This article originally appeared on Conversation. The publication posted the article on Space.com. Expert Voices: Commentary and Insights…
Martin Gerard Connors, Professor of Space Science and Physics, University of Athabasca
Recent advances in astronomy allow us to observe that planets orbiting other stars have weather. Indeed, we knew that on other planets in our solar system the weather is in many cases more severe than ours.
Our lives are affected by short-term atmospheric fluctuations in the weather on Earth, and we fear that longer-term climate change will also have a big impact. The recently coined term “space weather” refers to effects that occur in space, but affect the Earth and the regions around it. Space weather, more subtle than meteorological weather, typically affects technological systems and has potential impacts that range from communications disruptions to power outages.
Read more: Sunny weather has a real material impact on the Earth.
The ability to predict space weather is an important tool in providing warnings so that one can try to mitigate it and hopefully prevent a catastrophe in extreme cases.
Weather forecasting history
We are now used to large-scale weather forecasts, which are fairly accurate on a roughly two-week timescale.
Scientific weather forecasting began about a century ago, and the term “front” was associated with the First World War. Weather forecasts are based on a good knowledge of basic theory, systematized in huge computer programs running on the most modern computers, with huge amounts of input data.
Important weather parameters such as moisture content can be measured using satellites that continuously monitor. Other measurements are also easily accomplished, such as with nearly 2,000 meteorological balloons launched every day. The study of the limitations of weather forecasting led to the emergence of chaos theory, sometimes referred to as the “butterfly effect.” The accumulation of errors leads to a practical limit of two weeks.
In contrast, space weather prediction is only truly reliable in about an hour!
Most of space weather comes from the sun. Its outer atmosphere is blown into space at supersonic speed, albeit at such a low density that interplanetary space is more rarefied than what our laboratories consider to be a vacuum. Unlike terrestrial winds, this solar wind carries a magnetic field. This is much smaller than the Earth’s own field, which we can detect with a compass on the surface, and much smaller than the field next to the refrigerator magnet, but it can interact with the Earth, playing an important role in space weather.
A very thin solar wind with a very weak magnetic field, however, can partially affect the Earth, because it interacts with a large magnetic bubble around the Earth, called the magnetosphere, over a very large area, at least a hundred times larger than the surface. our planet. Just as a wind that can barely move a filament can move a huge sailing ship when hooked on large sails, the effect of the solar wind through its direct pressure (such as on a sail) or through its magnetic field interacting with the earth can be huge.
As a starting point, the Sun itself is a seething mass of hot gas and magnetic fields, and their interactions are complex, sometimes even explosive. Magnetic fields concentrate around sunspots and cause electromagnetic phenomena such as solar flares (the name speaks for itself) and coronal mass ejections. As with tornadoes on Earth, we usually know when conditions are favorable for these localized explosions, but accurate prediction is difficult.
Even after the event is detected, if a large mass of fast, hot and dense gas shoots in our direction (and such a “cloud”, in turn, is difficult to detect, coming at us against bright sunlight), another factor arises that complicates forecast of its danger.
Detecting magnetic fields
In contrast to the detectable, sometimes even visible, water content in the atmosphere, which is so important for meteorology, the magnetic field of gas emitted by the sun, including in hot and denser clouds as a result of explosions, is almost impossible to detect from afar. The effect of an interplanetary cloud is greatly enhanced if the direction of its magnetic field is opposite to the Earth’s own field, where it collides with the barrier of the Earth’s magnetosphere. In this case, a process known as “reunification” allows most of the cloud’s energy to be transferred to the area near the Earth and accumulates mainly on the night side, despite the fact that the cloud hits the side facing the Sun.
Through secondary processes, usually associated with further reconnection, this energy causes the effects of space weather. The Earth’s radiation belts can be highly charged, endangering astronauts and even satellites. These processes can also cause bright auroras, the beauty of which masks danger as they in turn create magnetic fields. The generator effect occurs when dancing auroras change magnetic fields, but unlike generators, which generate most of our electricity, the electric fields of the aurora are out of control.
Electric fields from auroras are small and undetectable by human senses. However, over a very large area, they can accumulate to apply significant stress. It is this effect that poses a threat to our largest infrastructure, such as power grids. To predict when this might happen, we need to measure from afar the size and direction of the magnetic field in the approaching cosmic cloud. However, this invisible field is invisible and difficult to detect until it gets close to us.
According to the laws of gravity of orbits, a satellite that continuously monitors magnetic fields by direct measurements should be about 1 million miles (1.6 million kilometers) from the Earth, a hundred times further between us and the Sun. A magnetic cloud, causing minor effects of space weather, usually takes about three days to travel from the Sun to Earth. A truly dangerous cloud from a larger solar explosion can take as little as a day. Because our observation satellites are relatively close to Earth, we know the critical direction of the magnetic field no more than an hour before collision. There is not much time right now to prepare vulnerable infrastructure such as power grids, communications and satellites for better survival.
Since the fleet of satellites needed for better warning is not even on blueprints, we must rely on luck in the face of space weather. It may come as little consolation that the approaching solar maximum – when the Sun’s surface is most active during a cycle and is expected to peak in 2025 – is projected to be moderate.
Mark Twain may have said that “it is difficult to make predictions, especially for the future,” but this is certainly true in the case of space weather.
This article is reprinted from The Conversation under a Creative Commons license. Read the original article.
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