When Lion And Bear Stalk The Western Sky

Two beasts walk down the western sky side by side on June evenings at twilight’s end: Ursa Major, the brightest part of which forms the Big Dipper, and Leo the Lion. Stellarium

I’m not a golfer, but golf courses make great places to do astronomy. On a recent windy night, I set up a telescope along the east end of a golf course in Ely, Minn. to share the sights with a group of night sky enthusiasts. We looked at the rising moon, Jupiter, the space station and Saturn, then stepped back to admire Leo and the Big Dipper in the western sky.

Looking at these two bright star groups, it struck me how naturally they amble down the western sky together. Both are easy, bright constellations visible from suburban areas. Just about everyone knows the Big Dipper, but now that the moon’s departing the sky, the return of darkness makes this an ideal time to trace out the massive though fainter bear.

Hydra’s coils are beautifully illustrated in Urania’s Mirror, a star atlas made in 1825. Hydra covers the most area of any of the 88 constellations. It’s best visible in early spring.

And I do mean massive. Ursa Major is third largest of the 88 constellations. Leo’s 12th, and the largest is Hydra the Water Snake. To find the bear, start with the handle, which now becomes his unusually long tail. The top of the bowl is the bear’s back and the bottom of the bowl, his belly. Two legs dangle below the belly, each tipped with a pair of claws. From bowl to claws is 20° or two fists held at arm’s length.

A fist and a half (15°) to the lower right of the bowl, three stars outline Ursa’s head. Taken together, it’s not a bad likeness of a bear if all you have to work with are one dimensional dots and imaginary lines. The same can be said for the sauntering lion to the left of the bear. Shoot a line from the bear’s underside to the left and down, and you’ll run right into Leo’s brightest star, Regulus.

Regulus is four times larger than the sun and rotates so fast — once every 15.7 hours — that it’s squeezed into a shape resembling an egg. The sun rotates much more slowly. about once every 4 weeks. Credit: adapted from and based on a model by Wenjin Huang. Shape of Regulus is approximate.

Regulus lies at the bottom of a backwards question mark that’s actually the head of the lion. If you now connect the head with the flattened triangle of stars representing his haunches and tail, the stellar king of the beasts stands before you. From head to tail, Leo spans 2.5 fists or 25°.

The fate of any constellation that turns up in the western sky at nightfall is sealed. It will gradually sink toward the western horizon and out of view, “pushed” by Earth’s revolution around the sun. Leo will be with us through mid-July before disappearing into the twilight glow, the Big Dipper longer. If you live at 40° N latitude or farther north, the Dipper never sets because it’s not far from the sky’s pivot point, the North Star. But from southern Arizona, the bear sets for a time before coming back to view in the northeastern sky.

Star come, go and come back again, as much a part of the seasons as buttercups and blizzards.