On the back of a snake

In early spring, a long snake slithers its way across the sky. It rises just before sundown and pops up from the horizon much like the first earthly snakes of spring that rise from holes in the ground after a long winter’s nap.
The snake in the sky takes six hours to climb fully above the horizon. On this snake’s back, a person can find some notable star groups. However, if snakes don’t do it for you, then check out the long trail of planets across the sky.
At dusk, four of the five naked-eye planets are observable. At sundown, Venus shimmers above the sunset, and closer to the horizon, Jupiter appears next. Gaze upward in the sky, Mars will be among the first things to appear overhead. Another way to find Mars after the sky darkens a little is to look east of Leo, which is a backwards question mark.
Saturn rises at 7:50 p.m. this week. At 8:30 p.m., it is viewable after clearing the trees or housetops. There will be three bright objects: Arcturus, Spica, and Saturn. Saturn is the one in the middle.
Time to go snake hunting. Hydra is the largest of the constellations, and maybe the dimmest of the 34 original star groups. It dates back to the time of Eratosthenes but surprisingly, it only has one star with an Arabic name. Alphard is the brightest star of the group.
For a how-to-guide that will help stargazers find hydra, we have to return to the question mark. Draw a line from the front two stars of the question mark toward the south. Find a small cluster of dim stars that resemble home plate of a baseball field. This is Hydra’s head. Tracing the line of stars that form Hydra among the stars is difficult. Therefore, after finding its head, finish the way to the tail using a sky map for reference.
As you scope out the body of the snake, stop at the bright star, Alphard. Look right above it at a dim triangle. These stars outline Sextans the Sextant.
Two accounts tell about its creations. This is my favorite one: After the death of Johannes Hevelius, his wife named the group to honor her husband because the Sextant was the tool he used most while making one of history’s most accurate star maps. The other reason is Hevelius himself named it after he lost his favorite sextant in a house fire. Yes, the second one is a boring reason for a constellation, which is why it is said that some modern star groups were named more for zeal than for taste.
Midway along the top of the snake, two ancient constellations are waiting for discovery. The first one is Crater, the cupbearer. Its outline is a simple semi-circle of stars. The second one is Corvus the Crow. This set of stars makes a slight misshapen square.
These three groups combine into one yarn of why all are in the sky. Apollo sent Corvus to fetch some water from
Corvus grabbed Hydra with his claws and flew back to Apollo, where he proclaimed the snake held him up from a speedy return. This outraged Apollo; consequently, he placed the trio in the sky for a lesson.
Look online at www.museumplanetarium.org to find a sky map that will aid in your search for these sky objects and the lesson that mythologists hoped to teach with the telling of this myth. It will be on a map.
Mark Jankowski is director of  Ingram Planetarium. Reach him at mark@ingramplanetarium.org or by calling 575-0033.