May Perigee Moon in Conjunction with Venus

   Our Moon reaches perigee, (closest distance from Earth), for this orbit on Thursday May 17th. At that time the Moon will be at a distance of 28.52 Earth diameters (363,800 km or 226,055 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*

   Thursday evening May 17th, shortly after sunset local time (8:26 CDT), look toward the western horizon for a conjunction between a thin 2.5-day young waxing crescent Moon and the inner planet Venus. The two will be about 5.5o apart. The respective apparent magnitudes of Venus (-3.95), and the Moon (-10.22) will make an interesting contrast. Despite the difference in the apparent magnitude of Venus and the Moon, which one appears brighter? Do they appear to be similar in apparent magnitude, or brightness?

   Using binoculars the Moon and Venus will be seen as forming the base of a small triangle with the open star cluster, M-35 (apparent magnitude 5.5) forming the point of the triangle.
   (the size of Venus and Moon are not to correct scale and in this graphic have been enlarged for the image)

   *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?”


Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to go to bobs-spaces.

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