My Best Look Ever at the Celestial Western Lunar Limb

How many times have we heard or read that the half Moon is the best time for lunar observing? I know the terminator is most striking at that time, but I really hate that advice. When asked when to best observe the Moon, I answer that it depends what you want to see. Only observing Luna near the half phase limits what can be observed, and I like to explore the entire disk, and when libration allows, sneak peeks of the far side.

On the night of December 6-7, the Moon was 99.8% illuminated when I started observing, but was already past full, so the celestial western limb was starting to show shadows as the Moon began to wane. With the Moon so recently past full, and a libration of over six degrees in latitude, I saw features along the limb that I had never seen before, or at least had never seen well.

I observed over the course of many hours, and watched as features near the terminator disappeared into lunar night. While atmospheric transparency was never great that night, toward the end of the observation it was terrible, and water vapor in the air started turning the images very soft.

The next time you think, "I'm not going to observe tonight because the Moon is full," remember that you might just see part of the lunar surface you've never seen before.

Galilean Moon Observation- November 30, 2014

As usual, I'm late in posting. Thanksgiving weekend was mostly cloudy, but early that Sunday morning was finally clear. I went out to observe the Jovian system from about 4:00 AM until about 6:00 AM.

Observing notes: November 30. 2014

Weather- 3:37 AM CST 51°F- 46°F wind chill
5:17 AM CST Salt Creek Commons 52°F- 46°F wind chill
Wind- South 12 MPH; 24 MPH gusts
Dew point 48°F

Here are Curt Renz's prediction times for Galilean events that morning.

http://www.curtrenz.com/jupiter.html


Just missed Io shadow transit- ended 4:14 AM. Was observing before end of shadow transit, but not looking near limb, where shadows can be hard to detect.

Bad seeing, and got worse.


Watching as Europa separates from Jupiter's disk, after emerging from occultation.

All images are from my Galaxy SIII phone, afocally, and thus the poor quality. Also, Callisto, being so much farther from the Jovian disk was hard to image. I only captured it in a few images, seen below.

Io transit egress- first observed 5:25 AM CST.
Io separation- first observed 5:30 AM CST.

And that wrapped up my first prolonged Jovian observation since late spring.

Sun Pillar, July 5, 2014

I didn't have much time for observing this summer, let alone going through any data and processing for web publishing, so now that I have a little more free time, I'm trying to go back and post some interesting observations from months ago. Bear with me, please.

On July 4, Bill, Javier, and I spent the night observing at Conway Observatory, tracking down the historic close conjunction of asteroids 1 Ceres and 4 Vesta, among other things. As morning twilight brightened the eastern sky, Bill and Javier left. I was finishing closing the observatory, and was also about to leave when I noticed a beam of pinkish-orange light jutting above the horizon, about where the Sun should rise. I stayed at the observatory nearly another hour documenting this rare sight through photos. It could still be seen even after sunrise, and was even visible for awhile when I was driving home. I found it interesting to watch as the intensity and color of the Sun pillar changed over time. Here are some of my photos.

Total Lunar Eclipse from Conway Observatory, October 8, 2014

I started intently watching the sky in August 2007, and truly took up the hobby of astronomy in July 2008, when I bought my 6" Dobsonian. There had been total lunar eclipses in October 2004, and March 2007, and I had seen parts of those, but not through knowledgeable eyes. Since familiarizing myself with the sky, and the science and history of astronomy, there have been four lunar eclipses that totality occurred with the Moon over Northwest Indiana. In February 2008, heavy lake effect snow over Valparaiso prevented me from observing any of the eclipse. That storm was a narrow lake effect band, however, and other parts of the region had clear skies, according to radio reports the next day. Then in December 2010, perhaps the finest lunar eclipse of my lifetime was going to occur, on the winter solstice, and with totality while the Moon was rather high. Again, it snowed. I had planned to observe with Chicago Astronomers at Adler Planetarium, but the snow made driving conditions dangerous, so I stayed home. Not quite a year later, there was another December total lunar eclipse, and while skies were clear at Conway Observatory in Lowell, Indiana, the eclipse started shortly before Moonset, and I could only observe the beginning of the partial phase.

