The Night Sky in Spring
The winter constellations beat a hasty retreat in May due to our lengthening days and the change to Daylight Saving Time. For these reasons also, we must wait a little later for a dark sky, so I'm writing these descriptions for about 10 pm in early May. There are not as many bright stars or obvious constellations as in winter. Telescope owners appreciate this season as the time to go for galaxies, which are extremely faint and distant; however, my focus in this series is on the objects we can see with unaided eyes or binoculars. A sky map is provided below.
Let's begin with a real curiosity. Face south and a bit west. Look up at least three-quarters of the way from horizon to the top of the sky, called the zenith. What's that backward question mark doing up there?
1. Leo. Spring's first harbinger is not the robin, nor the dead skunks, and I can prove it. Back in mid-November, when I was trying to observe the Leonid meteors, I saw Leo the Lion in the east around 3 am. When we talk of spring constellations, we really mean the stars one can see in the civilized dark time of early evening. "All-night" sky watchers are treated to two, maybe three seasons worth of stars, and possibly a rain shower. The question mark frames Leo's neck, shoulder, and foreleg. There is a faint pair to the west which complete the head. The dot on the question mark is bright REG-ulus, and a second bright star is at the tail to the east: De-NEB-ola. We'll use Leo for a reference to find more difficult objects, and we'll use...
2. The Big Dipper. Rivaling Leo for the zenith, the Dipper helps us to find, among other things, north. We spoke of the handle in a previous article. At the other end (west), the pouring end, we have two stars which aim in the general direction of Polaris, the north star.
3. The Little Dipper. As seen from New England, Polaris is about 45 degrees, or halfway, up from the horizon. Its height in the sky depends on your latitude. Sailors depended on it for direction, but as they sailed south along the African coast in the Age of Exploration, they saw Polaris sink lower and lower in the northern sky, until it disappeared altogether. They had reached the equator, and south of that the earth blocked their view of Polaris. There is no South star, so these sailors had to learn some new constellations, and quickly. Polaris is at the end of the Little Dipper's handle, and the rest of the dipper is found to the east, in an orientation the opposite of the Big Dipper's. It's a good, clear night when we can see Little Dip with naked eye.
4. The Gazelle Leaps. The Big Dipper is part of the Great Bear (Ursa Major) constellation, which happens to be upside down if you are facing north. See if you can pull off this contortion act. Face Leo again and bend a little backwards so that the Dipper comes into view. The handle is now a tail, the scoop is the hind quarters, and to the west we see a tapering to a pointy head. So where are the legs? Between the Dipper and Leo is a line of three pairs of stars, which some artists draw as bear paws at the ends of some very long legs. Others refer to this grouping as the tracks left by a leaping gazelle. What do you think?
5. Virgo. This is one of the largest constellations, albeit very nondescript. Virgo rises after Leo, so look east and a little south. Artists have pictured Virgo as a woman, either sitting or lying down. The only bright star is Spica (SPIKE-a), as white as Ivory Snow. If you've found Spica, you've gotten to the bottom of Virgo, so to speak.
6. Berenice's Hair (Coma Berenices). Hair is very hard to see at night, and we need a clear dark sky to see Berenice's. Legend has it that in third century B.C. Egypt, during the reign of Ptolemy III, and at a time when Alexandria was becoming the intellectual capital of the world, Berenice's hair was stolen! She had promised to sacrifice it to her deity, if her husband Ptolemy returned victorious from a campaign in Assyria. He did, she snipped, but one night the hair disappeared. Heads were about to roll when a quick-thinking astronomer pointed to the sky and proclaimed that the hair had been forever enshrined there (look about midway between Spica and the Big Dipper handle for a faint speckling of many stars). The king 'bought it.' (This star group may have inspired angel hair pasta, as well. Mmm!)
7. Bootes (said Boh-ots). Begin at the Big Dipper's arcing handle. Imagine the arc continuing for a handle about three times as long. You should see Arcturus, the fourth brightest star in the sky. I think its champagne color is the nicest of all. The star is located at the base of a long kite-shaped constellation, running south to north. This is Bootes the herdsman. Right now, and forevermore, he is assigned to herd the bear Ursa Major. He does this with the assistance of two guard dogs, Canes Venatici. They are two white stars located between the handle of the Dipper and Berenice's hair. If you are having success finding things so far, and it is a clear, dark night, we can finish with a couple of real challenges.
8. Globular cluster, M3. The big M refers to the eighteenth century astronomer Charles Messier, who catalogued over one hundred sky wonders. These objects are not stars, not comets -- so what are they? They belong to the most interesting class of sky objects i.e. miscellaneous. Using binoculars, look for a fuzzy star between Berenice and the middle of the kite. More obvious in a telescope, the fuzz is a collection of nearly a million stars. Don't worry about the overcrowding though, because this cluster is 200 light years across (in metric, that's about a zillion kilometers).
9. The Whirlpool Galaxy, M51. From the end of the Dipper's handle, slowly drift a little ways toward Berenice, or more accurately, toward the bigger of the two guard dogs of Bootes. Not too far. The dipper star might still be in, or just out of, your binocular view. We are looking for a very, very faint hint of a glowing patch. Galaxies are almost always disappointing sights in all but the biggest of telescopes. If you see one, credit yourself with observing an object that is millions of light years distant. This particular galaxy is a spectacular communicating pair, which means that there is a physical connection, a gravity bridge of stars and dust and gas.
Having difficulties, questions, or just trouble sleeping: simply email me, and I think I can help – with the insomnia, at the least.