Milankovitch Cycles Part 1: Orbital Cycles and Earth’s Ice Ages

Milankovitch Cycles Part 1: Orbital Cycles and Earth’s Ice Ages

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.

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Milankovitch Cycles Part 2: Agassiz’s Boulders and Earth’s Orbital Cycles

Milankovitch Cycles Part 2: Agassiz’s Boulders and Earth’s Orbital Cycles

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.

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Milankovitch Cycles Part 4: Adhemar, Le Verrier, and Croll

Milankovitch Cycles Part 4: Adhemar, Le Verrier, and Croll

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.

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Milankovitch Cycles Part 5

Milankovitch Cycles Part 5

By 1920, Milankovtich completed the book he began writing during the World War: Mathematical Theory of Heat Phenomena Produced by Solar Radiation. In this work, Milankovtich set out the mathematical tools he developed by which he calculated and described the amount of solar radiation received planet wide on Mars, Earth and Venus. As mentioned in the introduction to this series of articles, his calculations for Mars and Earth proved accurate. But, because he was unaware of Venus’ dense atmosphere his calculations of Venus’ were not even close — spacecraft probes have measured surface temperatures over 850 degrees Fahrenheit and pressures equal to the pressure 3000 feet underwater. The book received more attention from the public for his Mars’ results than it did from geologists interested in Earth’s Ice Ages because in the first decades of the 20th Century, the popular press was filled with stories about Martians and canals on Mars.

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Milankovitch Cycles Part 6: Impressions

Milankovitch Cycles Part 6: Impressions

The Milankovitch theory identified three aspects of Earth’s orbital motion as causes of the Ice Age glacial periods and the cyclical long term climate change: (1) the changing shape of Earth’s orbit from more circular to more elliptical; (2) cyclical changes in the “tilt” of Earth’s axis of rotation (axial tilt and precession) which affect the amount of solar radiation received by each hemisphere; and (3) the first two aspects acting together to determine where along Earth’s orbit maximum and minimum levels of solar radiation are received. These orbital cycles have always affected Earth’s climate by controlling the amount of solar radiation reaching Earth.

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The Stars Are Free

The Stars Are Free

Once again, I’ve received an email from a member of the public with a heart-rending story. Someone has purchased a star name as a gift to someone they love, or in remembrance of someone who has passed away. They write to me to say they can’t find that star and ask me how to find it. Then once again I am tasked with informing a loving and well-meaning person that they’ve been scammed.

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Farewell Cassini!

Farewell Cassini!

Scientists are wading through a trove of data from Saturn and its moons thanks to the discoveries of the Cassini spacecraft, which was intentionally plunged into Saturn's atmosphere in September. Launched in 1997, Cassini reached the Saturn system in 2004 after gravitationally slingshotting around Venus, Earth, and Jupiter. The spacecraft's 12 instruments collected data that revealed oceans of liquid methane on the surface of Titan, Saturn's largest moon, and helped scientists measure the length of a Saturn day, a long-standing mystery.

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Artwork by RCA Member Beth Kerner. More of Beth's beautiful illustrations can be viewed here.

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What to Do After the Eclipse

What to Do After the Eclipse

The eclipse has come with much fanfare and now it’s over. We’ve invested so much eager anticipation, hard work and excitement into seeing this one that now we’re left wondering what to do next. Here are some ideas:

  1. Process and upload your images. They can go on our Forum, on our Facebook page, in our 2018 calendar and to our Communications Officer, Paul, for use on our website in the future. Also, Dawn is collecting images for a slide show for our September general meeting.

  2. Donate your undamaged solar glasses. At the September meeting, we’ll have a large box to collect used solar glasses. We’ll send them to our friends at Astronomers Without Borders who will donate them to schools and clubs in South American for the 2019 eclipse going over Chile and Argentina.

Image by RCA Member Michael McKeag

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2017 Eclipse Detroit Lake Citizen Science

The eclipse was incredible! At the present, I am still getting the data logged into this short eclipse report.  We rated ourselves in the 95 percentile for statistical efficiency on the performance of the team and the instruments.  Some of the gear was not perfected until two hours before totality! Besides our highly efficient team, we also had a Canadian theorist and European Space Agency and Jodrell Bank Radio Telescope researchers helping us. In all, there were about fourteen people assisting us. All five radio telescopes used performed well at CATE site number three, the LEOS, Hercules II and the ICOM, in the UHF, c band, and s band collected data.

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Our Great American Eclipse Alaska Airlines Flight

Our Great American Eclipse Alaska Airlines Flight

by RCA Member Teela Bright
The day started out early as I woke up around 3:00 am, thinking of my incredible luck in having my name drawn by RCA for such a spectacular event — reviewing in my mind the smiles and amazing support I have had from RCA, knowing in my heart that they would all be with me during this flight, and then some — and knowing I have been blessed with perhaps a once-in-a-lifetime chance to see something so amazing and beautiful.