That was the last total lunar eclipse until April 15, 2014, and again, totality would be visible from Northwest Indiana. It should have been a great eclipse to observe. On the 14th, I frequently checked the forecast, and watched satellite images of a large system casting cloud cover over Illinois and Indiana. The system appeared to be moving through, and I was sure would pass before the eclipse began. After midnight, a check of weather websites led me to look out the window, and see bright, glorious moonlight. It was a cold night for mid-April, so I bundled up, went outside, and...

SNOW!!! My friend Ryan, a meteorology student at Valparaiso University had messaged me around that time that a lake effect snow band had pop up unexpectedly, and was dropping snow over much of the region. I was crushed. After waiting so many years for a total lunar eclipse, and being snowed out for February and December eclipses, I really thought snow wouldn't be a problem in the middle of April, but the winter of 2014 was possibly the worst of my life, with far too much snow, too often, and far too many days of dangerously cold temperatures. And of course, another snowstorm in April. Would I ever observe a total lunar eclipse without snow?!?

Fortunately, the wait for the next total eclipse was less than six months. The entire April eclipse would have been seen from Northwest Indiana. While totality for the October 8 eclipse was entirely visible in the region, the Moon would set with most of Luna covered by the Earth's shadow.

http://www.skyandtelescope.com/astronomy-news/observing-news/total-lunar-eclipse-09262014/

Although the Moon wouldn't start to pass through Earth's shadow until the early morning of Wednesday, October 8, for me the experience began the evening before. I was driving to my Tuesday night bowling league, when I noticed Luna above the horizon before I made a left hand turn to the west. The sky was clear, the Sun was about to set, and even the worst forecasts I'd seen had been rather favorable. I stopped at the park across from the bowling alley, ran up the hill, and captured both the Moon rising and the Sun setting. I had a feeling I was finally going to observe a total lunar eclipse before I saw the Sun again.

Sun setting Tuesday, October 7, from Portage, Indiana.

Moon rising Tuesday, October 7, over Portage, Indiana.

Panorama of sunset and moonrise, Tuesday, October 7.

As a third shifter, I usually go to work after I finish bowling, but not that night. Instead, I drove to Conway Observatory. I wouldn't need its rather dark sky to observe the eclipse, but I did want to take advantage of its wide open western horizon, since the eclipse would be ongoing at moonset. Before setting up my telescope, I sat in the heated control room, going over predicted times and graphs in magazines and online. My chance was finally here, and I wanted to be prepared for what I was about to observe. Then I unloaded my equipment, and took images of the Moon while I waited.

Pre-eclipse image of 2014's brightest full Moon.

My telescope was set up not far from the observatory's basement door, and I left a notebook inside, so that I could take little warm up breaks during the night, and record as many moments as possible. The night was chilly, getting down to around 40° F, but with breezy conditions most of the night, it felt colder. I was bundled up, but had forgot to bring gloves, which I would later regret.

Although Calumet Astronomical Society members have access to Conway Observatory any time, it is located on county park property. I didn't arrive until close to midnight, but there was nobody there, and I was kind of surprised. Usually a full Moon, or publicized astronomical events bring gawkers at all hours of the night. Except for howls from coyotes a couple times during the night, everything was quiet at the observatory. Almost too quiet, with no cars driving past, and even the air traffic seemed to be lighter than usual. I hadn't planned to experience my first eclipse alone, but now that the moment had almost come, it was fine by me.

I was working two jobs through the summer and into the fall, and had quite a few days that I was awake for 30 hours or more. This was another long day for me. By the time I was home and climbing in bed, I'd been up for more than 35 hours. The October issue of Sky & Telescope had speculated that the penumbra, Earth's outer shadow, might be visible on the Moon at 3:45 AM CDST. Lacking sleep, I set an alarm on my phone for 3:50, sat down in my chair next to the telescope, and took a ten minute nap.

When I woke up, I immediately sensed that the sky was darker. Earlier, the brightest full Moon of the year cast brilliant light down on the observatory grounds, and the empty farmland surrounding it. I could almost feel that the eclipse was about to begin. When imaging the full disk of the Moon through my Dob my Samsung cell phone, I usually need to use a neutral density filter and turn down the exposure settings to keep the moonlight from overwhelming the camera. Although still bright, and no shadow yet evident on the lunar surface, my camera phone could tell the difference, as the neutral density filter was unnecessary when I took images at 3:53. Just two minutes later I thought the Ocean of Storms on the celestial eastern lunar rim looked darker, and with better contrast than it had earlier. Of course, this would be where Luna was entering Earth's shadow.

