Moons

March 22, 2019

Lookout Observatory: making lemonade

Dear Friend of Lookout Observatory,

We have had lots of cloudy, rainy weather in northern California lately. This is good for ending the terrible drought we have had here, but it is not good for taking astronomical pictures. We finally got a few clear nights a week ago, but by then the Moon was past first quarter, heading on toward full, and a bright Moon makes it difficult to photograph faint deep sky objects like nebulae and distant galaxies. Since these are my favorite objects, I don’t even try when the bright Moon is ruining the prospects. But in an effort to turn a lemon into lemonade, I decided to try photographing the Moon itself up close, something I haven’t tried for many years.

I used my 8-inch diameter telescope, first at it’s normal f/8 focus, then with a Barlow lens which doubles it’s focal length to f/16. Both these focal lengths are so long (so high a power) that the whole Moon won’t fit into the camera image, so both of my images are of only a portion of the Moon. The phase of the Moon was about 9.6 days past the last new Moon.

The first picture is of the north central section of the Moon. It covers about 1/3 the diameter of the Moon from north to south and about 1/5 of the diameter from east to west. It seemed appropriate to be thinking about the Moon because recently there has been talk about sending people to the moon again, and we are nearing the 50^th anniversary of the first moon landing. The first humans to set foot on the Moon were Neil Armstrong and Buzz Aldrin on the Apollo 11 Mission. They landed on July 20, 1969 and spent about 21 ½ hours on the surface. Unfortunately, I did not photograph that part of the Moon where they landed. However, my first picture does capture the area where David Scott and James Irwin of the Apollo 15 Mission landed. They were on the moon from July 30 to August 2, 1971. This was the 4^th lunar landing and the first with the lunar roving vehicle and a 3-day stay. They landed where the blue dot is inside the blue square.

If you enlarge my image greatly until it gets blurry, you may be able to see a faint white, wiggly line running down and to the left from the blue dot. For a clearer view, look at the next picture, courtesy of NASA and the internet. This picture is of the same area as my blue square, but taken from the Lunar Reconnaissance Orbiter only 80 miles above the Moon. The white circle shows the landing location. That my image can show as much detail as it does, even though my camera is 3,000 times farther away from the Moon than NASA’s camera is a testament to the wonders of today’s imaging technology.

The Apollo 15 Mission landed near that wiggly line deliberately so they could explore it. It is called Hadley Rille, and it is about 1 mile wide and 80 miles long. Though it looks like a river meandering through a valley, lunar rilles like this one are thought to be channels formed by erosion over a collapsed lava tube. The third picture (also courtesy of NASA and the internet) is one taken by astronaut Irwin showing what Hadley Rille looked like from on the ground.

And finally returning to Earth, or rather the Moon as seen from the Earth, we come to my last picture. I took this with the longer focal length of 3250mm, so it is twice the magnification of my first picture, and the camera was turned slightly compared to the first image. It is of Plato, the large dark crater near the left side of the first image. In this last image, the mountains to the right of Plato are the lunar Alps, and to their right is the Alpine Valley. It is about 100 miles long and 6 miles wide at its widest. If you enlarge the image, you can just make out a 1/3-mile-wide rille meandering down the center of the valley floor. Plato itself, 60 miles across, has small craterlets scattered across its otherwise smooth floor. My image barely reveals the 5 largest, the smallest of which is 1 mile across. In high school I got my first large telescope, 8 inches in diameter. I remembering struggling to see a craterlet on Plato’s floor during a brief moment of clear seeing through our turbulent atmosphere. Now, 60 years later, we can snatch those brief moments from literally thousands of images, fix them in a single image, and study it at leisure – while relaxing with a glass of lemonade!

May peace be with you,

Carter

Click on any image to get a closer look

North central section of the Moon

The moon from the Lunar Reconnaissance Orbiter

The moon from the surface

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Plato, the lunar Alps and the Alpine Valley

February 1, 2018

Moons 0

A Super Blue Moon Eclipse for 2018

Dear Friend of Lookout Observatory

Unless you have been living under a rock or trekking across Siberia for the past month, you have probably heard all the media hype about a “lunar trifecta” – a Super Moon, a Blue Moon and a total eclipse of the moon all occurring at the same time – which happened in the early morning of January 31. Perhaps you even looked at it yourself. Since Lookout Observatory is all closed up for the winter, the (sometime) Resident Astronomer had to report on this event from his primary residence in the Bay Area.

