By Mike Lynch
Fourth of July is the season for parades. In the evening sky planets are definitely on parade. Venus, Mars and Saturn are putting on a nice show in the western sky and are assembled in nearly a straight line as they march toward the horizon.
All three of our solar system mates will not only continue their parade nightly through July, but they’ll also be performing some pretty fancy maneuvers.
Planets are certainly wanderers among the stars. In fact the word planet has a Greek origin that’s roughly evolved from what they called wandering stars. Back then no one really knew the nature of the planets except that they appeared to roam among the fixed stars.
Early civilization observed that the moon, as well as the wanderers or planets, certainly didn’t move randomly among the fixed stars, but rather took about the same path among the stars, mostly migrating to the east, but at times retrograding in a westward direction.
They called this path the ecliptic because it was along that path where eclipses of the sun and moon occur.
The reason all the planets and our moon pretty much take the same ecliptic path among the stars is that they all orbit the sun in the nearly the same geometric plane. They also move along the ecliptic at different speeds.
The planets close to the sun, like Venus and Mercury, zip along the ecliptic, orbiting the sun much faster than outer planets like Uranus and Neptune. Along and on either side of the ecliptic are 13 constellations referred to as zodiac constellations.
On any given night or day a planet or the moon will be in one of these as they travel down the ecliptic highway.
That’s why Venus, Mars and Saturn appear to be in such a straight line in the western evening sky. Throughout the month of July, I’ll give you updates on their progress and their conjunctions, or what I call the celestial huggings they have with each other.
Summer evenings are also great for spotting other wanderers in the stars. All the satellites we’ve launched rip across the sky in all directions. And there is a lot of space debris. Early evening and early morning are the best times to spot satellites because while the sun has gone down on Earth, it is still above the horizon in space and bouncing light off the satellites.
The absolute king of the satellites is the International Space Station. At first glance it more closely resembles a high-flying jetliner. It appears even brighter when the space shuttle is docked to it.
There are a lot of good websites for helping you spot and identify satellites, but I think the best one is the Heavens Above at www.heavens-above.com. You can configure it to your location to help you identify satellites or produce rough but still useful star maps.
Mike Lynch is an astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book “Washington Starwatch,” available at bookstores. Check his website, www.lynchandthestars.com.
The Everett Astronomical Society: www.everettastro.org/.