Three planets to see this fall
By John Gallup
TN Science Contributor
On our rare clear evenings there will be three planets to observe in the night sky in Girdwood, or anyplace else you might be. One you kind of must hunt for, one that is unquestionably a planet, and towards morning one you almost need sunglasses for!
The one you must know where to look is Saturn. It will have already risen when it gets dark and will be in the southern sky above the Kenai mountains. It is brighter than any of the stars near it and always looks a little yellow to me. To see any detail, including the rings, you will need to magnify it at least 40 times. A good spotting scope might do it, but a telescope is better.
No other object in the night sky stops you in your tracks quite like Saturn. Twenty years ago, when it was higher in the night sky I used to set my telescope up outside Clark Middle School in the morning before school and get the kids excited to start their day. Kids would step up to the scope and peer in. When their head would stop moving, I could tell they saw it. There were two reactions, either “whoa!” or “that’s fake!” The latter group would often go around to the front of the scope to se if I had a little paper Saturn taped there.
Photo of planets in the evening sky. (Photo courtesy of John Gallup)
Right now, Saturn is slowly working its way back up into the northern skies, having been over the southern skies for the last 14 years or so. It takes 29 years to orbit the Sun, so every year for the next several years the view will get better!
Rising a couple of hours later is Jupiter. Far brighter than the brightest stars, you’ll know it’s a planet! Good binoculars braced against something or held by a tripod will show you some of the 4 large moons, and a spotting scope or telescope will show you all 4. Sometimes you won’t see all four because one or more could be in front of it behind the planet.
In 1609 Galileo propped his hand-made telescope against the side of a window in his home and became the first human to see Jupiter’s moons. As he watched night after night, he saw them change position and rightly deduced that they were orbiting the planet. From this he re-thought the thousand-year-old truth if the Earth-centered solar system. Telling others about it was a mistake which very nearly got him burned at the stake!
(Graphic courtesy of John Gallup)
Finally, on towards morning, the brilliant Venus rises over Mt. Alyeska, doing its best imitation of a jet with all its landing lights on. Called since time immemorial either “the morning star” or “the evening star,” it is the brightest object in the heavens that isn’t the Moon or the Sun.
Because Venus orbits the Sun inside Earth’s orbit, we never see it cross the night sky. It spends several months rising, hovering, then turning around and setting in the morning sky, then a week or two later repeats the act in the evening sky. During each appearance it goes through phases much like the moon.
This precipitates arguments with students: “Oh, that’s the Moon!”
“No, that’s a crescent phase of Venus.”
“But it looks like the Moon!” And on and on.
All these sights will be had by those who sign up for “Stars over Girdwood at FVCS. I go out most clear evenings to introduce kids adults, and even overripe individuals to all this cool stuff!