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Let's talk about the rarity of our Earth and how special it is.

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How about how it is protected from the dangers of the space, unlike other celestial objects

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– the meteors, asteroids, and others.

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Although space is full of them, and our Earth can get hit, this happens very rarely, especially

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on levels that could be dangerous.

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We only hear news of close calls.

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Can you tell us about the way our planet is protected?

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The atmosphere, the Van Allen Belt, does our solar system have a protection too?

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Are we located in a protected part of the galaxy?

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A very interesting topic is the situation, the placement of the Earth in the context

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that it is.

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So the Earth is part of our solar system, the solar system is part of our galaxy, and we

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can ask the question, is the Earth occupying a special place?

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Is it well protected, for example?

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The first thing to point out is that in our galaxy, at the galactic scale, there are very

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strong physical effects, for example supernovae, that are occurring.

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When a supernova occurs, a massive star explodes, and its energy output briefly matches the energy

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output of the entire galaxy.

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Now the entire galaxy is 100 billion stars, so it's 100 billion times its normal energy

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output.

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As such, when that occurs, for many, many light years around it, any possibility of life would

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be sterilized.

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There would be no possibility of life.

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So, and even much farther distances, as these supernovae are going off, there is these galactic

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cosmic rays that are a source of potential harm to the Earth.

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But our solar system has essentially a magnetic field that is protecting it.

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And in particular, there is a solar wind, which is this radiation from the sun, that modulates

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or moderates the effect of these galactic cosmic rays.

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The solar wind, in that sense, is helpful.

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But in another sense, the same thing that the processes that give us the solar wind give

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us sometimes dangerous events, like coronal mass ejections, where the sun occasionally has

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a big output, then how do we get protected from that?

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It turns out, if you look at Venus, Venus is getting, was essentially destroyed as a

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habitable planet by the sterilization or stripping of the hydrogen from its atmosphere.

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And so all that is now there is carbon dioxide.

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At the temperature in the surface of Venus, it's much hotter than your ordinary oven.

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So that's why nobody sends spacecraft there, because your electronics will melt after a little

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while in Venus.

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It's very difficult.

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Earth is not like that.

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What's going on?

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Earth has a magnetosphere.

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There is a molten liquid iron core that's spinning inside the Earth.

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And the dynamo process essentially generates a magnetic field.

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And the magnetic field then modulates and moderates the effect of solar radiation, the solar particle

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radiation.

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So the Earth is, on the one hand, protected from galactic cosmic rays by the sun, and then

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it is protected from the sun by its own magnetosphere.

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And so there is this layer after layer of protection for the Earth, just from the standpoint

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of particle radiation.

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There's also very interesting things going on in this that I could go on, but I think this

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part expresses just the levels of protection that the Earth has.