What’s Up in the Sky – July, 2018
Harmony Has Long Been Sought in the Sky
If you are out in the country, the sounds of summer have replaced the silence of winter in the starry skies. Night birds, cicadas, and crickets accompany the “music of the spheres”, which refers to the ancient belief that the stars in their motions made music of a most wonderful harmony. Pythagoras even believed that all existence is governed by the laws of musical harmony. The Greek concept of the “music of the spheres” even influenced the great Renaissance astronomer Johannes Kepler who attempted to explain Copernican planetary motions by using the laws of music. He did not achieve his goal, but on the way he discovered his famous laws of planetary motion.
I sometimes lament the fact that the sun sets so late at this time of year (just before 9:30 p.m. tonight), that it’s difficult to do any serious observing without staying out well past midnight. Although there is truth in that statement, there is also a flip side. The weather should be more cooperative and there will be great things to see even early in the evening. And as the month progresses, the Sun sets earlier so the nights will begin twenty minutes sooner by the end of the month.
July will offer quite the variety of things to observe this year. Let’s start with planets. You’ve probably been watching Venus, the bright evening star that has dominated the western sky at dusk the past couple of months. On the fifteenth of this month she will be joined by a beautiful, thin crescent Moon, so close together that you won’t be able to fit two fingers held at arm’s length between them. This will be the best pairing of the two that I have seen in many years. Look west any time after sunset. In fact, you could use binoculars to see how early you are able to spot the planet.
Venus isn’t the only visible planet this month. Look right below the Moon on the fourteenth for Mercury (use binoculars). Look due south to see Jupiter about a third of the way up from the horizon and brighter than everything except Venus. Farther in the southeast lies Saturn, shining brightly over the constellation Sagittarius, the Teapot. Later Mars will rise in the southeast and begin its summer show when it is at opposition (in the opposite direction as the Sun) on July 26. Being at opposition, the telescopic viewing of the planet will be at its best.
The summer constellations begin to take their places in the sky with promises of sights to come. Look overhead for the Big Dipper and Bootes and further east for the summer triangle. Meanwhile, the southern horizon promises to reveal Scorpio and Sagittarius while Hercules, with its magnificent star cluster, is nearly overhead. In the next few months there will be plenty to see up in the sky. 
This month in history:
July 1: 100 inch mirror arrives at Mt. Wilson Observatory – 1917
July 4: Supernova, whose remnant is known as the Crab Nebula, is witnessed – 1054
July 4: Mars Pathfinder lands on Mars – 1997
July 6: Newton’s book, Principia, is published – 1687
July 9: Voyager 2 flies past Jupiter – 1979
July 20: Humans walk on Moon for the first time – 1969
July 24: First rocket launched from Cape Canaveral – 1950
