As we head deep into spring, you can't help but notice as evening begins you can easily see the Big Dipper standing on its handle and pouring its celestial contents on the Earth.

Old weather and astronomy lore claim the tipping Big Dipper contributes to April showers and May flowers, as well as dandelions.

Believe it or not, the Big Dipper is not officially one of the human-made constellations seen from Earth. It's actually the rear end and tail of the official constellation Ursa Major, otherwise known as the Big Bear. As you can see in the diagram, the Big Dipper is by far the brightest component of the Big Bear. Unless you're viewing the skies from a lit-up shopping mall or some other light polluted area, you should be able to see the rest of the great bear of the heavens.

Ursa Major is one of the biggest constellations in the heavens, and you can really use it to get your bearings in the night sky. It's a great pointer. For example, if you draw a line in your mind's eye from the star Merak to the star Dubhe on the side of the Big Dipper's pot opposite the handle and then continue that line, you'll run right into Polaris, otherwise known as the North Star. Clench your fist and hold it out at arm's length. Three of those fist widths at arm's length is about the distance you have to go from Dubhe to get to Polaris.

The North Star is what I like to call the "Lynch pin" of the heavens. Since Polaris shines almost directly above the Earth's North Pole, every celestial object in the sky appears to revolve around it once every 24 hours, in response to the Earth's rotation below the celestial dome.

The Big Dipper's handle, or the tail of the Big Bear, can also be used as a pointer. In fact, the Big Bear's tail is the first leg of what's called the giant arch of spring, which goes on well beyond Ursa Major and takes you to two of the brightest stars in the spring evening skies.

The middle star in the Big Dipper's handle is a great celestial eye test for you. That star is called Mizar, and if you look very carefully at Mizar with just your naked eyes (eyeglasses count), you'll see it has company.

Just to the lower left of Mizar is a much fainter star, Alcor. Mizar and Alcor are what astronomers call an optical double. Those are double stars that don't have anything to do with each other physically but just happen to lie in the same line of sight from Earth.

Mizar is 78.2 light-years away, and Alcor is 81.2 light-years away. If you're new to this column, a light-year is the distance a beam of light travels in a year's time in the vacuum of space. That's a heck of a long way, with just one light-year equaling nearly six trillion miles!

There are many other fainter double stars in the celestial dome that are gravitationally related to each other. In fact, more than half the stars seen in our sky that appear to be single shiners are actually systems of two, three, or even more stars revolving around each other. A lone star like our sun is the exception rather than the rule.

If you continue along the great arch of spring, beyond the arc of Big Bear's handle, you'll run right into Arcturus, a super bright star and in fact the second brightest nighttime star we see from around here. Just remember the old stargazing saying, "arc to Arcturus."

Arcturus is the brightest star in the spring constellation Bootes the Hunter Farmer. To me and many others, Bootes resembles a giant kite rising on its side in the eastern sky, and Arcturus is at the tail of the kite.

Arcturus is a bloated orange super giant star more than 25 times the diameter of the sun. That would give it a girth of well more than 20 million miles. Even with the naked eye, you can easily see its orange hue. Arcturus is 37 light-years away, making it more than 214 trillion miles from your backyard. Since it's 37 light-years away, the light we see from Arcturus this spring left that bright star 37 years ago in 1973, three years before America's Bicentennial. Nixon was still President.

If you continue the great arch of spring beyond Arcturus, you'll bump into the bright star Spica, which is in the large but faint constellation Virgo the Virgin. Just remember another old stargazing saying, "speed on to Spica."

Spica isn't as large as Arcturus, with a diameter of just less than 5 million miles, but it's a much hotter star, so hot it kicks out 5,000 times more light than our sun. In comparison, Arcturus only emits 1,200 times more light than our sun. Spica doesn't shine as brightly as Arcturus in our sky because it's much farther away in our Milky Way galaxy at a distance of 263 light-years. The light we see from Spica left that giant ball of glowing gas in 1749, about 30 years before the signing of the Declaration of Independence.

Whenever you gaze upon any star, remember you're not only peering out over a tremendous distance, you're also looking back in time.

Enjoy the spring arch and everything available overhead as you stargaze on these much warmer evenings.

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book "Pennsylvania Starwatch," available at bookstores and at his website www.lynchandthestars.com.