An annular solar eclipse recently occurred throughout the
Pacific region. The eclipse was notable for being the first solar eclipse of
any kind visible in the United States since the annular eclipse of May 10th,
1994. From my vantage point in Los Angeles, the greatest extent of the partial
phase of the eclipse was about 80%, marking the eclipse as the deepest eclipse
that I’ve witnessed since that annular eclipse of 1994, when I positioned
myself in the path of annularity. I’ve also seen, thus far, two total solar
eclipses in my lifetime, both visible from North America, on February 26th
1979 and on July 11th 1991. I’ve seen numerous lunar eclipses over
the years, perhaps about ten in all.
On Saturday, May 6th, numerous moron media
outlets hyped the appearance of the so called “supermoon.” The Moon orbits the
Earth in an ellipse; hence, the Moon’s distance from the Earth varies over the
course of the Moon’s 27-day sidereal period. At one point, the Moon is at
closest approach; this is known as perigee. This occurs with each orbital
cycle, but is more noticeable if the Moon happens to be Full; hence, the so
called “supermoon” as the Moon’s apparent size is large. Approximately two
weeks later, the Moon is furthest from the Earth, a position known as apogee.
Well, apogee occurred on Saturday, May 20th as the Moon was New. By
coincidence, the Moon crossed a node on this day, a position in the Moon’s
orbit where the Moon’s orbital path intersects the ecliptic; therefore, an
eclipse occurred.
When the Moon is at apogee, the Moon’s apparent size is a bit
smaller, about 95% or so, than the Sun’s apparent size. Therefore, the Moon
cannot quite cover up the entire Sun and, instead of a total solar eclipse (the
most spectacular sight one can see in nature, and a truly moving experience),
an annular eclipse occurs. The word “annular” refers to “annulus,” the
mathematical term for ring. In the path of annularity, the Sun appears as a
ring of sunlight around the Moon. Unfortunately, though slightly rarer than a
total solar eclipse, an annular eclipse is not nearly as spectacular as a total
solar eclipse as the Sun is still too bright to directly look at, even in the
path of annularity.
Even so, a very deep partial eclipse, as was visible from
Los Angeles, is not to be missed. A little bit of research reveals a whole host
of phenomena to watch for during a deep partial, aided by the construction of a
few simple, “do it yourself” observing tools. The most formidable tool that I
had in my observing arsenal was an Orion Telescopes 7.17” glass solar filter
specially fitted for my new six-inch Dobsonian telescope from Orion (the third
telescope in my personal armory). The solar filter blocks more than 99.99% of
the Sun’s light. Armed with a 25mm Plössl eyepiece, I was ready to go. However,
even without the aid of a telescope and a filter, pinhole imaging provides a
wonderful means of observing a partial eclipse.
I basically constructed three pinhole imagers, using a
sewing needle to punch a hole in thin tinfoil. The first imager was a Quaker
Oats can, a set up best used for “camera obscura” photography. I also just punched
numerous holes in cardboard, and then covered each hole with tinfoil (each pierced
with a pinhole), to obtain multiple images. Lastly, I also put a slightly larger
hole in tinfoil over one of the tubes of my Alderblick 7x50 binoculars. In
each case, I cast the projected image of the eclipsed Sun onto white foam
board.
May 20th was a typical Spring day along the coast where I live. This means that there’s a good chance of marine layer clouds and light fog, an annoying fact of life right on the coast at specific times of the year. Sure enough, the thin fog was enough to crap out my plans of observing the eclipse with a huge population of my learners on the beach. However, if you go inland a few miles, you’ll quickly get out from under the marine layer. I chose a park in Long Beach as my vantage point, and several learners were still able to join me, my family, and my esteemed colleague Cosmo. Sure enough, it was perfectly clear inland.
The Moon first came in contact with the limb of the Sun
around 5:20pm. Deepest eclipse occurred at 6:38pm, and then the eclipse happens
in reverse until the conclusion, which occurred right at sunset. Besides me, my
family, Cosmo, and the learners, there were several other parties in the park
specifically there to observe the eclipse. Many passersby joined us, as well,
most having no idea that an eclipse was happening.
Besides obviously looking at the partially eclipsed Sun
through the solar filtered telescope and the pinhole imagers, at deepest
eclipse, the light levels of a perfectly clear day were noticeably decreased
due to my vantage point deep within the Moon’s penumbra. Shadows cast by the
asymmetrical Sun during deepest eclipse are also noticeably distorted, with one
side of the shadow sharp and distinct, and the other side fuzzy and softer. A
nice phenomenon to also watch for is pinhole imaging through tree leaves, when
the leaves will act as multiple pinhole imagers, casting projected images of
the partially eclipsed Sun onto a surface. The best opportunity to observe that
phenomenon occurred during deepest eclipse on the wall of the bathrooms at the
park. I took numerous photos through the telescope and of the projections (see below).
The next total solar eclipse visible from North America will
occur on August 21st, 2017. I will position myself in the path of
totality on that morning in eastern Oregon, and I will await the arrival of
totality with my arms raised in supplication…
The Annular Eclipse of May 20th, 2012…
The path of annularity…
The geometry…
Pinhole images….
Binocular projections….
The bathroom wall…
As seen through the filter….
Asymmetrical shadows….
The distorted limb of the Moon against the Sun….
The path of totality on August 21st, 2017…
Bands with the word “eclipse” in their name….
Album titles with the word “eclipse”…
Song titles with the word “eclipse”…
