The most volcanic celestial body in the solar system, sulfur dioxide is ejected in large quantities, poisoning the atmosphere

On the earth, as the plate movement continues, the landform of volcanoes is formed. In the weakest part of the earth's crust, hot magma will spurt out, bringing huge disasters to the living things on earth.

Volcanoes are indeed scary, but we should also be thankful that we live on Earth, not Io. As the planet with the most volcanic activity in the solar system, every day on Io is spent in fear.

On this satellite with a diameter of 3642 kilometers, there are more than 400 active volcanoes dotted around. Unlike Earth's volcanoes, which arise from plate movement, volcanoes on Io come from tidal forces. While being subjected to the gravity of Jupiter, it also bears the gravitational restraint of the other three huge satellites, which causes the internal materials to churn and rub continuously, maintain high temperature and also have a lot of energy, and finally some of them are formed by volcanoes. Form releases energy.

While ejecting magma, Io's volcanoes also emit large amounts of sulfur dioxide. They are ejected in gaseous form, but freeze solid at nighttime temperatures and coat the moon's surface. Therefore, the moon Io we see always appears waxy yellow like a sick person.

So here comes the question: How much of the sulfur dioxide in the atmosphere of Io comes from volcanoes, and how much of the solid sulfur dioxide on the surface returns to the atmosphere after being sublimated by heat? Scientists have never had an accurate answer to this question.

Imke de Pater, an astronomer at the University of California, Berkeley, introduced the problem: "Exactly which process is driving the changes in Io's atmosphere is still unknown. Whether it is volcanic activity, or when Io is bathed in sunlight. What about the sublimation gas from the surface ice?"

Although hundreds of volcanoes release sulfur dioxide and other gases in turn, the atmosphere on the surface of Io is still very thin, and the pressure is only one billionth of that of the earth. A large part of the reason is Jupiter. Studies have shown that a large amount of gas on Io escapes under the action of Jupiter, and almost 1 ton of gas escapes every second, forming a ring structure between Io and Jupiter, which is called Io Plasma circulation.

Although the remaining gas is not much, it can still provide us with a lot of information. Through the study of these gases, scientists can speculate on the possible internal structural geological processes of Io, and even help us understand similar processes in exoplanets. In addition, there are other celestial bodies in the universe that suffer gravitational tug-of-war like Io, but they do not produce the same effect. The reason for this also requires us to have a thorough understanding of the mechanism of Io's atmosphere. Can.

To solve these mysteries, astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to observe Io at radio wavelengths, using it to enter and leave Jupiter's shadow (also known as Jupiter's shadow). Wei Yi’s evening and dawn) to analyze the questions they have been curious about for a long time.

They first discovered that after Io enters the dark night, the temperature will drop below the freezing point of sulfur dioxide, causing it to condense and seal on the surface.

When daylight returns on Io, the frozen sulfur dioxide sublimates into the atmosphere. To their surprise, the process took only 10 minutes, much faster than expected. And this magical phenomenon is an important tool for studying the impact of Io volcanoes on the atmosphere.

Statia Luszcz-Cook, an astronomer at Columbia University, said: "When Io entered the shadow of Jupiter and out of direct sunlight, the temperature was too low for sulfur dioxide, which condensed on Io. Surface. During this period, we can only see sulfur dioxide from the volcano.” As the sulfur dioxide in the air has completely condensed, the appearance of this substance in Io’s atmosphere during this period must have come from volcanic eruptions. This is an excellent opportunity to study volcanic contributions to Io's sulfur dioxide.

With ALMA's powerful observation capabilities, the research team clearly distinguished the plumes of sulfur dioxide and sulfur monoxide on Io for the first time. They proved that sulfur dioxide released by volcanoes does play an important role in Io's atmosphere. Based on these images, they speculate that about 30%-50% of the sulfur dioxide in Io's atmosphere comes from volcanoes. Admittedly, this does not account for the vast majority, but for volcanoes, this data is quite amazing.

At the same time, in areas without sulfur dioxide and sulfur monoxide, the researchers also found another substance, potassium chloride in volcanic eruptions. This suggests that the magma systems beneath Io are not perfectly connected, or they should be ejecting similar material. This hints us that there is more complexity beneath the surface of Io than we thought.

In the next step, the research team plans to measure the temperature on the surface of Io, which will be of great help in further narrowing down the proportion of sulfur dioxide emitted by volcanoes. It's not an easy job, especially with temperature measurements at low altitudes on Io, but the team thinks they can do it.

"To detect Io's temperature, we need to have a higher resolution, which requires us to observe the satellite for a longer period of time," de Pater said. "We can only do this when Io is in sunlight." , because it is not in the shadow for a long time. During such observations, Io will have a revolution angle of 10°. We need to use software to produce unobstructed images, which we This has been done before with ALMA and the Very Large Telescope when taking radio images of Jupiter."

As the most volcanically active body in the solar system, the internal structure of Io has always been one of the most curious questions for scientists. This is a supplement to our understanding of the internal structure of the earth. Only by understanding the structure of various rocky planets can we say that we really understand all the internal mechanisms of the earth. For some problems that cannot be solved on the earth, we can only resort to other celestial bodies in the solar system, or even more distant exoplanets. Perhaps in the most distant places, there are the most recent secrets.