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The Sky This Week is a blog that was penned by Geoff Chester, former Public Affairs Officer at the U.S. Naval Observatory. In it, he wrote about observable astronomical phenomenon during the seasons, as well as explanations both historical and scientific of what we see in the sky.

This online archive currently contains 188 entries of The Sky This Week blog, with the earliest article dating from October 27th, 2020 through to his last article posted on October 15th, 2024. You can scroll down to browse entries chronologically from newest to oldest. The table below is also provided to allow for quick navigation to a specific date window:
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September 12, 2023 - November 14, 2023
5
June 27, 2023 - September 5, 2023
6
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12
January 11, 2022 - March 15, 2022
13
October 19, 2021 - December 21, 2021
14
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15
May 18, 2021 - July 27, 2021
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December 23, 2020 - March 2, 2021
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Sitting Under Summer's Stars

by Geoff Chester, USNO Public Affairs | 15 August 2023

by Geoff Chester, USNO Public Affairs | 15 August 2023


The Big Dipper over the Northern Neck, imaged 2023 August 12, from Mollusk, Virginia
with a Canon EOS Rebel SL2 DSLR and an Omegon Mini Trak LX2 mechanical star tracker

The Moon returns to the evening sky late in the week, skirting the southwest horizon as she slides along the southern reaches of the ecliptic.  New Moon occurs on the 16th at 5:38 am Eastern Daylight Time.  If you have a pair of binoculars, use them to help you find Mars just one degree southeast of the Moon about half an hour after sunset on the evening of the 18th.  Luna will “bracket” the bright star Spica on the evenings of the 20th and 21st.

If you missed the peak of the Perseid meteor shower last week, you still have a chance to see some of these swift “shooting stars” over the first few nights of the week.  I was fortunate to have dark skies and a break in the clouds while visiting Virginia’s Northern Neck this past weekend, and was treated to a fine display for an hour before the clouds closed in.  I’m still amazed at how swift the shower members are; you can easily miss one in the blink of an eye.  

The sky in this part of Virginia is quite dark, with the summer Milky Way easily seen in great detail arching overhead.  I spent several hours just staring at the sight, marveling at the brighter stars scattered against the background glow of billions of far more remote luminaries that blended together as an amorphous haze.  The dark rifts that bisect the Galaxy were also easily seen, reminding me of the sky lore of the ancient Inca, who created constellations from these seeming voids.  One of my favorite sights was seeing the stars of the Big Dipper asterism framed between the pine trees as it wheeled around the north celestial pole.  Alcor, the fourth-magnitude star that lies close to Mizar, the star at the bend of the Dipper’s “handle”, was visible.  In ancient times this would have qualified me to serve in the Roman army!  

Overhead, the Summer Triangle can be readily seen from urban skies, but darker sites allow you to trace out the full constellations associated with each of the Triangle’s bright stars.  Deneb, the northernmost and faintest of the Triangle’s stars, marks the “tail” of Cygnus, the Swan, one of the more easily recognized constellations of summer.  Under dark skies the Swan’s neck stretches southwest into one of the densest star clouds of the Milky Way.  The Swan’s “head” is marked by the beautiful double star Albireo, one of the best objects for summer stargazing with a small telescope.  The stars’ components shine with distinctive blue and gold hues that show very nicely in a 3-inch instrument.  Between Deneb and Albireo are the stars that outline the Swan’s wings, giving a fairly decent impression of a swan flying south for the winter.  This is a great area to explore with binoculars, where you will find the bright knots of star clusters sprinkled against a background of uncountable background stars in the Milky Way.

Just to the southeast of the Swan’s neck is a small constellation that stands out in a dark sky.  It consists of a rhombus of four stars with a two star “tail” that points southwest.  This group forms the constellation of Delphinus, the Dolphin, which has been described as a dolphin in Greek and Hindu mythology.  Its two brightest stars have interesting names, Sualocin and Rotanev.  Spell them backwards and you will get Nicolaus Venator, the Latinized name of Niccolo Cacciatore, an astronomer at the Palermo Observatory in Sicily.  The names first appeared in star atlases issued by the Observatory in 1814 in honor of his valued work in compiling a vast (for its day) star catalog.

As mentioned earlier, Mars is now difficult to see in evening twilight, but the slender crescent Moon might help you locate the red planet on the evening of the 18th.  While he will linger in the sky until solar conjunction in mid-November, your chances of seeing him from the city are slim at best.

Saturn, on the other hand, is approaching opposition from the Sun, and is now easy to spot in the late evening hours.  The ringed planet is located between the dim autumnal constellations of Aquarius and Capricornus and has virtually no bright competition except got the star Fomalhaut, which is much closer to the southern horizon.  Any small telescope will show the planet’s enigmatic rings and the yellow hue of his gaseous disc.

Jupiter was a nice bright companion for my Perseid viewing efforts.  The giant planet is the brightest object you will see from the late evening until dawn.  He is also located in a sparse star field, but a glance off to the east will show the Pleiades star cluster and the first rising stars of the Great Winter Circle, a reminder of cooler evenings and changing constellations to come as summer wanes to autumn.

 
 

Commander, Naval Meteorology and Oceanography Command | 1100 Balch Blvd. | Stennis Space Center, Mississippi 39529

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