President’s Message – Nov 2021

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Everybody should have a good astro-project on the go. My current one concerns the timing of lunar eclipses.

Solar eclipse geography and timing is known with remarkable precision. So much so that people, including many members of our RASC community, are willing to plan long, difficult, and expensive trips to watch them. The timing and location of the earth’s shadow, or umbra, across the Moon during a lunar eclipse is much more variable and poorly understood.

I was delighted to learn that as far back as 1687, Philippe de la Hire published that the Earth’s shadow was larger than could be accounted for by an airless Earth, leading to lunar eclipses that start a few minutes earlier and end a few minutes later than expected. This was important work, because observing the timing of eclipses was, in principle, one way to measure longitude – as long as the expected timing was well established.

Moon on Dallas Road, Oct 8, 2021, by Randy Enkin

The problem arises from the complex nature of the earth’s atmosphere that obscures, diffracts and refracts the sun’s light on its way to the Moon. I first became aware of the role of amateur lunar crater eclipse timing just before the eclipse last May (which was clouded out), and I am certainly keen to try again on the upcoming lunar eclipse, starting around 23:19 PST on Thursday, November 18. If there are clear skies, I’ll be out with my telescope, noting the time to the tenth of a minute that the earth’s umbra darkens (“immersion”) and then departs (“emersion”) from various lunar craters. Sky and Telescope has been compiling these observations since 1956. Herald and Sinnott (2014) have analysed the compilation, extended back to 1842, with an amazing 22 539 observations. Their main conclusion is that the Earth is surrounded by a “notional eclipse-forming layer” that is 87km thick. It is a really surprising result, since even noctilucent clouds don’t show up that high in the atmosphere.

Herald and Sinnott point out that amateur uninstrumented observations provide continuity with the early observations in their compilation and provide insight into the visual response of the human eye. To help with the observations, Thursday- Friday November 18-19, I have annotated a picture of the full moon with the crater timings predicted by Fred Espenak. I hope some of you will join me making these simple but useful observations.

Look Up,
Randy Enkin,

President’s Message – May 2021

Posted by as President's Message

Part of the fun of amateur astronomy is getting caught up in “rabbit holes”. You see something on Facebook, that gets you looking up articles in the popular press, and then into academic publications, and they lead you in a different direction and everything is so fascinating and time just rushes by…

The Moon aligned with Ogden Point breakwater - Randy Enkin photo
The Moon aligned with Ogden Point breakwater – Randy Enkin photo

My current example is looking into the timing of craters on the moon – when they enter and exit the umbra or full shade of the Earth. It was an important way to figure out the time, and therefore one’s longitude, before reliable clocks were made. In the 18th century, astronomers recognized that there is a problem (La Hire, Tabulae Astronomicae, Paris 1707); the earth’s shadow is over 100 km bigger than expected. The anomaly is bigger than can be explained easily with the atmosphere. One would think this is a simple geometric problem that is fully understood, but it is still under study!

Amateur astronomers are helping collect the necessary data. Sky and Telescope publishes predicted times for when the shadow is expected to cross 24 prominent craters, and they request people to email in their observed times. Upcoming May 26, 2021, eclipse online info. Up to 2011, their database includes 22,539 observations by 764 different people. If the sky is clear between 02:52 and 05:48 on Wednesday May 26, I hope to add my name to the list!

The point is, we are a community of interesting and interested people. We set challenges for ourselves. Some are simple; some are very difficult. Get your telescope to track better. Process an image to show more detail. Understand black holes a bit more. Learn another myth of a constellation. And then we get together (virtually, these days) and support each other in these pursuits.

Astronomy Cafe – June 8, 2020

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A new sunspot!

There is a new sunspot on the Sun after three months of being spotless! Both Bill Weir and Joe Carr captured this apparition. More info on for June 6, 2020.

Solar H-Alpha & White Light – June 5/20 – Bill Weir sketches & outreach photos
Sun with Sunspot & clouds – June 6, 2020 – Joe Carr photo

Golden Week of Webinars in Astrophysics 2020

The link for registration is
Note the time is for Chile time zone which is the same as Central Time

Photos from Edmonton

Thanks to Dave Robinson for forwarding these photos.

Moon set over Edmonton by Larry Wood - June 5th about 5am -ISO 100, 300 mm, 1/60 second
Moon set over Edmonton by Larry Wood – June 5th about 5am -ISO 100, 300 mm, 1/60 second
Noctilucent clouds on the morning of June 4th - a follow up to what Alister Ling talked about last week.
Noctilucent clouds on the morning of June 4th – a follow up to what Alister Ling talked about last week.
Alister with one of his patented moonset shots from Friday - the view from Kinnaird Park.
Alister with one of his patented moonset shots from Friday – “The view from Kinnaird Park, birds chirping, geese honking, lilac bushes perfuming the damp coolness. So much to image lately! It will take a while to process the time slice, time-lapse, valley fog time-lapse. How do you like your Mead/Honey Moon? Pale, yellow, peach, amber?”

Undulating fog in the river valley – a time-lapse captured by Alister. The movie really shows the bulk motions that are not visible to the eye. Sped up 100X. Definitely on the meteorology side of things, but the Moon is in the movie at the start!

Masked Men Make Off with VCO Telescope

On June 4th, vigilant lunar astrophotographer Mike Nash captures RASCals in the act as they conduct top secret mission to ship Victoria Centre Observatory scope to a telescope spa in the Los Angeles area.

Two Masked RASCals Surveying Victoria Centre Observatory Scope
RASCals Furtively Stow TPO 16 Inch RC Telescope in Crate.
The Crate Securely Lashed in Getaway Vehicle … Rumoured to Belong to Mike Nash
Crate Last Seen Passing Southbound Through Richmond BC

Venus setting behind the Chiricahua Mountains from Portal, Arizona

On May 28, 2020, I shot a video of the crescent Venus setting behind the Chiricahua Mountains. This was just 6 days before Venus passed between Earth and the Sun (i.e., inferior conjunction). Shot from Bifrost Observatory, 8-inch Meade LX200, Sony A6000. Fred Espenak (Mr. Eclipse)

Planet Venus setting on 2020 May 28 from Fred Espenak on Vimeo.