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How Dark is Your Sky? Ask Orion...

Feb. 14, 2023 | By Geoff Chester, USNO Public Affairs

Comet C/2023 E3 (ZTF), imaged 2023 February 14, 02:43 UT
from Alexandria, VA with an Explore Scientific AR102 10.2-cm (4-inch) f/6.5 refractor
Optolong L-eNhance narrowband filter, and a ZWO ASI183MC CMOS color imager

The Moon skirts the southern horizon during morning twilight as the week opens, passing through the rising stars of the summer sky.  New Moon occurs on the 20th at 2:06 am Eastern Standard Time.  If you have a clear view of the southeast horizon you can see Luna nestled among the stars of the “Teapot” asterism of Sagittarius, the Archer before dawn on the morning of the 16th.  Try to view her hairline crescent in the west when she returns to the evening sky on the evening of the 21st.

The Moon’s absence from the overnight hours means that it is time to do a little bit of citizen science by supporting the
Globe at Night sky-awareness program.  It was established in 2009 as a project of the International Year of Astronomy, and now some 20,000 people contribute their sky observations annually.  This month the target constellation is Orion, the Hunter, which is the perfect star pattern to observe for novice skywatchers.  Orion is populated by bright stars that form a distinctive pattern, and it is usually one of the first constellations that people recognize.  I remember as a youngster being fascinated by the Hunter’s three “Belt Stars”, which formed a perfect straight line of blue-tinted luminaries.  Orion is visible from every inhabited part of the globe, and he is easily visible from major urban areas.  

You will find Orion crossing the meridian at around 8:00 pm local time this week, well after the end of astronomical twilight.  To make an observation for Globe at Night, simply find Orion in your sky, then pull up the
Globe at Night web app on your computer of smart phone.  Wait about ten to fifteen minutes for your eyes to adapt to the dark, and avoid standing in the direct glare of streetlights.  No match your view of Orion with the magnitude charts on the app, then fill out the online form to record your data.  Your observation will help increase the awareness of our brightening skies and help others to find darker locations to enjoy the nighttime views.  

If you are away from home for the President’s Day weekend, take some time to compare the sky at your chosen destination to the sky above your home.  Here in the Washington, DC area you will have a great opportunity to see the splendid winter sky from Sky Meadows State Park near Paris, Virginia on the evening of the 18th.  The
“Astronomy for Everyone” program features a “sky tour” and multiple telescopes provided by local amateur astronomers.  There is a nominal parking fee to enter the park, but the program and viewing are free. 

If you visit Sky Meadows or another dark sky site, this is probably the last chance you will have to see the “Green Comet”, aka Comet C/2022 E3 (ZTF).  You will definitely need binoculars or a small telescope to see it, but its placement is ideal for “prime time”.  On the evening of the 14th it is just over one degree east of the bright star Aldebaran, the red-hued “eye” of Taurus, the Bull.  Over the next several nights it drifts to the south, moving just under two degrees per day.  On the evening of the 18th the comet will be about two degrees west of the small galactic star cluster NGC 1662.  The two objects should both be visible in a low-power 3- or 4-inch telescope.  The comet is now receding from the Sun and Earth.  This will be your last good opportunity to see it for…well…eternity.

Venus continues to climb higher in the western sky at dusk.  You should have no trouble finding her as she is the brightest object in the sky after the Sun and Moon.  She appears to be sprinting toward Jupiter, halving the gap between the two bright objects by the start of next week.

While Venus races away from the Sun, Jupiter is losing ground to Old Sol.  The giant planet doesn’t spend much time above the atmospheric limit for steady viewing, so the best time to view him is during twilight.  By 9:00 pm he has set.
Mars continues to fade as the distance between him and Earth increases, but he still has some prominence in the night sky.  You will find him high in the south, crossing the meridian at around 7:00 pm.  He is gradually picking up speed on his eastward trek around the sky, and he will remain visible in the evenings well into the summer.

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