Occultation of Selene and Aphrodite

July 18, 2010


Photographer: Anthony Ayiomamitis
Summary Author: Anthony Ayiomamitis

On May 16, 2010, for the second time in three years, Europeans were able to observe a daytime occultation of Venus by the Moon. This time the Moon was very young; less than two and a half days old. Only 6.6 percent of its surface was illuminated as viewed from near Athens, Greece on the afternoon of the sixteenth. It was quite challenging to capture this occultation since strong winds were jarring my scope and because the Sun had not yet set, thus the sky near Aphrodite and Selene was still noticeably bright.

Although occultations can occur in a variety of ways, the heavenly body most often involved is our own Moon which, inevitably, will pass in front of and/or eclipse background stars as well as other planets and even asteroids. These occultations are important in studying the lunar limb and its profile. The great difference in magnitude between the Moon (at any phase) and any planet makes photographing them a difficult proposition. On this day, Venus glowed at -4.0 magnitude while the crescent Moon was approximately 15 times brighter at a magnitude of -6.8.

Photo details: Telescope: AP 160 f/7.5 StarFire EDF; Mount: AP 1200GTO GEM; Camera: Canon EOS 5D Mk I; Baader UV/IR-Cut Filter; Exposures: 2 x 1/5000 seconds; ISO 800; RAW Image Format; manual Mode; from 11:48:30 UT+3 11:49:30 UT+3; Software: Digital Photo Pro V1.6.1.0; Photoshop CS2; Processing: RAW to TIFF (16-bit) Conv Resampling; JPG Compression