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Lights Out Portland — Take the Pledge

Lights Out Portland — Take the Pledge

RCA is working together with our friends at Portland Audubon to raise awareness about light pollution. On September 15 turn off your non-essential lights from dusk to dawn, and then to go outside and check out the night sky! Iconic buildings all around Portland will be going lights out to raise awareness about light pollution, including the Fox Tower, the Wells Fargo Tower, OMSI, Bonneville Power Administration, 200 Market, the 911 Federal Building, Montgomery Park, Holladay Park, City of Portland buildings, and 1201 Lloyd! The Lloyd EcoDistrict is cosponsoring the launch event with their own district effort: LightsOut Lloyd PDX.

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Thanks to Our RCA Volunteers at OMSI Total Solar Eclipse Viewing Party, Salem

Thanks to Our RCA Volunteers at OMSI Total Solar Eclipse Viewing Party, Salem

RCA Volunteers shared their time, telescopes and knowledge with over 1,000 people at the OMSI viewing party for the total eclipse in Salem, OR on August 21. Volunteers showed up Saturday afternoon to help set up and many slept overnight in the gravel lot of the Oregon State Fair Grounds to be ready for Monday’s early morning. With 14 wonderful volunteers, there were many activities to engage the attendees of the event. There were 7 telescopes set up for public viewing of the sun and Venus. There was also an eclipse diagram provided by Robin Baker, an RCA astro-photography display and an Oregon roadmap showing path of totality by Paul Salvatore. Lastly, there were activities for kids of all ages that included UV bead bracelets, moon phase wheels, and solar eclipse word searches.

Many thanks to Robin Baker, Paula Frenchen, Yara Green, Bob Hansen (from sister club in Vancouver, BC), Robert Nelson and family, Mario and Maria Pedraza, Marc Singleton, April South, Mike Sutherland, and Do and Uyen Tran for their enthusiasm and generosity on such a spectacular occasion.

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The Joys of a Global Eclipse: British Deaf Astronomical Association

The Joys of a Global Eclipse: British Deaf Astronomical Association

It was billed as the “great American” eclipse, but I’d rather call it the “great global eclipse.” One of my pleasures on Eclipse Day was meeting Graham and Margaret Duhig, members of BDAA, the British Deaf Astronomical Association. I spent the night before the eclipse at a small hotel downtown so I would wake up in the morning close to the train station. When I checked in, I noticed a senior couple signing to each other. The next day as I checked out at 5:15 a.m., the hotel clerk told me I had just missed sharing a taxi with the English astronomers who were here to see the eclipse. When I got to the train station, they were there, so I introduced myself and gave them a card from RCA. They showed me a picture of their group and gave me their contact information. We shared a train ride down and they set up near the capitol steps for the event. There’s more to the story, but I’ll end it by saying I encourage you to visit their website and friend or like them on Facebook.

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We’re All One under the Sun!

We’re All One under the Sun!

I had the pleasure of welcoming the Hardel family (Suzelle, Stephane and their teen daughters, Dilys and Maelle) of Normandy, France to Oregon for the Total Solar Eclipse (TSE). Having little interest in astronomy at the time, they were visiting Spain during the 1999 eclipse that went through France. Like so many members of our club, Suzelle, a member of two Norman astronomy clubs, was lured into astronomy in 2007 when her long-time photography hobby blossomed into astrophotography. By March, when Suzelle was finally granted leave for an extended holiday to the USA, all accommodations along the Path of Totality from Oregon to Idaho were booked. So, she reached out to fellow astronomy clubs in both states asking for advice on accommodation. Having been unexpectedly shut out from OSP, I found myself in the same situation, i.e., all dressed up and nowhere to go. So I immediately extended her an invite to my little house in Portland, while warning her that there could be clouds west of the Cascades.

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Cars on the Observing Field: Lights and A Safety Reminder

Cars on the Observing Field: Lights and A Safety Reminder

Trout Lake Star Party is an annual event that is especially welcome and wonderful, but this year there were a couple of reminders that ultimately, moving cars and expensive telescopes don’t mix well and we need to be careful. Throw in a couple extra accident factors, like people walking around in the dark and cars flashing white light across the field destroying everyone’s night vision and it becomes clear that we need to be cautious as we take our cars out at night.

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We Need Your Help (and Old Photos) for the 2018 Calendar

We Need Your Help (and Old Photos) for the 2018 Calendar

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.

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­Tips for Improving Night Vision

­Tips for Improving Night Vision

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.

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Greater Variety in Telescope Library Due to Demand and Your Donations

Greater Variety in Telescope Library Due to Demand and Your Donations

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.

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Volunteers Needed for Starry Night at the Maryhill Museum

Volunteers Needed for Starry Night at the Maryhill Museum

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!
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