NASA simulation shows a kaleidoscope of sunsets on other worlds

Have you ever wondered what a sunset would be like on Uranus?

As you can see in the animation above, a Urania sunset is a deep blue that fades into royal blue with hints of turquoise. This greenish blue color comes from the interaction of sunlight with the planet’s atmosphere. When sunlight, which is made up of all the colors of the rainbow, reaches the atmosphere of Uranus, hydrogen, helium, and methane absorb the red portion of the longest wavelength light. Portions of shorter wavelength blue and green light scatter when photons bounce off gas molecules and other particles in the atmosphere. A similar phenomenon makes Earth’s sky appear blue on a clear day.

Gerónimo Villanueva, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, created the simulations of the sunset while building a computer modeling tool for a possible future mission to Uranus, a frozen planet in the system. outdoor solar. One day, a probe could descend through Urania’s atmosphere, with Villanueva’s tool that helps scientists interpret the light measurements that will reveal its chemical composition.

To validate the accuracy of his tool, Villanueva simulated known sky colors from Uranus and other worlds, some of which are shown above. The animations show that the Sun appears to be setting from someone’s perspective on these worlds. As these worlds rotate away from sunlight, which is what happens during a sunset, photons scatter in different directions depending on the energy of the photons and the types of molecules in the atmospheres. The result is a beautiful palette of colors that would be visible to those on these worlds.

The animations show views of the entire sky as if you were looking up into the sky through a super-wide camera lens of Earth, Venus, Mars, Uranus, and Titan. The white dot represents the location of the sun. The halo of light seen towards the end of sunset on the hazy Earth occurs due to the way light is scattered by particles, including dust or fog, that are suspended in clouds. The same is true of the Martian halo. Also on Mars, the sunset changes from a brownish to a blue color because Martian dust particles disperse the blue color more effectively.

These sky simulations are now a new feature of a widely used online tool called the Planetary Spectrum Generator, developed by Villanueva and his Goddard colleagues at NASA. The generator helps scientists replicate how light is transferred through the atmospheres of planets, exoplanets, moons, and comets to understand what their atmospheres and surfaces are made of.

For a less technical and more contemplative perspective on alien sunsets, watch this short movie:

---

---