All for your viewing pleasure he dutifully dragged himself out of bed at 4AM, drove to the Berkeley Marina, carried his camera and tripod in the dark up a hill covered with ankle-high dew-soaked grass (accidentally stepping in a large shoe-soaking mud puddle on the way), and finally set up where he had a view across San Francisco Bay, where he could photograph the setting partially eclipsed moon over Marin County, right next to Mount Tamalpais. I hope you are appreciative! (Actually, he had a very selfish reason for doing this. He wanted a “matching bookends” image to go with his image of a rising partially eclipsed Super Moon over Canyon de Chelly in Arizona that he took in October of 2015 and sent out to Lookout Observatory fans back then.)

For those of you who weren’t paying attention to all the talk, a “Blue Moon” has nothing to do with it’s color, but today refers to the second full moon in any calendar month. (Originally it had a slightly different meaning, referring to an extra full moon within any 3-month season, but why split hairs?) It occurs approximately once every 3 years. A “Super Moon” is a recently invented term referring to a full moon that occurs when the moon is at the point in its elliptical path around the earth where the moon is closest to the earth. Therefore the full moon looks slightly larger and brighter than it usually does. Astronomers refer to this point of closest approach to the earth in the moon’s orbit as the perigee point. So you can impress your friends when they talk about a Super Moon by saying, as you look down your nose, “Oh, you mean when the full moon is at perigee?” A Super Moon occurs on average a couple of times a year. A total eclipse of the moon occurs whenever the moon in its orbit around the earth passes entirely inside the earth’s shadow cast from the sun. For this to happen the sun, earth and moon have to be very closely lined up. (This is referred to as “syzygy,” another good word to impress your friends.) Because the moon’s orbit is tilted compared to the earth’s orbit around the sun, the moon usually passes above or below the earth’s shadow when it is on the opposite side of the earth from the sun. A total eclipse of the moon occurs on average every 1 or 2 years. A totally eclipsed moon often looks red because the earth’s atmosphere scatters the blue light, but bends (refracts) the red light and directs some of it on to the moon. Of course, the occurrence of all three of these events at once is a fairly rare event.

The first picture was taken near maximum eclipse, when the moon, about 20 degrees above the horizon, was fully within the earth’s shadow, and it has the usual reddish color. A few stars are also visible. (All pictures were taken with a Canon camera with a 200mm telephoto lens.)

The second picture was taken when the moon was about 2 degrees above the horizon. Mount Tam rises to the left. The houses along the shore are about 10 miles away. The fishing boat at lower right makes the moon, still in partial eclipse, look quite large by comparison. The bird ahead of the boat is much closer, since it looks about one quarter the length of the boat! The early morning haze over the water makes the whole view somewhat blurry, and thin clouds briefly covered the moon.

The last picture is a wider view with the peak of Mt. Tam to the left 15 miles away; the half-set, still partly-eclipsed moon to the right; and a half dozen birds (Terns, I think) scattered across the picture. This was just a couple of minutes before sunrise, the end of an adventure.

Keep looking up,

Carter, (sometime) Resident Astronomer,

Lookout Observatory

Near maximum eclipsed moon setting over Marin County

Partially eclipsed moon – Mount Tamalpais rising to the left

Half set & still partially eclipsed

October 11, 2015

Eclipses, Moons 0

Super Moon Eclipse

Dear Friend of Lookout Observatory,

The last full moon, September 27^th, occurred when the moon was very close to the point in its orbit where it is closest to the earth. This made it appear slightly larger than usual, and it has been dubbed a “super moon.” It so happened that at the same time the earth came between it and the sun, casting the earth’s shadow over it, thus creating a lunar eclipse. From the western part of the U.S. The eclipse began before moonrise, so the moon rose already partly eclipsed. The Lookout Observatory (sometime) Resident Astronomer was on vacation at Canyon de Chelly in Arizona at the time, so the attached photos were taken from the White House Overlook, looking across the Canyon. The first photo was taken at dusk as the moon was first rising. The trees below it are about 2 miles away. The second photo was taken about an hour later, after the moon was totally inside the earth’s shadow and relatively high in the sky. Lunar eclipses, unlike solar eclipses, have a very fuzzy, indistinct edge to them because the earth’s atmosphere scatters the sunlight and the shadow isn’t sharp. This eclipse was darker and redder than most. The color and brightness depends largely on the amount of pollution in the earth’s atmosphere. If you missed this eclipse, I’m afraid the next lunar eclipse won’t occur until 2018. Nevertheless,

Keep looking up,

Carter

Technical details: Partial eclipse photo, cropped – 200mm lens, f/5.6, 1/60s, ISO 800, 7:14 PM MDT. Total eclipse photo, cropped – 200mm lens, f/5.6, 1/2s, ISO 1600, 8:16 PM MDT.

Click on any image to get a closer look

Partial eclipse

Total eclipse