An Eagle, a Swan (and a dolphin)
Published 2:30 pm Friday, June 11, 2010
With the approach of summer new constellations appear in the early evening sky replacing those of winter and spring. The last of the winter constellations Gemini- the twins can still be found just after dark in mid-June. Its two bright stars, Castor and Pollux, provide an interesting contrast in color if you are able to catch them in the late twilight sky before they set in the northwest shortly after sunset.
The prominent spring constellation Leo – the lion remains conspicuous until one hour after sunset and currently contains the red planet Mars. Mars is flanked by two other bright planets, Saturn to the east and Venus to the west. Venus is the brightest object in the sky other than the sun and moon and will command your attention at once!
As the evening progresses, summer stars begin to arrive from the east, notably those of Cygnus-the swan, and Aquila-the eagle.
Cygnus is easy to identify as its seven brightest stars are arranged in the shape of a large cross. So evident is this feature that the constellation is often called the Northern Cross. (Its counterpart the Southern Cross is a constellation proper visible from the Southern Hemisphere and not North Carolina.)
Making the bottom of the cross is the binary star Albireo which in a telescope is a very beautiful star with components of blue and gold. These two stars (which appear single to the unaided eye) orbit each other in a manner similar to the way in which the earth orbits the sun.
Just south of Cygnus is Aquila, whose stars are arranged so they resemble a bird with outstretched wings. Since antiquity Aquila has been known as the soaring eagle. One stone-carved representation of it has been found dating back to 1200 B.C.
Cygnus and Aquila fly precisely along the course of the Summer Milky Way, but on opposite sides and in different directions Cygnus toward the south and Aquila toward the north.
The bright star clouds of this particular region of the Milky Way are interrupted in many places by dark patches representing vast regions of interstellar dust and gas which serve to block the light from the more distant background stars. These dark patches were called holes in the heavens by astronomers before they realized that the dark spaces were composed of something rather than nothing.
Just outside the band of the Milky Way to the east of both Cygnus and Aquila is a very small but quaint constellation called Delphinus the dolphin. This configuration of six stars represents the mammal dolphin, not the dolphin fish.
Delphinus, in legend, is the dolphin that carried the Greek poet Arion safely to shore at Tarentum (a seaport in Italy) allowing him to escape from his enemies.
For a last look at the winter stars and a first look at those of summer, including but not limited to Cygnus, Aquila and Delphinus, join the astronomers at FENCE on Saturday, June 12, after sunset. If the weather is clear, I guarantee you wont be disappointed.