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Looked Over, Then Overlooked?

by Geoff Chester | 13 February 2024

by Geoff Chester | 13 February 2024


The Moon, imaged 2021 March 21, 00:55 UT from Alexandria, Virginia
with an Explore Scientific AR102 10.2-cm (4-inch) f/6.5 refractor and a
Canon EOS Rebel SL2 DSLR and  a 1.4X tele-extender.
HDR processed to enhance "earthshine".

The Moon waxes in the evening sky this week, climbing northward along the ecliptic to join the bright stars of the Great Winter Circle.  First Quarter occurs on the 16th at 10:01 am Eastern Standard Time.  Look for the Moon just five degrees west of bright Jupiter on the evening of the 14th.  Luna cozies up to the Pleiades on the evening of the 16th.  The Moon ends the week among the stars of Gemini, passing just to the south of the star Pollux on the evening of the 20th.

We are now entering the time of the year when we see the most rapid change in the length of day.  From now through mid-April, we gain about two and a half minutes of sunlight each passing day.  If you like stargazing in the early evening hours, you only have a few more weeks to indulge in the view.  In less than a month, we will switch our clocks to Daylight Time, and evening twilight won’t end until nearly 9:00 pm.

This is prime time to get to know our nearest neighbor in space, the Moon.  Most of us will shoot the occasional glance toward the changing phases of our only natural satellite, but owners of binoculars or small telescopes should make an effort to scan her airless surface.  I still remember my first glimpse of the Moon through a telescope; from that moment onward the Moon became a place rather than an untenable light in the sky.  Luna’s landscape does not change much, but I still find myself inspecting her surface whenever I get the chance.  The features do not change; what we see today is essentially the same surface witnessed by the dinosaurs.  What does change is the slow creep of the “terminator” line, the division between the sunlit and dark parts as the Moon slowly moves against the background stars.  The region near the terminator is dominated by long shadows cast by mountain peaks and crater rims, and the shadows are absolutely black and stark.

Part of the fun of observing the Moon is that it is a well-mapped place whose features can be easily identified.  Many of the larger features bear names bestowed by early astronomers in the 17th Century, and almost every crater visible in a small telescope commemorates a prominent figure in astronomy and other sciences.  I own several lunar atlases that often accompany me to the telescope, but there are also many software atlases and lunar mapping apps to help you find your way around.

One aspect of lunar viewing is the scale of what you are seeing.  Despite its seeming closeness in the eyepiece, Luna is still very far away.  The smallest feature one can see with a good 12-inch telescope is about the size of the famous Meteor Crater outside of Flagstaff, Arizona.  It’s a very impressive feature to see when you are standing on its rim, but if it were seen at the Moon’s distance it would be a barely visible pit.

As the Moon waxes, she once again washes out the sky’s fainter stars.  Fortunately, we have the bright stars of the Great Winter Circle to enjoy despite the Moon’s glare.  The figure of Orion stands high in the south at around 8:00 pm local time, a distinctive figure whether seen from the inner city or the dark of the country.  Surrounding the Hunter are the other bright stars in the circle.  Sweep your binoculars around these stars to see their distinctive colors.  

Jupiter is still a great target for small telescopes during the early evening hours.  Old Jove gets a visit from the waxing crescent Moon on the evening of Valentine’s Day.  Jupiter is an appropriate target for this particular day; his four bright Galilean moons are named for his various romantic interests.

Once Jupiter sets it will be several hours before we see another bright planet, but you’ll have to wait until shortly before sunrise to see it.  Venus is now slowly drifting toward conjunction with the Sun, but you can still see her as morning twilight gathers.  Look for the dazzling planet a few degrees above the southeastern horizon about 45 minutes before sunrise.

 
 

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

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