Libration in Longitude

Images of the full Moon taken 4 months apart showing the Libration in Longitude - Libration in longitude results from the eccentricity of the Moon's orbit around Earth; the Moon's rotation sometimes leads and sometimes lags its orbital position. Images by Pipp Stakkert taken with the Observatory Altair Astro 66 mm Doublet Refractor.

" The recent full Moon at Perigee - ie. when it is closest to Earth and brightest, provided an opportunity for Pipp Stakkert to try out the new 0.6x focal reducer and field flattener with the little Altair Astro scope and the Canon 600D DSLR camera. The image on the right above and enlarged below, was taken with this set up. It was quite amazing to watch Pipp take a series of images with the camera and telescope both hand held - using the scope as a camera telescopic lens. The Moon at perigee was so bright that the images were taken at ISO 100  - exposure 1/2500 and f =240mm.

If you look carefully at the above two images, you can see that in October 2017, Grimaldi is further from the eastern limb and Mare Crisium is closer to the western limb than in the image taken at the end of January 2018. This is clear evidence of  'Libration in Longitude'. You can also see some 'Libration in Latitude', with the Moon in January 2018 showing more of the South Pole and less of the North Pole than in October 2017."  - Kurt Thrust acting CEO and current Director of the Jodrell Plank Observatory.

From a stack of 20 exposures 31st January 2018.