Mindblown: a blog about philosophy.
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The Solar Cycle
Learning Objectives By the end of this section, you will be able to: Before the invention of the telescope, the Sun was thought to be an unchanging and perfect sphere. We now know that the Sun is in a perpetual state of change: its surface is a seething, bubbling cauldron of hot gas. Areas that are darker…
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The Structure and Composition of the Sun
Learning Objectives By the end of this section, you will be able to: The Sun, like all stars, is an enormous ball of extremely hot, largely ionized gas, shining under its own power. And we do mean enormous. The Sun could fit 109 Earths side-by-side across its diameter, and it has enough volume (takes up enough…
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Thinking Ahead
“Space weather” may sound like a contradiction. How can there be weather in the vacuum of space? Yet space weather, which refers to changing conditions in space, is an active field of research and can have profound effects on Earth. We are all familiar with the ups and downs of weather on Earth, and how…
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Planetary Evolution
Learning Objectives By the end of this section, you will be able to: While we await more discoveries and better understanding of other planetary systems, let us look again at the early history of our own solar system, after the dissipation of our dust disk. The era of giant impacts was probably confined to the…
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Comparison with Other Planetary Systems
Learning Objectives By the end of this section, you will be able to: Until the middle 1990s, the practical study of the origin of planets focused on our single known example—the solar system. Although there had been a great deal of speculation about planets circling other stars, none had actually been detected. Logically enough, in…
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Formation of the Solar System
Learning Objectives By the end of this section, you will be able to: As we have seen, the comets, asteroids, and meteorites are surviving remnants from the processes that formed the solar system. The planets, moons, and the Sun, of course, also are the products of the formation process, although the material in them has undergone a…
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Meteorites: Stones from Heaven
Learning Objectives By the end of this section, you will be able to: Any fragment of interplanetary debris that survives its fiery plunge through Earth’s atmosphere is called a meteorite. Meteorites fall only very rarely in any one locality, but over the entire Earth thousands fall each year. Some meteorites are loners, but many are…
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Meteors
Learning Objectives By the end of this section, you will be able to: As we saw in Comets and Asteroids: Debris of the Solar System, the ices in comets evaporate when they get close to the Sun, together spraying millions of tons of rock and dust into the inner solar system. There is also dust from…
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Thinking Ahead
Imagine you are a scientist examining a sample of rock that had fallen from space a few days earlier and you find within it some of the chemical building blocks of life. How could you determine whether those “organic” materials came from space or were merely the result of earthly contamination? We conclude our survey…
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The Origin and Fate of Comets and Related Objects
Learning Objectives By the end of this section, you will be able to: The comets we notice when they come near Earth (especially the ones coming for the first time) are probably the most primitive objects we can study, preserved unchanged for billions of years in the deep freeze of the outer solar system. However,…
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