May 15 – 28, 2017

Bird watcher's spring constellation and the Astronomical Magnitude Scale

This year we have brilliant planet Jupiter to guide us to the star Spica and the constellation Corvus the Crow.This year we have brilliant planet Jupiter to guide us to the star Spica and the constellation Corvus the Crow.

When evening twilight deepens, Corvus the Crow takes flight, easily spotted in the south 20 to 30 degrees above the horizon in dark and moderately dark skies. To measure 10 degrees above the skyline, extend an arm at eye level and look out over your closed fist kept hovering above a spot where sky meets land: the top of your fist marks 10 degrees. Climb from that mark once to measure 20 degrees, and so on. Your eyes will meet four stars that shape a pattern that conveys the essence of a bird and the charm of a kite lifted and floating on air.

This spring the proximity of brilliant planet Jupiter, -2.33 magnitude (m), adds to the ease of locating Corvus the Crow, or Raven, whose stars range from 2.56m and 3.00m. Planet Jupiter, the brightest object in the south-southeast, will catch your eye 40 degrees above the horizon even where city lights obscure most stars. Corvus appears below and to the right of Jupiter.

As described on the Astronomical Magnitude Scale, celestial objects with a negative number through 0m are visible with the naked eye even in large cities. Positive magnitudes 1 to 2 are brilliant to bright from dark sky locations, visible in small cities and suburbs and often discernable in large cities. In light polluted locations, designations 3 to 5 may be seen with the aid of binoculars. Refer to http://www.icq.eps.harvard.edu/MagScale.html for more information.

On springtime evenings in the Northern Hemisphere, extend the handle of the Big Dipper to arc to Arcturus, spike Spica and slide into the constellation Corvus the Crow. We sometimes call this extended arc the spring semicircle. (Visible in south-southeast about an hour after sunset in May.)

On springtime evenings in the Northern Hemisphere, extend the handle of the Big Dipper to arc to Arcturus, spike Spica and slide into the constellation Corvus the Crow. We sometimes call this extended arc the spring semicircle. (Visible in south-southeast about an hour after sunset in May.)

Below Jupiter, and directly to the left of the Crow, find Spica (0.96m), the brightest star in the constellation Virgo the Virgin, or Maiden. In spring, Spica and the Crow travel the heavens in tandem all evening. In winter, we find them in morning skies before daybreak.

Bluish Spica and Corvus first climb into view during early April evenings, about a month after the appearance of harbinger of spring star, Arcturus (-0.07m), the second brightest distant sun visible in northeastern skies. Look for brilliant, golden Arcturus above and to the left of Jupiter. Gaze up from Arcturus to spot the Big Dipper and back down again to enjoy the sweep of the curve of the Dipper’s handle stars arcing to Arcturus, speeding to Spica and breezing on to Corvus the Crow.

Judy Isacoff
naturesturn.org

Leave a Reply

Your email address will not be published. Required fields are marked *