Luna entering the penumbral phase. Unlike most of my lunar images, this was taken without a neutral density filter.

By 4:09 AM CDST, it was evident telescopically that the partial eclipse phase had begun, and by 4:11, it was definitely apparent by naked eye. I watched as the shadow reached Mare Humorum at 4:20, and then the crater Copernicus at 4:36. All that time, the sky continued to darken, as Luna received less sunlight to reflect back to me. By 5:00, I could still see my shadow cast by the Moon, but I could also faintly see a hint of the winter Milky Way across the sky.

The lunar limb starts to darken as partial phase begins.

View through the finder scope of my Dobsonian.

I noticed the first hint of red hue on the Moon at 5:10. A few minutes later I could just barely see my shadow on the ground. The Moon was almost totally engulfed by our planet's shadow. As totality set in, I noticed a star off the lunar limb, magnitude 5.7 HD4628. I also found Uranus off the lunar limb in the other direction, at about the same magnitude.

Looking to the western horizon in the distance.

Of course, Jupiter was a nice treat in the east.

When the Earth's shadow started creeping across the Moon, almost everything I knew about lunar imaging no longer applied.

Nearing totality.

Showing red tint. Totality was much darker than I expected.

Magnitude 5.7 star HD 4628 near the lunar limb. I also saw Uranus around this time, though it was too far from the lunar disk for me to image together.

Although the Moon became overall much dimmer than I expected through totality, the northern limb never really went dark. Also during totality, while turning to the east to see the morning twilight starting to break at 5:47, I saw a brief, fast, long Draconid meteor streak north to northeast, down toward that horizon. David Fuller had talked about the Draconid meteor shower in his eclipse video, so I wasn't surprised to see one.

Jupiter and morning twilight in the east.

Clouds to the northeast.

A friend also trying to observe the eclipse from Chesterton reported that clouds had moved in, and sure enough, as the eastern sky continued to brighten, I saw a band of clouds off in that direction. I even watched as a cloud passed over eclipsed Luna at 6:13. I was so excited that I'd finally seen a total lunar eclipse, that I didn't notice when totality ended. Morning twilight was growing ever stronger, and Luna was now low in the western sky.

Totality is over. Seeing conditions deteriorated as the Moon got lower, and dew was starting to become a problem.

Sky & Telescope writer Alan MacRobert had included in his eclipse article an observing phenomenon that I'd never heard of: selenelion. A true selenelion occurs when the totally eclipsed Moon and the Sun are above the horizon together. Totality had ended well before sunrise, but I still thought it would be cool if I could see the partially eclipsed Moon at all after sunrise. It was a close call, and hard to photograph with my phone, but I did indeed see Luna- still partially eclipsed- as the Sun peeked above the horizon, and for a short time after. Then Luna disappeared in the hazy muck near the horizon, and my first total lunar eclipse was over. Success!

Waiting to see if I could catch the partially eclipsed Moon and Sun above the horizon together.

Sunrise before moonset! A partial selenelion! (Or whatever it would be called).

Partially eclipsed Moon still above the horizon after sunrise.

Panorama.

Luna is now lost to the horizon haze.

I shared a few of my images online during the eclipse, and saw some from my friends. Now that the eclipse was over, I went inside the observatory to warm up, and share some details and more images with my friends via the internet. Plus, my hands were freezing. Since I forgot my gloves, and didn't want to waste a moment of eclipse time, I stayed outside as much as possible. Now that it was daylight, I could see three large cracks across my new phone. I took it out of its case because it was easier to get pictures telescopically, but my numb fingers had dropped the phone several times. Oh well. It was worth it. It was worth being cold. It was worth cracking my phone. It was worth missing work. It was worth going too long without sleep. I'd finally observed a total lunar eclipse, and it was all that I'd hoped for. For its rarity and coolness, the Transit of Venus will probably be my favorite observation I'll ever make, but as an experience, I think this eclipse has the Venus transit beat. Now, on to the total solar eclipse of 2017!

Time to go home.