Mars Waning and Receding | Rod Pommier

Rod Pommier
Location of photo
Pommier Observatory, Portland, OR, USA
Date/Time of photo
2012-03-07 through 2012-04-17
Celestron Compustar C14 Telescope/Mount with Tele Vue 2x Power Mate (f/22) Point Grey Research Flea3 Color Camera. Best 300 frames out of 1500 at 24 fps for left image, best 400 frames out of 3000 at 60 fps for center and right images. Seeing conditions were poor (Damian Peach scale), but clear weather in March and April are rare in Oregon, so any data are better than no data.
Earth passed between the Sun and Mars, known as opposition, on 2012-03-03 and made closest approach on 2012-03-05. Around these times, Mars ‘disk is illuminated in full phase and exhibits its greatest apparent diameter. Subsequently, Earth pulls ahead of Mars and we look back on the morning terminator of a waning gibbous Mars whose disk shrinks as it seemingly recedes in the distance. These images show that even small changes in disk size have a profound impact on the apparent sizes of surface features, like Acidalia Planitia, Margaritifer Terra, Sinus Meridiani, and Syrtis Major, making them progessively more challenging to capture.