So far in our spring sky we have looked at Orion’s departure, how to rain water down on Leo, how to “arc to Arcturus and speed on to Spica,” how to view Virgo as a further guide to finding Leo (by imagining as though she wants to give Leo a hug). Today we’ll continue our journey in the spring sky with Cancer the Crab, Corvus the Crow, Crater the Cup, and Hydra the Water Serpent. (For the previous spring stargazing posts, see Mid-April Stargazing 2012 and Orion Is Leaving Us!) Below is a map of this spring sky with constellation lines and labels; on the bottom of this post is a spring sky map with constellation figures and a Starhopper’s Guide to help you find and visualize these constellations.
Cancer is easy to place, if not so easy to see. Cancer’s stars are pretty dim, but if you can see them (best get out to the dark countryside and away from city lights), they may look like an X or Y shape to you with a fuzzy splotch in the middle somewhere. To find Cancer, first find Leo. Then look to the right of Leo, because Leo is “looking at” Cancer. That’s about all the helpful tips I have for you there. Cancer is worth finding for that fuzzy splotch, which is the Beehive Cluster (M44, NGC 2632, or Cr 189). M44 is one of the nearest open star clusters to the Solar System. Under dark skies the Beehive Cluster looks like a nebulous object to the naked eye. It is best seen in spring evenings (say, from February to May), and fits well in the field of view of a pair of binoculars or a low-powered telescope.
Corvus, Crater, and Hydra
Beneath Leo and Virgo are three constellations connected by proximity and mythology: Corvus, Crater, and Hydra. (Sextans is in the neighborhood, too, but it’s not part of the story, so I’m going to ignore it in this post.) From my northern mid-latitude location, these three are low in the south. Hydra stretches out long and windingly with Corvus and Crater balanced on top, Corvus positioned towards the left end and Crater to the right of Corvus and near the middle of the snake. The right side of Hydra terminates in a small circlet underneath Cancer, for its head. The tail-end star of Hydra can be found by continuing the “arc to Arcturus, speed on to Spica” trick…I suppose you could “high-tail it on to Hydra’s tail.” Hydra really does look like a serpent; Crater sort of looks like a chalice; and Corvus looks like a skewed square. How do you get a crow out of that? I guess you’ll just have to think of him as a “squarecrow.” Ha! (Caw?)
Anyway, it’s storytime: Once upon a time, Corvus was a beautiful silver-white bird and had a singing voice to match. He was a companion to the god Apollo, who one day sent Corvus off to fetch him some water in his cup (Crater). Corvus took flight with Crater in order to complete this duty; however, along the way Corvus noticed a fig tree full of tantalizing fruit. Corvus loved figs, but these fruits were not quite ripe enough yet. Corvus decided to wait for the figs to ripen so he could eat his fill before returning to Apollo with the water. In fact, in his greed for figs, he had already forgotten about Apollo and the water.
When the figs had finally ripened, Corvus feasted until he was too full to eat more. And then he remembered his duty. He knew he couldn’t return after such a long delay without some excuse, and he had an idea for an excuse when he saw Hydra, the water serpent, by the river. Corvus filled the cup with water and flew straight back to Apollo. He told Apollo that a water serpent was responsible for his tardiness, as the snake prevented him from fetching the water.
Apollo thought this story didn’t hold water–that is to say, he didn’t believe the selfish bird. For his greed, Apollo changed the bird’s beautiful plumage to dirty black. For his lies, Apollo turned the bird’s beautiful song into a raucous caw. Furthermore, Apollo placed Corvus and the cup (Crater) in the sky on the back of Hydra, instructing Hydra to not let Corvus come near enough the cup to drink. (Note: this Hydra is not the multi-headed beast that Hercules fought in his second labor; this Hydra has just one head.)
For your further edification in night sky navigation, here is A Starhopper’s Guide to the South-Facing Spring Sky: