A sure sign of spring for stargazers is the sight of the Big Dipper climbing up into the northeastern night sky. You can use the stars of the dipper to find the North Star, a handy skill to have if you are ever lost at night out in the wilderness. Line up the two stars at the top of the bowl of the dipper — Dubhe and Merak are their names if you are trying to impress someone — and point to the north or left this time of year. That will lead you to the North Star or Polaris, which is not a particularly bright star, about the brightness of those in the Big Dipper.
Follow the curve of the handle of the dipper the other way to the bright star Arcturus. An easy way to remember this exercise is “arc to Arcturus.” One of the brightest stars in the sky, you will notice it has an orange color to it. Usually I tell people that we are looking into the past when we are looking at the stars. Arcturus is 37 light years away so that means the light we see left the star 37 years ago. When we are looking at Arcturus, however, we are getting a glimpse of what our sun will look like a few billion years from now. It is swelling up into a red giant star like our sun will in the future. If there was an earth revolving around Arcturus, it would be fried to a crisp by the now-hot star. It is 25 times the size of our sun and putting out about 200 times the heat and energy. Ouch!
A very interesting thing about Arcturus is that it is not sitting still up there. It is tearing across the background of other stars faster than almost any other star. It is moving across the sky at about 1/800th the diameter of the full moon per year. I know that sounds like a snail’s pace, but as far as stars go Arcturus is a champion sprinter. It is also on a whole different trajectory. While the sun and all the other stars we see are on a giant merry-go-round cruising through the cosmos, Arcturus is flying by us at right angles to everything else. Astronomers have found 52 other stars on the same path and one idea is that Arcturus is from another galaxy that fell into our own Milky Way galaxy several billion years ago, a visitor from far, far away.
Arcturus is the brightest star in the constellation Bootes. Look for a kite-shaped grouping of dimmer stars to the north of its brightest star to see the rest of the figure. In mythology, Bootes was the guy that invented the plow. To honor him and his amazing invention, he was placed up in the sky for everyone to see for eternity. My question is, how hard could it have been to invent the plow? It sounds pretty simple to me. What about the guy that invented the iPhone? Why isn’t he up there somewhere?
A little north and east of Arcturus, see if you can spot a small semi-circle of dimmer stars. That grouping is known as Corona Borealis, the Northern Crown. It does not really have anything to do with Bootes, but in mythology, Bacchus, the god of wine and partying, threw that crown up into the sky to impress his new bride Ariadne.
Really big ‘thing’
Be sure to look closely at that little crown because you are looking in the direction of the largest “thing” in the universe. I know that sounds like a preposterous claim, but astronomers tell us it is really there and they call it the Hercules-Corona Borealis Great Wall. An unbelievably big super-structure of billions of galaxies each containing hundreds of billions of stars, the “thing” measures a whopping 10 billion light years across. If you want to convert that to miles, multiply 10 billion by 6 trillion. If you are wondering how big a number a trillion could be, think of it in terms of dollars. A trillion dollars is a stack of 1,000 bills 64 miles high! That is not $1 or $10 or $100 bills, but rather $1,000 bills. The “thing” is so big no one has figured out how it can even exist.
What does this all have to do with us? Probably not a whole lot really. After all, how does an ant relate to Mt. Everest? But if you feel like your ego is too big and you want to feel small again, spend some time gazing up at that little crown. By the way, if you want to check out Arcturus, do not put it off too much longer. It will have zoomed by us and be out of sight in another million years or so.