image by Zond 8 andDon Davis
In 1959, the Soviet Union sent the Luna 3 spacecraft to photograph the farside of the Moon. Those grainy and very low resolution full Moon views tantalized us for a decade before Zond 8 radiod back to Earth a useful high Sun image of the farside. (Zond 3 provided the first semi-legible farside images, and Zond 6 provided some more, but Zond 8 was far better). This hemispheric view shows part of the visible hemisphere on the right (western edge of Oceanus Procellarum to Bailly), and the farside on the left. The main things that show up, as in all high Sun views, are albedo extremes. Left of center is Mare Orientale and the lava leakage of Lacus Veris, and thin curving lines of brightness mark the mountainous basin rings that define the concentric bull’s eye pattern. The bright rayed craters Glushko and Byrgis A (respectively north and south of the black circle of Grimaldi) are near the limb as seen from Earth, and on the farside are two other prominent ones. To the upper left is a dark-haloed bright crater with conspicuous rays. This is the 64-km wide Ohm. Its dark halo, like Tycho’s, is due to impact melt glass, and its 90° zone of avoidance in rays (to the northeast) shows that it was an oblique impact. Between Ohm and Orientale is a small, nameless fresh crater right on the 100° meridian, with rays much brighter than expected. One other thing this image doesn’t show is broad areas of darkness - the farside largely lacks mare lavas even though it has many impact basins.
This is said to be a Zond 7 image but I have seen it referred to as Zond 8 - I wish that all the Soviet imagery was well documented! And of course, Lunar Orbiter V acquired high quality farside images before Zond 7, but they were not high Sun views - and thereby showed topography much better. BASED ON PHIL STOOKE’S COMMENT BELOW I HAVE CHANGED THIS TO ZOND 8.
Rükl charts VII, VIII & p. 191.
Yesterday's LPOD: Out the Porthole
Tomorrow's LPOD: Postcard from the Edge