(Viewed 1,306 times)

[Centaur]

There will be a partial (nearly total) lunar eclipse during Saturday 2015 APR 04 (early morning in North America). Only folks in western North America and further west will be able to observe the Moon during maximum obscuration by the Earth’s umbra, which I estimate will be 99.5% of the Moon’s diameter at 12:00 UT (07:00 CDT - 05:00 PDT). Some observers further east, including Chicagoland, will be able to see portions of the initial partial phase of the Moon in the Earth’s umbra.

I’ve created a graphical preview with data for seven phases of the eclipse. The perspective and posted lunar altitudes are for San Francisco, but the event times will be essentially the same for all observers on the night side of the world as long as adjustments are made relative to PDT (UT-7).

Link to preview graphic and data: www.CurtRenz.com/moon.html

Unlike other eclipse sources that assume the Earth’s umbra to be perfectly circular, I take into account the oblate shape of the Earth and the resulting elliptical umbra. Belgian eclipse guru Jean Meeus has written eclipse books in association with NASA’s Fred Espenak. They have the upcoming eclipse listed as total. Meeus replied to me, “Yes, I know that the lunar eclipse of April 2015 may be partial if the oblateness of the umbra is taken into account.”

Those able to view the eclipse at its maximum may be want to report their opinion of whether the eclipse appears partial or total. Photos and descriptions of the eclipse would be welcome additions to this thread.

[Paulie pchris00]

Hmmm... It would be interesting to see at maximum eclipse, but I won't be traveling to see it. Even during last October's total lunar eclipse, my first observation of totality, was not very deep in Earth's umbral shadow. The northern limb during that eclipse was very bright, while the rest of the lunar face was much darker than I expected. I hope some of our members further west will observe this eclipse, and share their observations here.

[Chicago Astronomer - Astro Joe]

I'll be working this event as a Adler Planetarium crew member, but with my own gear.

Not gonna be much, but hope to snag some shots before we lose it to the skyline.

[Centaur]

Mar 30, 2015 9:20:40 GMT -6 Chicago Astronomer - Astro Joe said:

I'll be working this event as a Adler Planetarium crew member, but with my own gear.

Not gonna be much, but hope to snag some shots before we lose it to the skyline.

Indeed, Joe, this may not be a great one for Chicagolanders, considering that it will be predawn and the Moon will set prior to maximum obscuration.

A far more convenient lunar eclipse will happen on 2015 SEP 27. It will be a truly total lunar eclipse, and for Chicagolanders the entire eclipse sequence will occur during the evening.

[Centaur]

My iconoclastic defiance of eclipse authorities, due to my dubbing this morning’s eclipse partial rather than total, became the subject of a Sky & Telescope article: Saturday’s Lunar Eclipse: Not Total?

[Paulie pchris00]

Very interesting. It seems there are variables on both sides of the issue to create a gray area (or perhaps coppery red?), puns intended, as to whether this morning's eclipse was partial or total. It's unfortunate that our region was not able to observe the eclipse at its maximum, to contribute to the observational record.

As it was, I was pleasantly surprised by this eclipse. I observed it alone in the cold at Conway Observatory. Unlike last October's total lunar eclipse, my first totality, where I tried to take note of every detail, this morning I enjoyed the eclipse purely for the visual and photographic spectacle. I hope to have my images ready for posting reasonably soon.

I can't wait for the next eclipse in late September.

[Paulie pchris00]

Sky & Telescope included the article linked to above in its July 2015 issue. Congratulations, Curt, for being the first person I know to be mentioned in Sky & Telescope.

However, S&T concludes through data that the Earth's umbra was 4.6 arcseconds beyond the lunar limb at maximum eclipse, making this a total lunar eclipse- barely.

Attachments:

[Centaur]

May 29, 2015 10:55:33 GMT -6 Paulie pchris00 said:

Sky & Telescope included the article linked to above in its July 2015 issue. Congratulations, Curt, for being the first person I know to be mentioned in Sky & Telescope.

However, S&T concludes through data that the Earth's umbra was 4.6 arcseconds beyond the lunar limb at maximum eclipse, making this a total lunar eclipse- barely.

Thank you for the (sort of) compliment, Paulie. However, S&T is not the ultimate authority. Neither are David Herald or Roger Sinnott. It was simply convenient for S&T to assign a task to them in hope of verifying the accuracy of the magazine's prediction of a total eclipse, which had earlier been published with never a hint that a partial eclipse would be possible. Partial eclipses simply don't warrant the hyperbolic headlines beloved by editors. So they excitedly and unquestioningly spread the word about an upcoming total lunar eclipse.

In reality, a supposed extension of 4.6 arcseconds for the diffused umbral edge is ridiculously precise. Even Herald and Sinnott admitted that their conclusion was uncertain, and the article authors placed the word "probably" in front of "just barely total". Eclipse gurus Fred Espenak and Jean Meeus eventually accepted that my prediction of a partial eclipse was likely true.

Actually, there are no ultimate authorities in science. That's the province of theologians. But the people closest to being authorities in this case are the many observers who corroborated my prediction and reported that the eclipse was not quite total; they were mentioned in the S&T article. Empirical evidence trumps mathematical analysis; S&T should have known that.