If you stand on other planets in the solar system, what kind of sunset will you see? Here comes the simulation.
Recently, thanks to Geronimo Villanueva, a planetary scientist at NASA's Goddard Space Flight Center, we have a tool that can simulate the surface environment of other planets and let us experience the feeling of landing on other planets.
Recently, Villanueva participated in the Uranus exploration project that NASA may start in the near future and was responsible for developing computer modeling tools for this project. If NASA really sends a probe to Uranus, it will use this tool to obtain the spectrum and analyze it when it enters Uranus' atmosphere. When developing this tool, Villanueva had a whim and created a sunset simulation of the surface environment of many solar system celestial bodies, including Uranus.
At the beginning of his last video, Villaneuva first compared the earth sunsets in clear, dense fog and dark weather to help everyone understand the possible color difference.
We know that the color of the planet's sky depends on what its atmosphere is made of. Sunlight itself is white, but it will be scattered by gas molecules when it hits the atmosphere, and finally it will show different colors when it spreads to the surface. For example, under the influence of Rayleigh scattering, the shorter the wavelength, the more blue scattering, so it finally appears beautiful blue in our eyes.
Sunsets on Uranus also show a strong blue color, but the fundamental reason is different from that on Earth. Although this also comes from the scattering of sunlight in the atmosphere, the blue color is caused by a lot of hydrogen, helium and methane. As the sun gets closer and closer to the horizon, it finally sets completely, and the bright blue gradually darkens, and finally it completely darkens.
However, such sunsets are not always seen on Uranus. This is because Uranus' axis of rotation and orbit of revolution have an inclination of 98, so it almost "lies down" and rotates. Because it has been in period of revolution for 84 years, the average daytime on each side is as long as 2 1 year, which is the summer here. At this time, there is no sunset unless it is near the equator. On the other hand, during the day, you can't see the sunset. Only when the axis of rotation is not facing the sun and the appropriate position is selected can the sunset on the surface of Uranus be seen.
Besides Uranus, Villanueva also simulated other celestial bodies.
On the surface of Venus, the sunset turns hazy yellow. When the sun goes down, the color of the sky turns dark brown. Venus' sunset is this color because Venus' atmosphere is very thick and sunlight is very difficult to penetrate. The atmospheric pressure on the surface of Venus is 93 times that of the earth, mainly carbon dioxide. The terrible greenhouse effect makes its surface temperature even reach 500 degrees Celsius!
On Mars, the sunset takes on a completely different color. In the evening on Mars, the sky will be hazy taupe with bright light. If you look closely, you will also find that the sun actually appears slightly blue before sunset.
In fact, the sunset on Mars does not depend entirely on simulation. We have witnessed such a spectacular scene many times. This became possible when the human lander landed on its surface. Sunsets on Mars have become commonplace for the rover Opportunity and the new rover in the follow-up mission.
On April 20 1515, the rover Curiosity took a set of sunset pictures at the Gaelic Crater on Mars. This animation contains four photos, all taken by Mastcam camera on Mars, and the time interval is 6 minutes 5 1 second.
In addition, the model also simulates the environment of Titan. Scientists believe that Titan is one of the most promising celestial bodies for life, and NASA also plans to launch a probe for field investigation in the 1930s. At the same time, Titan is also the only satellite with a complete atmosphere, so Villanueva also simulated the sunset on its surface.
Like Venus, Titan is orange even when viewed from space. When you look at the sky on the surface, you will also see such a color. As the sun sets, the sky gradually turns dark brown. The reason why the sunset here is like this is because the proportion of nitrogen in Titan's atmosphere is 95%, which is higher than that of the earth. In addition, the concentration of methane and other carbon-containing organic molecules is relatively high.
At the same time, they also simulated the surface environment of the exoplanet trappist-1e. TRAPPIST- 1, the host star of this planet, has seven planets and is one of the celestial bodies with the most exoplanets. The latest research shows that three or four of its seven planets may be located in the livable zone, and TRAPPIST- 1e is one of them.
It is reported that the software developed by Villanueva and his colleagues at NASA Goddard Space Flight Center is part of the planetary spectrum generator, which has been released on the Internet. For astronomers, they can transmit the light of stars through the atmospheric models of planets, comets, satellites and other celestial bodies, so as to analyze the material composition in the atmosphere. For science lovers, this program can be used in reverse to simulate the sky environment on the surface through the atmospheric composition of celestial bodies.
This kind of simulation is still very interesting, and it can also help scientists to verify the correctness of theoretical analysis. If we successfully confirm the results of these simulations, it is very reasonable to explain that the predicted sky color of exoplanets has very high accuracy. At that time, even if we don't go to exoplanets, we can experience what it's like to land.