Behold: the battered, pockmarked southern highlands of the Moon – home to impact sites old and young. To wit:
Captured on July 20, the lunar landscape features the Moon’s young and old, the large craters Tycho and Clavius. About 100 million years young, Tycho is the sharp-walled 85 kilometre diameter crater near centre, its 2 kilometre tall central peak in bright sunlight and dark shadow. Debris ejected during the impact that created Tycho still make it the stand out lunar crater when the Moon is near full, producing a highly visible radiating system of light streaks, bright rays that extend across much of the lunar near side. In fact, some of the material collected at the Apollo 17 landing site, about 2,000 kilometres away, likely originated from the Tycho impact. One of the oldest and largest craters on the Moon’s near side, 225 kilometer diameter Clavius is due south (above) of Tycho. Clavius crater’s own ray system resulting from its original impact event would have faded long ago. The old crater’s worn walls and smooth floor are now overlayed by smaller craters from impacts that occurred after Clavius was formed. Observations by the Stratospheric Observatory for Infrared Astronomy (SOFIA) published in 2020 found water at Clavius. Of course both young Tycho and old Clavius craters are lunar locations in the science fiction epic 2001: A Space Odyssey.
The Moon: changing its appearance nightly depending on numerous factors but nonetheless entirely predictable. To wit:
As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly visible. The featured video animates images taken by NASA’s Moon-orbiting Lunar Reconnaissance Orbiter to show all 12 lunations that appear this year, 2021. A single lunation describes one full cycle of our Moon, including all of its phases. A full lunation takes about 29.5 days, just under a month (moon-th). As each lunation progresses, sunlight reflects from the Moon at different angles, and so illuminates different features differently. During all of this, of course, the Moon always keeps the same face toward the Earth. What is less apparent night-to-night is that the Moon‘s apparent size changes slightly, and that a slight wobble called a libration occurs as the Moon progresses along its elliptical orbit.
Behold: the spectacular result of a single exposure and a lot of careful planning. To wit:
The photographic goal was achieved by precise timing — needed for a nearly full moon to appear through the eye-shaped arch, by precise locating — needed for the angular size of the Moon to fit iconically inside the rock arch, and by good luck — needed for a clear sky and for the entire scheme to work. The seemingly coincidental juxtaposition was actually engineered with the help of three smartphone apps. The pictured sandstone arch, carved by erosion, is millions of years old and just one of thousands of natural rock arches that have been found in Arches National Park near Moab, Utah, USA. Contrastingly, the pictured Moon can be found up in the sky from just about anywhere on Earth, about half the time.