June Perigee Moon at Descending Node

10jun-perigee   The Moon reaches perigee, (minimum distance from Earth), this month on Wednesday June 10th at 4:44 UT (11:44 pm CDT Tuesday June 13th). At that time the Moon will more or less be at a distance of 28.98 Earth diameters (369,711 km or 229,728 miles) from the Earth.
   Does our Moon actually go around the Earth as this graphic shows? 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*

apr17-descending-node   Also on Wednesday June 10th at 23:31 UT, (5:31 pm CDT), our Moon will be crossing the plane of the ecliptic moving south. This is known as the descending node, one of two intersections the Moon’s orbital path (dark green line) has with the ecliptic.

   The 23-day old waning crescent Moon is just past last or 3rd quarter phase. The thin waning crescent Moon is conveniently lined up with the left side the Square of Pegasus, an asterism formed with three stars from the constellation Pegasus the Winged Horse, and one star from the constellation Andromeda the Princess. Nearby is another asterism, the “Circlet”, part of the western fish of the constellation Pisces the Fishes.

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

   Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

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.

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