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NASA videos show what sunsets look like elsewhere in the galaxy

On other planets, blue skies and red sunsets aren't the norm.

NASA
  • 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.

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 modeling 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 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," NASA wrote in a blog post. "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 color 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 light of certain wavelengths to appear more visible to the human eye.

"When sunlight — which is made up of all the colors of the rainbow — reaches Uranus's atmosphere, hydrogen, helium and methane absorb the longer-wavelength red portion of the light," NASA wrote. "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 color as day turns to 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.

An illustration of Rayleigh scattering

An illustration of Rayleigh scattering.

Scientificprotocols via YouTube

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

sunset on Mars

A sunset on Mars. Taken by the Viking 2 Lander on June 14, 1978, this was the first photo of an alien sunset.

NASA

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 harbor life already.

Hints of the 4th dimension have been detected by physicists

What would it be like to experience the 4th dimension?

Two different experiments show hints of a 4th spatial dimension. Credit: Zilberberg Group / ETH Zürich
Technology & Innovation

Physicists have understood at least theoretically, that there may be higher dimensions, besides our normal three. The first clue came in 1905 when Einstein developed his theory of special relativity. Of course, by dimensions we’re talking about length, width, and height. Generally speaking, when we talk about a fourth dimension, it’s considered space-time. But here, physicists mean a spatial dimension beyond the normal three, not a parallel universe, as such dimensions are mistaken for in popular sci-fi shows.

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Does conscious AI deserve rights?

If machines develop consciousness, or if we manage to give it to them, the human-robot dynamic will forever be different.

Videos
  • Does AI—and, more specifically, conscious AI—deserve moral rights? In this thought exploration, evolutionary biologist Richard Dawkins, ethics and tech professor Joanna Bryson, philosopher and cognitive scientist Susan Schneider, physicist Max Tegmark, philosopher Peter Singer, and bioethicist Glenn Cohen all weigh in on the question of AI rights.
  • Given the grave tragedy of slavery throughout human history, philosophers and technologists must answer this question ahead of technological development to avoid humanity creating a slave class of conscious beings.
  • One potential safeguard against that? Regulation. Once we define the context in which AI requires rights, the simplest solution may be to not build that thing.

A new hydrogel might be strong enough for knee replacements

Duke University researchers might have solved a half-century old problem.

Lee Jae-Sung of Korea Republic lies on the pitch holding his knee during the 2018 FIFA World Cup Russia group F match between Korea Republic and Germany at Kazan Arena on June 27, 2018 in Kazan, Russia.

Photo by Alexander Hassenstein/Getty Images
Technology & Innovation
  • Duke University researchers created a hydrogel that appears to be as strong and flexible as human cartilage.
  • The blend of three polymers provides enough flexibility and durability to mimic the knee.
  • The next step is to test this hydrogel in sheep; human use can take at least three years.
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Technology & Innovation

Predicting PTSD symptoms becomes possible with a new test

An algorithm may allow doctors to assess PTSD candidates for early intervention after traumatic ER visits.

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