Venus is the closest planet to Earth in the solar system and the planet most Earth-like. Its diameter, mass, and density are all quite close to the Earth, so it is sometimes referred to as the "sister star of the Earth". However, the environment of Venus is very different from that of Earth, it is a "hell planet" with high temperature, high pressure, no water, and no oxygen. The surface temperature of Venus is as high as 460 degrees Celsius, which is enough to melt lead;The atmospheric pressure of Venus is 90 times that of Earth, which is equivalent to the water pressure in the deep ocean;Venus's atmosphere is mostly made up of carbon dioxide, which causes a strong greenhouse effect;Venus's clouds are made up of sulfuric acid droplets, which obscure the surface of Venus, making it impenetrable to visible light.
Despite the difficulties of exploration of Venus, scientists have not given up on the study and exploration of the planet. They use telescopes on the ground and in orbit, as well as technologies such as radar and infrared that can penetrate clouds, to constantly unravel the mysteries of Venus. They discovered many interesting phenomena such as Venus's topography, climate, atmospheric circulation, magnetic field, volcanic activity, etc., and also put forward many hypotheses about the origin, evolution and future of Venus.
In all these studies and explorations, there is one question that has been bothering scientists: what are the clouds of Venus made of?Scientists know that Venus's clouds are mainly made up of sulfuric acid droplets, which also contain some elements such as water, chlorine and iron. The concentration of these elements varies with the height of Venus's thick and hostile atmosphere. However, until now, they have not been able to determine what the missing components are that are capable of explaining the patches and streaks in the clouds of Venus that are only visible in the ultraviolet range.
In a new study published in the journal Science Advances, researchers at the University of Cambridge have come up with a possible answer. They synthesized a number of iron-containing sulfate minerals that were stable under harsh chemical conditions in the clouds of Venus, and using spectroscopic analysis, they found a combination of two minerals, siderite and acidic iron sulfate, that could explain the mysterious ultraviolet absorption signatures on our neighboring planets.
The ultraviolet absorption characteristic in Venus's clouds refers to the fact that when we look at Venus with ultraviolet light, we will find that Venus's clouds exhibit a specific pattern, that is, there are some dark patches and streaks in the clouds, rather than uniform bright colors. These dark patches and streaks change at different times and locations, suggesting that they are related to Venus's atmospheric circulation.
The feature of Venusian clouds is a mystery because scientists don't know what the ingredients that cause this feature are. They know that Venus's clouds are mostly made up of sulfuric acid droplets, but the sulfuric acid droplets themselves do not absorb ultraviolet light, but rather reflect ultraviolet light, giving the clouds a bright color. Therefore, there must be some other component present in the clouds to create dark patches and streaks.
And Venus clouds are hard to find because they are very low in content and can interact with other components to form complex chemical reactions. The chemical environment in the clouds of Venus is very harsh, with high temperature, high pressure, high acidity, high oxidation, etc., which makes it impossible for many common compounds to exist stably here. Therefore, it is very difficult to find an ingredient that can both be stable here and absorb ultraviolet rays.
Iron-containing sulfate minerals are a class of inorganic minerals that contain iron and sulfate, which are usually yellow or brown in color and sometimes green or blue. Iron-containing sulfate minerals are some of the common secondary minerals on Earth that are usually formed during weathering, oxidation, or hydrolysis of iron-bearing minerals.
Iron-bearing sulfate minerals may be missing components in the Venusian clouds because they have special properties that allow them to survive in the harsh conditions of the Venusian clouds and to absorb ultraviolet light.
Iron-bearing sulfate minerals are able to survive stably under harsh conditions in the clouds of Venus because of their chemical structure that can adapt to high temperatures, high pressures, high acidity, high oxidation, etc. Iron ions in iron-bearing sulfate minerals can transition between different oxidation states, which regulates the stability and solubility of the mineral. For example, siderite loses its crystalline water at high temperatures and turns into anhydrite, which turns into acidic iron sulfate at high acidity. These changes allow iron-bearing sulfate minerals to remain stable at different atmospheric altitudes.
Iron-bearing sulfate minerals are able to absorb ultraviolet light because the iron ions in them can transition between different oxidation states, resulting in different electronic transitions, resulting in different spectral signatures. For example, the divalent iron ions in siderite can be excited by ultraviolet light and turn into ferric ions, which absorb ultraviolet light. The ferric ions in acid iron sulfate can form complexes with sulfate ions, thereby increasing the intensity and range of ultraviolet absorption.
The combination of iron-bearing sulfate minerals can explain the UV absorption characteristics in Venusian clouds because their absorption patterns and degrees are consistent with the dark ultraviolet plaques observed in Venusian clouds. According to the results of experiments by researchers at the University of Cambridge, a mixture of siderite and acidic iron sulfate is able to produce different absorption intensities at different wavelengths, resulting in spectral signatures that match the patches and streaks in the clouds of Venus. The combination of these minerals is also able to reflect chemical and physical changes in Venusian clouds, explaining the dynamics of patches and streaks.
The significance of the iron-containing sulfate minerals in Venus's clouds is manifold, and they not only solve a long-standing mystery in Venus's clouds, but also reveal the intricate chemical networks in Venus's atmosphere, as well as the elemental cycles on Venus' surface.
The iron-containing sulfate minerals in Venus's clouds have solved a long-standing mystery in Venus's clouds, namely the origin of ultraviolet absorption characteristics in Venus's clouds. Since its discovery in the 1960s, this feature has been a difficult problem for scientists to explore Venus, as it is related to Venus's cloud composition, atmospheric circulation, climate change, and more. By discovering that iron-bearing sulfate minerals may be the missing ingredient responsible for this feature, we can better understand the physical and chemical properties of Venus's clouds, as well as their interaction with solar radiation.
The iron-containing sulfate minerals in Venus's clouds reveal for us the intricate chemical network in Venus's atmosphere, where the various elements and compounds in Venus's atmosphere transform and balance with each other. The chemical reactions in the atmosphere of Venus are very complex, involving carbon dioxide, water, sulfur, chlorine, nitrogen, oxygen, hydrogen and other elements and compounds, which will undergo various changes under different temperature, pressure, acidity, oxidation and other conditions, thus affecting the atmospheric composition, cloud structure, greenhouse effect, wind speed and so on. By discovering that iron-bearing sulfate minerals may be an important chemical component in Venus's clouds, we can better understand these chemical reactions in Venus's atmosphere, as well as their relationship to Venus' climate and environment.
The iron-containing sulfate minerals in the clouds of Venus reveal for us the elemental cycle on the surface of Venus, i.e., how the various elements on the surface of Venus are transported and exchanged through the atmosphere and clouds. The elemental cycle on the surface of Venus is a very important geochemical process that reflects the internal activity, surface morphology, volcanic eruptions, plate movements, etc. By discovering that iron-bearing sulfate minerals may be an iron-bearing mineral in the clouds of Venus, we can speculate that there may be iron-bearing minerals or rocks on the surface of Venus, which may transport iron elements into the atmosphere and clouds through volcanic eruptions or weathering processes, thus forming iron-containing sulfate minerals. These minerals may also be re-transported to the surface through rainfall or sedimentation, creating a closed elemental cycle.
In the future, scientists will use more advanced technology and equipment to conduct more in-depth research and analysis of iron-containing sulfate minerals in the clouds of Venus, and analyze the exact content, distribution and morphology of iron-containing sulfate minerals in the clouds of Venus, as well as their interactions and influences with other components, as well as the mechanism and process of the formation and change of iron-containing sulfate minerals, and their relationship with the atmospheric circulation, climate change, and solar activity of Venus.