A solar eclipse is one of the most impressive astronomical spectacles that we can see with the naked eye from Earth. If you have ever seen one, you will hardly forget it. There are even those who dedicate themselves to searching for these phenomena , accumulating up to twenty of these experiences. What makes solar eclipses so incredible is the fantastic coincidence that the Moon and Sun are roughly the same apparent size as seen from the surface of our planet. This allows us to see annular eclipses from time to time and also makes total eclipses especially interesting.
This is a cosmic coincidence that we have been lucky enough to experience. You may know that the Moon is constantly moving away from Earth . It does so at a very slow rate, less than four centimeters a year , but over millions of years this slow rate accumulates. 500 million years ago, when animals were beginning to conquer terrestrial habitats, the Moon would have been too big. Total eclipses occurred at that time, but as the satellite dominated the star they would not be so impressive . In the future, the opposite will happen. The Moon will have moved so far away from the Earth several hundred million years from now that it will not be able to completely block the Sun in the sky , thus missing out on total solar eclipses, and making annular eclipses less spectacular.
Of course, eclipses are not something exclusive to our planet , and they occur on the surface of any body that has a satellite orbiting around it or even on the satellites themselves. As long as the relative orientation is correct, all the satellites in the solar system will be able to experience a total solar eclipse by their corresponding planets . However, not all planets will have eclipses of all of their moons.
Of course Mercury and Venus will not have eclipses of any kind as they have no moons . Mars has two very small moons , Phobos and Deimos, but they orbit very close to its surface. This makes Phobos, the closest and largest of its moons, capable of causing partial solar eclipses .
Despite not causing a complete occultation of the star, they are enough to be visible to the naked eye and are probably a sight to behold.
As we move away from the Sun, the easier it is to witness an eclipse of the Sun, since it occupies a smaller size in the sky and more objects will be able to hide it . For example, if we go to Jupiter we can witness eclipses of its four largest moons, Io, Europa, Ganymede and Callisto , the moons that were discovered in 1610 by Galileo Galilei. These satellites are similar in size or even larger than our moon but orbit at greater distances, with Callisto being almost 2 million kilometers from Jupiter . However, at that distance, the Sun has an angular size about five times smaller than from Earth , which means that these four satellites are able to cover it without any problem.
This will have the consequence that several eclipses can be witnessed simultaneously on the surface of the gas giant and even that, on very rare occasions, the shadow of two of its satellites partially coincide, being able to see a double eclipse from that specific point on its surface.
If we continue to move away from the Sun, more and more satellites star in solar eclipses. On Saturn there are up to seven moons capable of completely obscuring the Sun. These include not only the largest and most well-known moons, such as Titan, Rhea or Enceladus , but also less popular ones, such as Mimas or Janus , which are smaller at just a few hundred kilometers in size , but orbit much closer to Earth. ringed giant.
In the case of Uranus, about 15 of its moons will be able to completely cover the Sun , which at this distance of about 2,800 million kilometers is about 19 times smaller than seen from Earth. The Sun is so small from Uranus that satellites of just 40 or 50 kilometers in diameter are capable of hiding and others like Ariel, with its little more than 1000 kilometers in diameter, occupies about 12 times more in the sky of Uranus than the star.
From Neptune there are eight satellites large enough to completely hide the Sun. Most of them do so without major problems, resulting for example Triton about 24 times larger than the Sun. However, the Hippocampus satellite of about 35 kilometers in diameter is barely able to hide the star , so it will be able, depending of the eccentricity of its orbit, of offering annular eclipses.
Even from Pluto we could observe solar eclipses and not only from its (relatively) huge companion Charon, which dominates Pluto’s skies unquestionably. Its smaller moons, just a few tens of kilometers in size, would also be capable of obscuring the Sun , although perhaps not for the entire orbit of the dwarf planet. Nix and Hydra , with diameters of about 40 kilometers , would hide the Sun even in the most distant parts of Pluto’s orbit , but Styx and Kerberos would have it more complicated, hiding it in the closest parts, but falling short in the remote regions.
In short, total solar eclipses are very common in our solar system and dozens of different satellites are capable of causing them on the surface of their planets. However, annular solar eclipses turn out to be much rarer , being only possible on Neptune and at some specific points in Pluto’s orbit, as well as on our planet.
