January Perigee Moon

jan21perigee-moon    Our Moon orbits around the Sun with the Earth and from our perspective on the Earth the Moon appears to circle around the Earth, however in reality the Moon orbits the Sun together with the Earth*.
   The 1.5-day old thin waxing crescent Moon reaches perigee this month on Wednesday January 21 th at 20:10 UT (2 pm CST). At that time the Moon will more or less be at a distance of 28.2 Earth diameters (359,645 km or 223,473 miles) from the Earth. Adding to the evening viewing will be four planets above the western horizon, three of which are naked-eye visible.The Moon will be close enough to both Mercury and Venus that all three will fit within the field of view of 7×50 binoculars. A little higher above the horizon is Mars within 2o from the planet Neptune, both of which will also fit within the field of view of 7×50 binoculars. Neptune at nearly 8th magnitude may be too dim to be visible with binoculars.
waxing-crescent-moom   This could be one of those opportunities to see a very young Moon, not a record youngest but nonetheless, worth trying to see. Because of the low angle of the Sun relative to the Moon the higher portions of crater rims and lunar mountains are in sunlight while their respective lower portions are still in shadow.
   On the side, so to speak, use binoculars or a low-power eyepiece and look at the unlit edge and along the cusps to see some of the higher peaks sparkling in sunset while their lower parts are still in shadow. The peaks look like they are not connected to the Moon as you can see in the lower left of this picture of a 2-3 day old waxing crescent Moon.

   *Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

1 thought on “January Perigee Moon

  1. Pingback: Moon Meets Planets | Bob's Spaces

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