Sunsets on other worlds have long been a staple of science fiction films, but what would such events really look like? Fortunately, we have NASA to answer such questions, and they have not failed us, providing a video comparing the sunsets we see on Earth with those an observer might witness on the Solar System's other planets, and one moon. They've even included the setting of a different star, as seen from one of the planets of the TRAPPIST-1 system, although there is a lot more guesswork to how that one would look.
Dr Geronimo Villanueva of the Catholic University of America is working on a possible future mission to Uranus, which is on NASA's shortlist for future space probes. He has been investigating the way the Uranian atmosphere would scatter the Sun's light. By modeling what we expect to see, Villanueva is providing a point of comparison. If a future craft sends back images that look different, astronomers will know it's time to reconsider what we think we know about Uranus's composition and how those gasses behave.
One way to drum up support, and therefore funding, for such a project is to give the public a taste of what we might see. Villanueva teamed up with James Tralie of NASA's Goddard Space Flight Cente3r to make the simulation of sunsets as seen through the hydrogen, helium, and methane of Uranus' upper atmosphere available to the world. But why stop there? Along with familiar Sunsets on Earth, under both clear and overcast conditions, he's produced some for Mars, Venus and Titan, along with TRAPPIST-1e, the innermost of the three planets of that system considered to have the right temperature for life. Comparisons with real Earth and Mars simulations help verify the simulations' accuracy for the other cases.
Granted the Earth Sunsets don't look like what you are used to seeing because these images are as the sky would look through an extra-wide angle camera lens, rather than to the naked eye. Any future probe to Uranus may be equipped with multiple cameras, but it's likely at least one of them will be trying to capture as much of the planet as possible as it makes its final dive.
Of course in the cases of the TRAPPIST worlds, we only know the characteristics of their red dwarf star and the planets' distances to it. Although this tells us how bright the star would look as it set, and its dominant colors, we don't know anything about the composition of TRAPPIST-1e's atmosphere, or even if it has one, which could make a substantial difference to the Sunset. Consequently, this part of the video has more guesswork involved than the rest.
An alternative version shows the sunsets side-by-side for comparison.
If these videos have left you wanting more, take a look at these more artistic – but still scientifically based – images of the Sun, often setting, from various parts of the Solar System.