On the summer solstice, June 20th, I was out in a canoe on a small pond shortly after sunset, botanizing and birding. The sun sets slowly during the weeks on either side of the solstice; daylight lingers in the sky. It was awhile before dusk, when I began to scan the sky for the brightest celestial objects to appear through Earth’s dimly lit atmosphere.
Whether from a metropolis or wilderness, polluted or pristine skies, sky gazers are turning to the west to see the first light from space, planet Jupiter. Looking like a star, it is roughly halfway to zenith at about 9 o’clock. Slow down: it takes patience for our eyes to tease out the point of gleaming light.
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Jupiter is moving ever
lower in the west. courtesy Sky and Telescope
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As twilight deepens, we pivot counterclockwise, to the south, to find bronze Mars at nearly the same altitude as Jupiter. A few minutes later, Saturn appears east of Mars, to its left. Note that the rusty planet is rising while Jupiter is setting. Mars is visible until about 2:20am and Jupiter sets close to midnight during the final days of June. Each sets an hour earlier by mid-July.
High above Mars find orange Arcturus, the brightest true star in our summer sky. For me on the solstice, it was time to leave the pond before dark and before the Big Dipper appeared above Arcturus. Not long after I beached the canoe, the distant suns that form the curve of the Dipper’s handle could be seen “arcing to Arcturus.” The orange giant star is visible all night, until the wee hours before dawn. The two stars at the far end of the rectangular bowl of the Dipper are known as the Pointers; they point to Polaris, the North Star, which is rather dim compared to Arcturus. Imagine a line between Merak, the lower star, and Dubhe, the upper; extend that line about five lengths to locate Polaris.
On July 4, Earth’s slightly out of round orbit takes us furthest from the sun, known as aphelion (Greek aph’ helion, ‘from the sun’.)
Earth will be closest to the sun, at perihelion (Greek peri-‘around’ + helios ‘sun’) on January 4, 2017.