Tuesday-Wednesday was almost one of my worst nights at a telescope. It wasn’t because of mud; the sand had absorbed the recent deluges and the only puddles were in the ruts of the dirt road. And the atmosphere above my camp in the San Rafael Swell was clear and still, great for astronomy (though filled with no-see-’ems and mosquitoes hatched from the puddles). No, the problems happened because I had misaligned the ‘scope during setup. I spent most of the night, one of the shortest of the year, trying to figure out what was wrong.
I discovered the cause after I had napped at dawn. In the daylight the mistake popped out — I could have slapped my forehead and exclaimed “D’oh!”
But it’s always good to be outdoors on a clear, moonless night. The southern Milky Way looked like the base of a gigantic overpass. Even with a cranky telescope, I hopped around to some of the more spectacular scenery: the gauzy curtains and sinuous dark “river” of the Lagoon Nebula, the bright open star cluster M21, my favorite globular cluster M22, and shimmering Vega. Before I quit, Venus rose – so close to the brightening dawn that I didn’t dare aim in that direction for fear of bumping the telescope and allowing the sunrise to blast through and fry an eyeball.
The loveliest view had presented itself earlier that morning: King Jupiter and the quartet of his most important courtiers. The grand planet blazed through, then over, a thick Juniper tree. Seen telescopically shortly before 4 a.m., the four big moons were lined up on either side, three to the left while the fourth was far off to the right of Jupiter.
From 3:52 until 4:13 a.m. I shot photos. The moon that was most distant from the planet was too far away, like a grandmom at a picnic who refuses to bunch up with the rest of the family for a photo.
My CCD camera is designed to absorb light streaming in from faint, distant objects like galaxies millions of light-years away. It grabs all the photons it can as fast as it can. When it’s focused on something as brilliant as Jupiter, the subject saturates almost instantly. I experimented, hoping to get a good picture.
Coming onto the computer, they seemed to be of two qualities: just awful and not as terrible. I shot tricolor, three exposures per view, and because the telescope wasn’t aligned right and I had not put on my guide scope, the exposures did not merge. Each view had three overlapping Jupiters in three colors and three sets of moons in red, green and blue. I have software that would allow me to disassemble each into the constituent colors and put images together again, but I didn’t have time to do it then.
I was bummed while driving home. Later, when I disassembled and reassembled the pictures, I found one that was all right. My mood lightened and I thought of the nice views I had seen.
My most successful shots were the last sets, images exposed at 0.003 of a second each. When red, blue and green views are processed and combined to make a color image, the combined exposure is just under one-one hundredth of a second.
It’s hard to capture details on Jupiter in a photo that shows the moons because the giant is much brighter than his subjects. Usually you get either a bloated, blown-out, flat white orb of an overexposed planet with recognizable moons, or you get Jupiter with cloud bands and other details but no moons because they are underexposed, disappearing into black space. Some photographers have “burned in” Jupiter to show details otherwise invisible in a longer exposure while doing nothing to the moons, so that the moons show up too. I don’t like that type of manipulation. Luckily, I was able to bring out planetary features and moons without treating any part of the picture differently from the rest.
[Photo of Jupiter and three moons, which I took June 23, 2009, in the San Rafael Swell. You may need to tilt the screen to see the moons. A larger version is HERE.]
It’s not the greatest picture, but I find it almost as delightful as seeing it in person. Strung out in space along the line of Jupiter’s equator are the Galilean moons Europa, Ganymede and Io. The fourth Galilean moon, too far to the right of Jupiter to fit on this photograph, is Callisto.
Europa is covered with water ice, says a NASA website, (CLICK HERET), “and there is strong evidence that it may be covering an ocean or water or slushy ice.” Ganymede, bigger than the planet Mercury (and what was once considered a planet, Pluto), is the largest moon in the solar system. Io is the most volcanic sphere circling the sun; “parts of its surface often change within weeks” because of eruptions, the space agency adds.
“Callisto is extremely heavily cratered, but has surprised scientists by yielding evidence [to] support the existence of its own subsurface ocean, deep enough inside the moon that it does not affect the surface.”
The moons are called Galilean because Galileo Galilei discovered them. That was in 1610, and he studied them carefully over time, charting their orbits. In that era, official dogma held that all creation centered on Earth. Sun, moon, stars and planets glided around the center. It was heresy to teach otherwise.
But obviously these moons weren’t circling Earth; they were going around another planet. Galileo realized that since moons orbit Jupiter, the Earth might orbit the sun — a severe blow to the Earth-centric view.
Jupiter’s moons have never faded as one of the great attractions of the night sky. They are visible with ordinary binoculars.
How wonderful that astronomy helped overcome the iron grasp of medieval superstition, and how beautiful these remote places are. That night began as one of my worst astronomical excursions, but in retrospect it was saved by the natural beauty above.