When the great orange star, Arcturus, makes its debut in the east around the Spring Equinox, we look through bare trees in the darkness to see the distant sun rise above the horizon. The second brightest star in northern skies – next to Sirius – Arcturus is harbinger of warm weather. Now, as leaves change color in the weeks after the Autumn Equinox, the beacon of summer nights appears low in the west-northwest at dusk, poised to disappear until spring.
To the lower left of Arcturus, close above the southwest horizon, red star Antares, a quintessential summer star, sets less than 2 hours after sunset. As October begins, take the opportunity to bid a fond farewell to Antares, the star at the heart of the constellation Scorpius the Scorpion. On clear nights, Antares is visible from Lower Manhattan. In dark sky locations, catch a fleeting view of the Scorpion reclining on the southwest horizon. Arrive at a dark sky, horizon view before 8 o’clock.
One of the most relatable celestial sequences of early evening is the rhythmic placement of planets Mars, Saturn and Jupiter along a slow arc from Mars, just east of south, to Jupiter in the southwest. Find the string of planets above the figure of the Scorpion. Notice Antares below Saturn and to the left of Jupiter. To the upper right of Jupiter, Arcturus glows. Jupiter sets half an hour before Antares disappears.
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This month, at dusk watch for Mars to appear in the southern sky, Jupiter in the southwest and Saturn roughly midway between.
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Arcturus (from Greek arktos ‘bear’ + ouros guardian), the foot star of the constellation Bootes, the Herdsman, is in close relationship to the Big Dipper. The Dipper is an asterism composed of the brightest stars of the constellation Ursa Major, the Great Bear. A sure way to locate Arcturus is to follow the arc of the Dipper’s handle: simply “arc to Arcturus.”
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In the diagram, see Draco the Dragon between the Big Dipper and the Little Dipper. Notice the lines radiating from the Dragon’s head: this is the apparent radiant of the Draconid meteor shower, which is predicted to peak the evening of Sunday, October 7 and/or Monday, October 8. Visible from dark sky locations, the Draconids, a minor shower, sometimes rewards the sky gazer with many shooting stars. Different from most meteor showers, the peak is not before dawn, rather, begin to observe at nightfall, at around 8pm.
Four constellations mentioned: Scorpius the Scorpion, Draco the Dragon, Ursa Major, Ursa Minor. Two asterisms: the Big Dipper, Little Dipper. Two summer stars: Arcturus, Antares. Three planets: Mars, Saturn, Jupiter. One meteor shower: the Draconids.
Resources
H. A. Rey, Find the Constellations, Second Edition, Houghton Mifflin Harcourt Company, NY 2008. Page 4