Now that we’re well into spring you can easily see the Big Dipper at the start of evening, suspended upside down, high above the Pottsville northern horizon. In fact it’s nearly overhead.
If you’re facing north, it looks like the Big Dipper is pouring its celestial magic onto our part of the Earth. According to old-time lore, the overturned Dipper is one of the reasons we get so much rain this time of year. That and some tender loving care will keep lawns green, gardens growing and farm fields productive, along with helping maintain weeds and dandelions.
At my stargazing programs and parties, I always ask the folks how many constellations they can find in the sky. Most of them can point out two or three, but just about everyone can locate the Big Dipper. Actually, the Big Dipper is not a constellation. It’s what astronomers refer to as an asterism, which is defined as an easily recognized pattern of stars in the sky, but is not one of the “official” 88 constellations that can be seen from Earth, as agreed on internationally back in 1930.
The Big Dipper actually makes up the rear and the tail of the constellation Ursa Major, otherwise known as the Big Bear. The four stars that outline the pot section of the Big Dipper also outline the bear’s derriere. The three stars of the handle outline the bear’s stretched out tail. How it got stretched out is a story for another day. The rest of the stars that make up the head and legs of the Big Bear aren’t nearly as bright, but can be spotted fairly easily this time of year, even in areas of moderate light pollution.
Just as the official constellations have mythology and lore associated with them, so does the Big Dipper. In fact, it can be argued that it’s as American as apple pie.
Prior to the settling of America by the Europeans, the stars we know as the Big Dipper weren’t called the Big Dipper. In England, the Big Dipper was known as the Plough. In Germany, those stars were called Charles’s Wagon; in Ireland, King David’s Chariot; and in ancient Egypt, the leg of the Bull.
Several Native American tribes pictured the bowl of the Big Dipper as a giant bear. They imagined the three handle stars as a family chasing the bear, with the father leading the charge, followed by Mom with a frying pan and one of the kids tagging along in the rear.
No one knows for sure how the Big Dipper got its name in America, but there’s reason to believe that African American slaves, prior to the civil war in the 19th century, had a lot to do with it. They drank from dippers made from hollowed gourds. The slaves pictured a bright giant gourd in the northern stars and referred to it as The Drinking Gourd. They associated it with freedom because it’s always in the northern sky, in the direction of where they could experience freedom. Slaves that managed to escape followed that drinking gourd northward to a new life. Eventually the gourd evolved to the present day moniker, The Big Dipper.
Constellations or asterisms in the night sky are mainly just an accidental scattering of stars that appear in the same general direction of space. Physically, the stars have nothing to do with each other. One big exception is the Big Dipper.
Five of the seven stars in that constellation are believed to have formed together in the same nebulae, beginning their stellar life about 200 million years ago as a small cluster that’s been breaking apart ever since.
There are more than 30 other stars in the sky that also used to be part of this same cluster. Dubhe and Alkaid are not part of the cluster, but the rest of the stars in the Big Dipper are. All of these stars are about 80 light-years away, give or take.
There’s a wonderful natural eye test in the Big Dipper, in the form of double stars Mizar and Alcor in the middle of the handle. Mizar is a bright star, but Alcor is much dimmer. If you can see Alcor, your long-range vision is in great shape; if you can’t, maybe it’s time to visit the eye doctor and spruce up your vision.
Alcor and Mizar are sometimes called the horse and rider, with the brighter star Mizar playing the part of the horse and dimmer Alcor as the rider. Looks can be deceiving though.
These two stars are what’s known astronomically as an optical double star; that is, they have no relation at all physically, they just happen to be in the same line of sight. Mizar is 78 light-years away and Alcor is nearly 82 light years distant. By the way just one light year equals about six trillion miles!
Take a look at Alcor and Mizar with even a small telescope, though, and you’ll see that Mizar itself is a double star system. But, high-tech astronomical analysis reveals that Alcor also has a companion star that’s invisible to the naked eye, and that the two stars are a binary system, slowly orbiting around each other. Get this though! Astronomers have also discovered in the last year that Mizar is more than just a binary system. It’s actually a quintuple star system with five stars in a very complicated orbit around each other.
Forget about Mizar and Alcor being the horse and rider, but rather five horses being driven by a pair of riders!
Celestial hugging
this weekend
The waxing gibbous moon on its way to being full passes below the bright constellation Leo the Lion and hugs up to Jupiter. The largest planet in our solar system is by far the brightest star like object shining high in the southwestern sky. Just with a pair of binoculars or a small telescope you can see up to four of Jupiter’s largest moons. Jupiter is presently about 474 million miles away. It’s so big more than 1,200 earths could fit inside of it!!
(Lynch, an amateur astronomer and professional broadcast meteorologist, can be reached at mikewlynch@comcast.net)