How would the sun be immersed below the horizon in a long (17 hours) day on Uranus? Or what would a late night sunset look like on Mars when we finally got there? Thanks to some NASA computer models, these scenarios are now a little easier to imagine.
What makes a sunset is the interaction of sunlight – which includes all the colors of the rainbow – along with the gases and dust in the atmosphere. Less atmosphere, less impressive is the sunset.
Planetary scientist Geronimo Villanueva, of NASA’s Goddard Space Flight Center in Greenbelt, has created simulations of how sunsets could appear on Venus, Mars, Uranus, the moon of Saturn, Titan and Trappist-1e.
The shows are quite spectacular, as you can see below, with scenes shown as if you are pointing a camera with a wide angle lens towards the sky.
On Venus, for example, a bright yellow dissolves into orange, brown and then black as the sun disappears. Since the planet rotates on its axis so slowly, you should wait approximately 116 times longer than Earth, which is just over half of a Venusian year.
Not that you’re settling down to watch the sun set over Venus, with its dense, CO2-rich atmosphere, intense surface pressure and average temperatures of 471 degrees Celsius (880 degrees Fahrenheit).
These simulations are not just fun to watch. They also have a serious scientific point for them: preparations for a potential survey mission to Uranus. There’s still a lot we don’t know about the gas planet, and any reading of its atmosphere would need to interpret the light levels reaching the sensors of the spacecraft.
With the data from this simulation on board, the probe would have had a better idea of what it was looking for and could have better assessed the composition of the atmosphere while absorbing sunlight – what wavelengths were scattered and what.
Here is another look at the beautiful sunset models:
The new models are now part of the planetary spectrum generator, built by Villanueva and his colleagues, which is used to interpret the light reaching our telescopes and to decode it to try to understand what the atmosphere is like on other worlds.
Mars is the only other planet on which we have realistic possibilities to live, unless we spend all our time in an incredibly strong and robust floating spaceship capable of withstanding extremes of pressure and temperature.
Villanueva’s simulation shows how the Martian sunset would appear to its inhabitants, with the atmosphere creating a mix of muddy brown and bright yellow colors as the sun disappears behind the horizon.
In fact, these simulations are only part of the story – as the Curiosity rover has already shown, days on Mars can end with a distinctly blue-ish tinge, while dust disperses the red wavelengths of light away from view, letting the blue wavelengths hit our eyes. If only we could go and see for yourself.