May 01

What’s Up in the Sky

What’s Up in the Sky – May, 2017

Leo, the “Star” of the Spring Sky

Springtime is great. The trees leaf out, the flowers start to bloom, the songbirds return to their feeders and baths. But the sky does not follow suit. The winter constellations are drifting toward the western horizon and the summer constellations have yet to make their appearance. Except for Leo, that is. Leo, the Lion, stands alone as a beacon hope, guarding his part of the sky so that others dare not trespass. And he’s easy to find.

About forty five minutes after sunset, face south and look about two thirds of the way up from horizon to overhead (your zenith). There you will see a grouping of stars consisting of a backwards question mark (or a sickle) and a right triangle, with the triangle toward the east (left). That’s the constellation Leo, the Lion.

One of the things I like best about Leo is that it is one of those groups of stars that is easy to visualize as the mythological creature it is supposed to represent. Imagine a lion, crouched Sphinx-like on the African grassland, its head and mane facing west, its hind quarters and tail to the east.

Its name is Latin for “lion” and, to the Greeks, represented the Nemean Lion killed by Heracles (Hercules) as one of his twelve labors. It is also one of the earliest recognized constellations, known to ancient Mesopotamians as early as 4000 BCE.

Look first for Regulus, standing alone in this part of the sky. “Regulus”, in Latin, means “little king” and is the name given to it by the astronomer Nicolaus Copernicus in the sixteenth century. It is a fitting name for the “king of the beasts”.

Regulus is a rapidly spinning star some 75 light years distant, much larger and hotter than our Sun. It is also a double star, its companion being visible in a small telescope.

At the other end of the constellation is the star Denebola, whose name comes from the Arabic phrase meaning, “tail of the lion”. It is also more massive than the Sun and has fifteen times the Sun’s luminosity. It is closer than Regulus at a distance of 36 light years.

For those with a small telescope, Leo has much to offer. Just below the bottom-right star of the triangle can be found the “Leo Triplet”, a group of three spiral galaxies all visible at once in the telescope’s field of view. Farther west is another grouping of three bright galaxies also easily visible in a small telescope.

Now it is a great time to enjoy the mild evenings and explore the “king” of the constellations up in the sky.
This month in history:
May 5: Alan Shepard becomes first American in space – 1961
May 11: Launch of first geostationary weather satellite – 1974
May 12: Adler Planetarium in Chicago opens, first planetarium in western hemisphere – 1930
May 20: Pioneer-Venus 1 launched – 1978
May 25: President Kennedy gives speech challenging nation to land astronaut on Moon before the end of the decade – 1961
May 29: First experimental test of Einstein’s General Theory of Relativity performed during total solar eclipse – 1919