The Moon illuminates a snowy scene (my back yard) in the pre-dawn darkness. This is an 80 second exposure at 35mm f/3.2 and ISO 125. The yellow-gold color on the background trees is from low-pressure sodium streetlights on the next street over. Click on the image to enlarge; right-click to open the full-resolution version in a new tab.
I took these from up on the catwalk of the U.S. Naval Observatory Flagstaff Station‘s 61-inch astrometric telescope in Flagstaff, on the evening of 2018-04-17. In all, I got 43 decent exposures, from which I picked four that I liked and that spanned the range of useful twilight brightness. All times are MST. Camera: Canon G3 X.
Images ©Marc A. Murison, CC BY-NC-ND.
Click on an image to enlarge; right-click to view at full resolution in a separate browser tab.
This first image was fairly early, when the Sun was just 6.8 degrees below the horizon (just past the end of civil twilight) and the twilight sky was still bright. Visually, you could just discriminate the reflected Earth light on the dark part of the Moon’s disk from the twilight sky background.
This next exposure was when the Sun was 8.8 degrees below the horizon, about halfway through nautical twilight. Right around this time, the lighting was at its most ethereal and, I think, beautiful. It was a wondrous sight.
This next one is a closeup of just the Moon, showing reflected Earth light from the non-sunlit part of the Moon’s disk. Reflected Earth light is visually striking when the Moon is a thin crescent — look for it the next time you see a thin crescent Moon. The faint arc to the left of the Moon is an internal camera lens reflection from the bright, sunlit sliver. The star on the left is 5 Tau, magnitude 4.1. The fainter one below-left is HD 21379, magnitude 6.25. The stars appear as short trails, and the features of the Moon are blurred, due to the Earth’s rotation during the 2 seconds that the camera shutter was open.
This final image shows the sky when the Sun was 11.8 degrees below the horizon — just before the end of nautical twilight and the beginning of astronomical twilight. The end of astronomical twilight, when the Sun is 18 degrees below the horizon, is when the sky is typically dark enough for astronomers to begin observing. Although you can still see a faint twilight glow near the western horizon even at the end of astronomical twilight, the sky is bright enough to interfere with observations only close to the horizon — where we almost never point telescopes anyway. (The usual rule-of-thumb limit is 30 degrees above the horizon. Lower than that, and you’re looking through too much of the Earth’s turbulent atmosphere for most types of observations to be scientifically useful.)
A companion collection, Signs of the Flagstaff March for Science, is here.
Now, hey you, mister, can’t you read? You’ve got to have a shirt and tie to get a seat You can’t even watch, no you can’t eat You ain’t supposed to be here The sign said you got to have a membership card to get inside Ugh! Sign, sign, everywhere a sign Blockin’ out the …
Star guts. Ground mountains. Seething motion unseen. Organism detritus. Feculence. Bug poop.
Knees pop as I bend down and pinch a gram of soil between my fingers. I bring it up to my face: grains, and the filler between the grains. I am looking at 1013 bacteria, each a tiny furnace eating chemical energy.
nutrients: carbon, nitrogen, phosphorous, potassium, calcium, magnesium, sunlight.
The critter universe in this quarter of a thimble of soil is more numerous than the stars swirling around the spiral galaxy we call home. By a factor of roughly a hundred. Or 1,500 times more numerous than the people on Earth. I work with such numbers every day. After thirty years, I still cannot fathom their import. Grains escape my clumsy dermal trap and sift back down, to the ground.
soil: earth, terra, qaḏāra, drytt. (The word dirt , from Middle English drytt, annoys soil scientists; it is an epithet.) Clay, silt, sand. Browns and tans, flecks of blacks and reds and whites. Crystalline facets sparkling in bright sunlight.
Soil is Earth’s largest reservoir of carbon, the basis of all known life. Too much carbon in the air, and we die, we voracious eaters and stirrers of dirt. Too little, and we die, we profligate disturbers of Nature. We live, we stumble, we contemplate, among a balance of energies that flow in overlapping cycles, large and small, short and long—a balance that seems ever more fickle, precarious, as the world grows warmer.
I look up and squint. The Sun, a middling, middle-aged star in an unremarkable part of the galaxy, warms my face, the skin on my arms. I know this sensation to be my brain, some still poorly understood interconnected agglomeration of neurons, synapses, and neurotransmitters, making sense (or such is my perceived reality) of neurochemical signals instigated by infrared quanta, packets of energy that were born of violent subatomic interactions and that fled the core of our star a thousand millennia ago. It takes that long for light to wend its random way from the Sun’s core to its surface.
macrofauna: woodlice, worms, beetles, ants.
A roundworm has 300 neurons and several thousand synapses. My cat has three-quarters of a billion neurons, and about 1013 synapses. She is gray and feisty and adorable, and getting on in years, like me, but she is not the sharpest knife in drawer, perhaps also like me. I rub a larger number of bacteria between my fingers than she has synapses, the connections between her brain cells.
mesofauna: mites, nematodes, roundworms, coneheads, blind and heartless pauropods, indestructible tardigrades.
I wonder, where was this microcosm of mineralogy, pinched between my fingers, a million years ago? Flagstaff sits atop the San Francisco Volcanic Field, a complex of around six hundred volcanic cinder cones that have been active over the past six million years. The San Francisco Peaks, named in the 17th century for St. Francis of Assisi, themselves are the weathered remains of a stratovolcano that erupted between 0.4 and 1 million years ago. This bit of soil, at least its silica grains, may very well have been in the upper mantle, squeezing towards a volcanic hole in the Earth’s crust, when the photons warming my skin began their arduous journey.
We know about the bacteria in this pinch of soil, at least their rough numbers if surprisingly little else, because our optical instruments, microscopes, allow us that determination, given enough time and persistence.
microfauna: bacteria and fungi, thousands of species, mostly unknown to science; yeast; protozoa with their pseudopods, their flagella, their cilia; disintegrators of organics.
I don’t see stars in the daytime sky, other than our Sun, but I know they, too, are there, each of them a furnace converting matter in their cores to energy. At night, our telescopes show us their rough numbers, given enough time and persistence. Our microscopes also enable us a rough count of our neurons, and our synapses, these tangled little engines of thought. We don’t yet understand consciousness, our self-awareness that causes us to ask questions, stir the soil, and build tools so we can determine these incomprehensible numbers, and to ponder—if not grasp, for that seems a long way off still—their significance.
A 360-degree panorama from the U.S. Naval Observatory 61-inch telescope dome catwalk, stitched together from nine photos. (You’ll notice I caught the catwalk railing in one of the photos. Oops.) This was on 2015-11-06, with a Canon G3 X.
Probably the best way to view (and download) the full-resolution version of this 23,890×2,597 image, which has such an extreme aspect ratio, is to use the Google viewer (use the magnifier): https://goo.gl/RTXJxp. The version below is 1/6 resolution. (After clicking to enlarge, right-click and open in a new tab to view the 1/6-resolution version.)