In the pale blue sky of evening twilight, the crystalline light of Arcturus, -0.07 magnitude, summer’s brightest star, emerges above the forested ridge to the southwest, halfway to zenith. Minutes later, at the top of the sky, just south of zenith, Vega, 0.00m, second brightest summer star, appears. As darkness deepens, Altair, 0.75m, and Deneb, 1.25m, join Vega to complete the Summer Triangle asterism. The smaller the magnitude number the brighter the star.
Motivated as I was to see the stars, I longed to see the familiar little brown bats that come out with the stars. I felt their absence in my recent experience of summer. As if a wish realized, a little brown bat fluttered into view. On pointed, whirring wings, the dark, bird-like flying mammal broadly circled the forested perimeter of my garden, flying over and beyond and returning again, circling and dipping, [https://www.batcon.org/] clearly snapping up insects. I relished my visitor and sensed the recognition was mutual.
To preserve Earth’s nighttime environment and dark skies, [https://darksky.org/] perform small actions to prevent light pollution: be sure to turn off exterior lighting when not needed and pull shades where interior lights are in use.
In a clear, dark sky, see Cygnus the Swan, its tail marked by Deneb at the top of the Summer Triangle in the skyview diagram. Aquila the Eagle soars from Altair and the constellation Lyra the Lyre emanates from Vega.
Enjoy tracing the stars of the arc of the Big Dipper’s handle to “arc to Arcturus”. Then, continuing the arc, “speed to Spica”, 0.96m, before the bright, bluish star sets in the west-southwest around 10:30 p.m.
A few details: New Moon on August 4, when astronomical twilight or maximum darkness, nightfall begins at 10:03 p.m. Day length 14 hours 20 minutes.
The Perseid Meteor Shower, the most anticipated and prolific meteor event of the year, is predicted to peak the night of August 11 into dawn August 12. Best visibility from midnight the 11th through the pre-dawn hours of the morning of the 12th. The Perseid radiant rises in the middle of the night and is highest at dawn. [https://earthsky.org/astronomy-essentials/everything-you-need-to-know-perseid-meteor-shower/] Look again the night of August 12 into dawn the 13th.
On the morning of the Perseid Meteor Shower, August 12, astronomical twilight ends at 4:09 a.m. Civil twilight begins at 5:27 a.m. Sunrise 30 minutes later. Day length 14 hours 1 minute.
“Forecasters are predicting a Perseid outburst this year with double normal rates on the night of Aug. 11-12,” said Bill Cooke with NASA’s Meteoroid Environments Office in Huntsville, Alabama. [https://www.nasa.gov/solar-system/look-up-perseid-meteor-shower-peaks-aug-11-12/]
“Under perfect conditions, rates could soar to 200 meteors per hour.… An outburst is a meteor shower with more meteors than usual. The last Perseid outburst occurred in 2009.” Every Perseid meteor is a bit of the debris field of comet Swift-Tuttle, which orbits the sun every 133 years.
Perseid shooting stars may be observed sporadically from now through the end of August.
Copyright © 2024 Judy Isacoff
