Updated

Updated · Space.com · Sep 19

Moon Watchers Get 5 Telescope Targets for Sept. 19 as 62-Mile Straight Wall Appears

Updated

Updated · Space.com · Sep 19

Moon Watchers Get 5 Telescope Targets for Sept. 19 as 62-Mile Straight Wall Appears

Q: Why is the exact spot where Apollo 11 landed impossible to see from Earth, even with powerful backyard telescopes?

The Apollo 11 landing spot cannot be seen from Earth because it is far smaller than the resolving power of backyard telescopes. From Earth, even a good amateur telescope is limited by diffraction and by Earth’s atmosphere, which usually blurs detail to around 1 to 3 arcseconds. That translates to features on the Moon several kilometers across. The hardware at Tranquility Base—the lunar module descent stage, experiments, flag area and astronauts’ tracks—is only a few meters to a few tens of meters in size. At the Moon’s distance, those objects span only a tiny fraction of an arcsecond, far below what ground-based telescopes can separate. Even the exact landing point itself is just one location within a broader area, not a large visible feature. What observers can do is locate the general region near Mare Tranquillitatis, close to the craters Ritter, Sabine and Moltke, as the guide suggests. But identifying the precise Apollo 11 site requires images taken from lunar orbit, such as those from NASA’s Lunar Reconnaissance Orbiter, which photographs the site at much higher resolution. So the limit is not that the site is on the wrong side of the Moon or hidden in darkness. It is simply too small and too fine in detail to be resolved from Earth with even powerful backyard instruments.

3 articles · Updated · Space.com · Sep 19

Sept. 19’s International Observe the Moon Night guide highlights five lunar targets timed to the moon’s first-quarter phase, when the half-lit disk hangs low near Sagittarius.
A 4-inch telescope can show the 373-mile Montes Apenninus, craters Plato, Archimedes and Eratosthenes, Mare Crisium, and Rupes Recta — a 62-mile fault scarp near the terminator.
Tranquility Base also makes the list: observers can locate Apollo 11’s landing area by tracing a line between the Sabine and Moltke craters on the Sea of Tranquility’s southwestern shore.
Larger 6- to 8-inch scopes reveal finer detail, especially Eratosthenes’ western rim, while Apollo 11 hardware remains too small to see from Earth.
The selection is designed as a practical observing roadmap for the annual public moonwatching event, with additional virtual and in-person participation options available.