Looking Up: Bright yellow Capella shines in northwest
Here we are in the height of spring and I am talking about a winter star. One of the several brilliant stars that dominate the winter evening sky keeps on going, and if you live far enough north, it is with you every night of the year. The star is Capella, the yellow beacon in in the northwestern sky of spring evenings.
Capella is rated as magnitude +0.08, and is the sixth brightest star in the night sky. It is fairly close, only 42.9 light years from the Sun. That’s how many years it takes Capella’s light to reach us, traveling at 186,000 miles a second.
Although Capella appears as a single star in a small telescope, it is actually quadruple star system, with two binary pairs. Its two largest stars are each far bigger than the Sun.
It’s the brightest star in the constellation Auriga, the Chariot Driver.
From Hawley, Pa., where this column was written, Capella dips below the northwest horizon for a short time every 24 hours, and rises in the northeast.
Hawley is located just shy of 42 degrees north latitude, measured on the sky from an imaginary point very close to the North Star (Polaris).
The Earth spins around on its axis, an imagined line connecting the South Pole, the center of the Earth and the North Pole, which points at the southern and northern sky.
All of the stars within one’s measure of latitude miss setting below the horizon as the Earth turns every day. As seen from mid-northern latitudes, that includes the constellations Ursa Minor the Little Bear — otherwise known as the Little Dipper, with the North Star at the end of the dipper handle; Ursa Major the Great Bear, containing the Big Dipper; Draco the Dragon; Cepheus the King; his lovely wife Cassiopeia the Queen; and to keep the bears and dragon company, Camelopardalis the Giraffe. The Giraffe is a very dim constellation and requires a good clear, dark night to see it.
North of latitude 44 degrees, Capella is a circumpolar star.
If you travel to upstate New York it is possible to see Capella all night long, although you will need a true, flat northern horizon- without any Adirondack mountains or trees in the way.
The farther north you go, the wider the circumpolar circle on the northern sky. If you stood right on the ice at the North Pole, leaning against the barbershop pole I heard as a child is found there, and looked up during the long winter night, you would soon realize the entire sky above the horizon is circumpolar.
The North Star would be almost exactly straight overhead. Stars on the horizon would not set at all, but would just travel around you. The same of course happens at the South Pole (which, by the way, I don’t think has a barbershop pole).
From back home, when you see Capella low in the northwest, turn to the northeast and find the brilliant blue-white star Vega, just rising and about the same distance from the North Star as Capella.
Due south at around 10 p.m., a crow will be flying by. This crow is the constellation Corpus the Crow. It may not look much like a bird, but it is a nice trapezium of fairly bright stars. This group is to the lower right of a bright bluish star, Spica, the gem of the constellation Virgo.
Very bright and orange, the star Arcturus is prominent high in the southeast in early evening.
Be sure to look high up in the north the next clear evening; the Big Dipper is at its highest, appearing like the "bowl" is turned upside down and the "handle" extending to the right. If you have a low northern horizon, look nearly straight ahead for Cassiopeia, its five prominent stars forming a classic capital W.
During and after dusk, you can see planet Mars, appearing like a reddish star (magnitude +1.7). It is low in the west, to the far lower left of Capella.
Planet Jupiter rises around 10 or 11 p.m., and is highest in the south at around 3 a.m. Jupiter appears like a gloriously bright, white star (magnitude -2.5) but even a small telescope will show its squat disc attended by its four brightest moons. Dark bands can also be glimpsed on Jupiter, using a small telescope and medium to high power.
Full Moon occurs Saturday, May 18.
Keep looking up!
-- Peter Becker is Managing Editor at The News Eagle in Hawley, PA. Notes are welcome at firstname.lastname@example.org. Please mention in what newspaper or web site you read this column.