According to foreign media reports, at sunset, the red and light red sky is a unique beauty on the earth. But what color is the sky at sunset for other planets in the solar system?
the answer depends on the planet. On Mars, for example, there is a blue glow at sunrise and sunset. On Uranus, the sky changes from blue to blue-green at sunset. On Titan, as the sun sinks below the horizon, the sky changes from yellow to orange to brown.
the color of the sky at sunset is different because these colors are largely the product of light scattered by particles in the atmospheres of the planets. Many people think that the formation mechanism of sunset color on Mars is the same as that on earth. But this is not the case.
the earth’s atmosphere is made up of tiny gas molecules, mostly nitrogen and oxygen. These gas molecules scatter blue and purple light more efficiently than red long wave light. This phenomenon of selective scattering of light by small molecules is called Rayleigh scattering. Because of this phenomenon, the sky on earth at noon is blue, but at sunrise and sunset, the sun’s path in the atmosphere is longer, so more blue light will be scattered along the way, and finally transmitted to our eyes are mostly red and yellow light with long wavelength, thus producing the bright color of floating light and gold at sunset.
any planet whose atmosphere is mainly composed of gases follows a similar pattern, with long wave light dominating at sunset. For example, hydrogen, helium and methane molecules in Uranus’s atmosphere will scatter blue and green short wave light, and most of the red long wave light will be absorbed and will not be re emitted. Therefore, the sky on Uranus is generally blue, but it will turn blue-green at sunset, because, like earth, a large amount of blue light will be scattered in the process of propagation, leaving behind Most of them are green light with short wavelength.
but if the main component of a planet’s atmosphere is not gas, the sunset on that planet will look very different. Take Mars. The density of gases in the Martian atmosphere is only about 80 times that on earth, so light on Mars is mainly scattered by larger dust molecules.
in 2014, a study was carried out using data collected by the courage Mars probe. It was found that the way in which dust scatters light on Mars is quite different from that of gas molecules. The blue sunset on Mars is caused by the rule that dust particles scatter light.
gas molecules scatter light in all directions, while dust particles scatter light mainly forward. In addition, the angle range of red light scattered by dust particles is much wider than that of blue light, so the blue light is more concentrated. The blue light on Mars is about five times as strong as the red light.
if you look at the sunset on Mars, you will see that the sun is also white, because light does not change color as it passes through Mars. But the sun is surrounded by a circle of blue light, and then the sky is more red, because the red light scattering angle is wider.
as for other planets and moons, we must fully understand their atmospheric composition, otherwise it is almost impossible to predict their sunset scenarios. However, if we know that the atmosphere of an object is mainly composed of gases, we can predict that the color of the object at sunset must be dominated by long wave light.
but if the atmosphere of a planet is mainly composed of other substances, it is hard to say. Different types and sizes of dust scatter light in different ways. In other words, if you think the sunset on earth is as beautiful as “exotic”, it’s better to put it another way, because such a sunset is actually a unique feature of a planet with a gaseous atmosphere like the earth, and it is not a “exotic” scene. Skip to content