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Contributed / Mike Lynch
We’re getting a great gift in our skies this holiday season with three bright planets — Saturn, Jupiter and Mars — decorating our evening skies. We also have some nice celestial conjunctions, or what I call celestial huggings, between the moon and planets.
Every month there are at least one or two conjunctions. These frequent conjunctions happen because of the ecliptic, the superhighway of the planets in our skies. Planets are wanderers, moving among the stars from night to night and year to year. In fact, the word planet has a Greek origin that 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 in the celestial dome. Early civilizations observed that the moon and the wanderers, or planets, didn’t move randomly among the fixed stars. Instead, they followed about the same path, mainly migrating to the east and at times moving backward, or retrograde, in a westward direction. This path is called the ecliptic because it’s along the same line where eclipses of the sun and moon occur.
All of the planets take pretty much the same ecliptic path among the stars because they, along with our Earth, all orbit the sun in nearly the same geometric plane. They also move along the ecliptic at different speeds. The planets close to the sun, Venus and Mercury, are in the fast lane. Their paths around the sun are shorter and travel faster because the sun has a stronger gravitational pull on them. So they zip around the sun compared to outer planets like Uranus and Neptune, which take their sweet time completing their longer ecliptic circuit. Consider the ecliptic the long and winding road in the stars. Also, along and on either side of the ecliptic are thirteen constellations referred to as zodiac constellations. On any given night or day, a planet or our moon will be in one of these constellations as they travel down the ecliptic highway.
The planets aren’t the only wanderers in the night sky. Human-made satellites rip across the sky in just about all directions. Hundreds of them have been launched into space in the last 70 years. Many of them are still functioning, fulfilling their various missions and tasks, but there’s also a lot of junk up there like dead satellites and spent rocket stages. At my star-watching programs, I’ll inevitably have someone call out, “Hey, look at the satellite up there.”
The best times to spot satellites are early morning and early evening. While the sun has gone down from our point of view on Earth, it’s still shining high up in space where the satellites are. The light we see when we observe satellites is sunlight bouncing off their reflective surfaces.
Some satellites are brighter than others. The absolute king of the satellites is the International Space Station. At first glance it resembles a high-flying jet airliner. There are also the new Elon Musk Starlink communication satellites. Hundreds are already in use, and hundreds more are planned. The only problem is that with so many satellites, astronomical observations from Earth could get messy. I know it affects my astrophotography. Hopefully, solutions can be worked out so this won’t become a huge problem.
There are a lot of good websites and apps for helping you spot and identify satellites. Not only can these help you with satellites, but many apps and websites can also help locate comets, asteroids and more so you can enjoy all the wanderers, natural and human-made!
Celestial Happening this week: The winter solstice is during the afternoon of Wednesday, Dec. 21, and it’s the astronomical first day of winter and the shortest day of the year. From here on, days get longer, and the sun climbs higher and higher in the heavens.
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul and is author of the book, “Stars, a Month by Month Tour of the Constellations” published by Adventure Publications. Send questions to
.
The Rochester Astronomy Club welcomes new members and puts on public star parties. Their website is
rochesterskies.org
.
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