Week of Aug. 26-Sept. 1, 2018
Stargazers who have been out during early evenings over the past month or so may have noticed a stunning sight in our sky, though one that doesn't call great attention to itself. Not long after dusk we can see a beautiful string of planetary pearls, but one of the coolest sights is completely invisible.
Well, sort of. It's only invisible if you don't know how to look.
Stargazers who know something about astronomy can find it on every clear night and morning, but unfortunately, most will not realize its true significance. I'm referring, of course, to the geometric plane of our solar system.
We know that our solar system includes the planets, the sun, the moon, comets, asteroids and tons of other stuff like dust and chunks of ice and rock. Nearly everything in this planetary family orbits the sun in this plane, the result of our planetary system's birth from a rapidly spinning disk billions of years ago.
From within, we can imagine this plane as an arc across our sky; it represents the general paths that the sun, moon and planets take on their journeys through the starry heavens. We call it the ecliptic because it is along this arc that the sun and moon appear to travel, and therefore, it is the only place where eclipses can occur.
The ancients also recognized the ecliptic but of course did not understand its significance. So, they devised 12 stellar groupings to mark its location and knew it as the zodiac among which their gods — the planets, sun and moon — appeared to wander. This week, the zodiacal constellations that appear after dark are, from west to east: Virgo, Libra, Scorpius, Sagittarius and Capricornus.
And this week after dark, sky watchers can trace the ecliptic to find four bright visible planets strung out across the sky!
At dusk, gaze toward the west-southwestern sky and you'll see Venus, the most brilliant planet of our solar system because its Earth-sized globe is quite nearby and shrouded by highly reflective clouds. Farther toward the east appears the Giant Planet, Jupiter, also quite bright and now lying about 500 million miles from us.
Trace a line between these two planets and you've got the beginnings of the ecliptic. Continue the arc eastward and you'll encounter the Ringed Planet, Saturn — spectacular to view through a small telescope — and, finally, the Red Planet, Mars. Mars is particularly bright now because it's as close to us as it's been in 15 years.
Since this arc also represents the general path that the moon takes as it orbits the Earth each month, keep watch very late at night this week as the moon rises in the east and completes the arc in that direction.
Folks who rarely look at the nighttime sky and are uninformed about the workings of our solar system can become quite frightened by this sight. They have occasionally interpreted this configuration as an alignment of the planets — something they believe has important supernatural significance.
I'm not too worried, though. The planets have behaved like this for billions of years. If ever we see them not aligned in this way, then I'll be worried!
Visit Dennis Mammana at dennismammana.com. To read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.
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