Almanac: The Planets Align

In first grade my desk happened to be on the edge of the classroom near a bulletin board on which the teacher had tacked up a poster of the solar system. In addition to drawings of the sun and the then-nine planets (this was before Pluto was demoted) there were little inset pictures of what the surfaces of the non-Earth rocky planets (Mercury, Venus, and Mars) might look like. These renderings were mostly imaginary because no spacecraft had yet explored any planets and existing telescopic images, particularly of Venus, amounted to nothing more than fuzzy blobs. I was captivated by those vividly-colored fantasy landscapes, however, and found them much more interesting than the adventures of Dick and Jane. 

In the decades since we’ve all been treated to an astounding array of images from probes, rovers, and orbiters revealing the dazzling complexity and beauty of the planets, including the gas giants Jupiter, Saturn, Uranus, and Neptune. At one time or another, and in one part of the sky or another, I’ve also seen the five planets visible to the naked eye: brilliant Venus always in the evening or morning sky; ruddy Mars; bright Jupiter and (with good binoculars) its four major moons; yellowish Saturn; and even the faint and singularly unimpressive Mercury. But in all my years of sky watching I’d never gotten the sense, looking up, that I was seeing the solar system—it was always just a planet, or maybe two, appearing and disappearing across the seasons.

That changed the other day.

A friend and I got up at 3:30 a.m. because we’d read that all five naked-eye planets could be seen in the pre-dawn sky. Neither of us have good views to the east, so we walked from her house in Hadley to a wide-open field near the river. We were walking west, our backs to the clear, already brightening sky. The air was moist and cool along the dimly-lit dirt road, and we listened to the mingled music of early-rising songbirds. 

At the far-western edge of the field we turned around to look. And there they were: Venus blazing away above the tree line, then, a little way off to the right, Mars and Jupiter, and, farther out, Saturn. Mercury would have been visible if we had been looking out over the ocean or from some high spot with an unobstructed horizon. But between the trees and the rapidly increasing light Mercery was invisible. Still…it was a rare treat. Seeing four planets in one part of the sky is rare enough, but this was even more unusual because they were arranged in the order of their distance from the sun. The last time this happened was in December 2004 and it won’t happen again until August, 2040.

The four planets traced a line called the ecliptic, which is the plane in which the planets orbit the sun. It was relatively easy, therefore, to grasp the idea that we were standing on the surface of our home planet, looking out at the solar system edge-wise, so to speak, the sun on the left, still below the horizon, then the planets lined up, in order, to the right. For the first time I had a vivid sense of being in the solar system, rather than having that ancient sense of being in the center of all of these orbiting points of light. The solar system came to life, in a way. It wasn’t images on a computer screen, or an artist’s rendering attracting my first-grade eyes. It was the real deal, right there, planets gleaming against a blue/black sky.

You’ve still got time to catch this sight for yourself. Each day the apparent position of the planets shifts slightly as both they, and the Earth, speed along their orbits. But they’ll remain in roughly the same spots for the rest of the month. On June 24, the planets will be strung out in a slightly longer line, but Mercury will be much easier to locate. As an added bonus, on that morning, a thin crescent Moon will sit between Venus and Mars—a stand-in for where the Earth would be if you were an alien looking on from outside the solar system. If you want to catch that particular parade, however, I suggest rising even earlier than we did. The summer solstice is June 21, so the sun will be rising even earlier than it did for us. And if you have binoculars, bring them along…you’ll see the colors better and you may even catch a glimpse of some of Jupiter’s moons…that morning I could see only one of the four Galilean moons, the other three were hiding behind the skirt of their mother planet.

Almanac is a regular Indy column of observations, musings, and occasional harangues related to the woods, waters, mountains, and skies of the Pioneer Valley. Please feel free to comment on posts and add your own experiences or observations.