause public viewing from your scope as you need in order to take images, and we will suggest people enjoy the sight. OMSI will be encouraging everyone to view the event in silence (for the most part).Read More
Our Telescope Library collection is stored in space donated by OMSI and TMS (where library items are available each month). This year, conditions are changing at OMSI; with construction planned, our collection will have to reside somewhere else. TMS has been very generous with storage, but we are at our limit for space there.Our first choice is acquiring suitable space, to store the collection. Please contact us if you can help with space. Keep in mind that the fair market value of storage space (as rent) is tax-deductible, as are any donations to fund storage space and transportation, due to our non-profit statusRead More