Wednesday, May 23, 2012

Astronomy is Metal: Partial Solar Eclipse

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”…

Friday, May 11, 2012

"Look at all of these... animals!" Meshuggah, Baroness, and Decapitated

The second major concert in two weeks detonated at the HOB Sunset Strip on May 5th, and yours truly had a ringside seat. Meshuggah headlined a bill featuring the newly reinvigorated Decapitated and, unfortunately, Baroness. You can read my formal review of the show here.

As we staggered out of the HOB onto the Strip, wanna be trophy sluts out trolling the Strip for sugar daddies looked upon us in horror whilst exclaiming, "Look at all of these... animals!"

Here's the gist of it!




Due to disillusionment (and work related exhaustion), next up is probably....

Horseback Half Blood

Dave's Underground Laboratory

Wednesday, May 02, 2012

Decibel Magazine Tour: Behemoth, Watain, and The Devil's Blood

An excellent show, you can read my official write up of the tour's April 25th date at the HOB Sunset Strip here. I did not buy any merchandise, but I did manage to take some pretty good pitcures. Here's a sample....

The Devil's Blood





Ufomammut Oro: Opus Primum

Recent columns of Dave's Underground Laboratory here and here.