NASA Finds Sunset in Space

One of the ways to observe the beauty of the world is to watch as the Sun slowly sets in the west, creating a mirage of colours in the sky. Now, imagine if you were observing that same sunset while sitting on Saturn or Venus or Mars.

“Have you ever wondered what a sunset on Uranus might look like?”

You can’t visit Mars, Venus, Uranus or Titan in person, but you can enjoy their lovely sunsets.

A NASA scientist created animated simulations of how sunsets likely appear on Mars, Venus, Uranus, and Titan, Saturn’s largest moon.

Sunsets appear differently on other planets because of differences in the atmosphere, which scatters light in unique ways.

Studying alien atmospheres helps scientists better understand atmospheric processes on Earth, and helps narrow the search for habitable planets.

NASA’s new simulation:

New video simulations from NASA offer a glimpse of what sunsets might look like on other planets.

Created by Geronimo Villanueva, a planetary scientist at NASA’s Goddard Space Flight Center, the simulations are part of a computer modelling tool that scientists could someday use to study extraterrestrial atmospheres on probe missions. 

Villanueva simulated how skies might look as day turns to night on Venus, Mars, Uranus, and Saturn’s largest moon, Titan.

The colour of the sunset:

The animations show all-sky views as if you were looking up at the sky through a super-wide camera lens from Earth, Venus, Mars, Uranus, and Titan. The white dot represents the location of the Sun.

The simulations reveal sunsets that look quite different from those on Earth. On Uranus, for example, the sky morphs from a royal blue to a hazy brownish-yellow. Why the difference? The colour of the sky on any planet is determined by the unique blend of molecules in the atmosphere. 

When incoming sunlight passes through the atmosphere, these molecules scatter light in specific ways, causing the light of certain wavelengths to appear more visible to the human eye.

How does NASA find the colour of the light?

When sunlight which is made up of all the colours of the rainbow reaches Uranus’s atmosphere, hydrogen, helium and methane absorb the longer-wavelength red portion of the light. The shorter-wavelength blue and green portions of light get scattered as photons bounce off the gas molecules and other particles in the atmosphere. A similar phenomenon makes Earth’s sky appear blue on a clear day.

So, why do skies change colour as day turns to the night? During the day, sunlight travels through the atmosphere to our eyes on a relatively short path. But as the sun sets, light must take a longer path through the atmosphere, which provides more opportunities for shorter wavelengths (blue) to be scattered.

The result is a red sunset, produced by an optical phenomenon called Rayleigh scattering.

Villanueva’s simulations are now featured on NASA’s Planetary Spectrum Generator, an online tool for studying the atmospheres and surfaces of distant planets. Studying alien atmospheres not only helps scientists better understand atmospheric processes on Earth, but also gives them a clearer idea of which planets may be habitable or harbour life already.

Image Courtesy: www.republicworld.com

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