On March 14, the inhabitants of the Earth will be able to see the first total lunar eclipse since November 2022. It will be observed in North and South America, as well as in Western Europe and West Africa.
At this time, the Blue Ghost spacecraft built by Firefly Aerospace (its landing is scheduled for March 2) will have to work on the surface of the Moon. The IM-2 mission from Intuitive Machines is also due to arrive at the Moon (its exact landing date is still unknown). All this raises a legitimate question: what will these vehicles see on the day of the eclipse and will they be able to photograph it?
Solar eclipses on the Moon
Lunar eclipses occur when the Moon passes through the Earth’s shadow. Consequently, at that moment our planet completely covers the Sun in the lunar sky – and there is a solar eclipse.
Solar eclipses on the Moon have significant differences from Earth’s eclipses in several main points. First, they last much longer than on our planet. The duration of the total phase of an eclipse can be measured in hours. Second, while on Earth the total phase is observed only in a rather narrow band, on the Moon it is visible on the entire side facing our planet, except for the bottom of the deepest polar craters.
Another important difference is that, unlike the Moon, the Earth has an atmosphere. Therefore, when our planet covers the Sun, a bright ring (also called a “diamond”) forms around its disk due to the refraction of the sun’s rays. Because of this effect, the rays passing through the Earth’s atmosphere color the lunar surface in a characteristic red-brown color.
Photos of solar eclipses from the Moon
That’s the theory. But did the humans and spacecraft on the Moon photograph solar eclipses?
It should be realized that taking pictures of eclipses has never been the priority of space missions. Moreover, engineers usually avoid pointing cameras at the Sun and close to it to avoid damage to the optics.
Nevertheless, we still have a few examples of such photography. The first spacecraft in history to photograph a solar eclipse on the Moon was the American Surveyor 3. It did it on April 24, 1967.
On February 9, 2009, this achievement was repeated by the Japanese probe “Kaguya”, which was in a selenocentric orbit. It too succeeded in capturing the diamond ring around our planet.
As for people, the crew of Apollo 12 had the opportunity to observe such a sight with their own eyes. During the return to Earth, the ship crossed the Earth’s shadow. At that moment, the apparent size of our planet was 15 times the size of the solar disk. Despite this, the astronauts also happened to see the “diamond” ring. According to their memories, its colors were constantly changing, while the planet remained completely black. In this darkness, they periodically saw flashes of terrestrial thunderstorms.
When the astronauts’ eyes adapted to the dark part of the Earth, they were able to distinguish the outlines of continents (in particular, they were able to see India), and even the lights of cities. In the center of the Earth’s disk, they saw a large bright circle, which turned out to be the reflection of the full Moon reflected from the Indian Ocean.
Orbiting around the Moon, LRO in particular, also collected data on temperature changes on its surface during eclipses. They turned out to be uneven. While temperatures did drop in many parts of the Moon, they remained relatively high in some of its seas (e.g., the Oceanus Procellarum and the Mare Tranquillitatis). The same effect was also observed among large craters with basalt bottoms, as well as the youngest lunar craters.
It is currently unknown whether the Firefly Aerospace and Intuitive Machines missions will attempt to photograph the upcoming eclipse. But if they do, we will be treated to some very rare and unusual images.
