Image courtesy of National Solar Observatory, Sunspot, NM
As we discussed last time, the single most important factor for determining how much damage an impactor will cause is the size of the impactor. We can explore the effect that this has using the following interactive web site.
The table at the bottom of this web page gives reasonable guesses at the consequences that would result from impactors of various sizes.
The Sun is the most prominent feature of our solar system. If alien civilizations were studying our solar system from afar using the kind of technology we have on Earth today, they would only see the Sun, and perhaps a slight wobble of the Sun caused by Jupiter's gravity. The Earth would not be detectable.
The Sun contains 98% the mass of the entire solar system (think back to our lab where we built a scale model of the solar system -- what did you use to represent the Sun and the Earth? What about Jupiter?). It is also very LARGE compared to the planets. One could fit 1.3 MILLION Earths inside of the Sun. [One could fit 1400 Earths inside of Jupiter.]
Discussion: How is the Sun different from the planets? List as many ways as you can think of. How is the Sun similar to the planets? Again, list as many ways as you can think of.
Image courtesy of National Solar Observatory, Sunspot, NM
The Sun is composed of a LOT of hydrogen. By mass, its composition is 73% hydrogen, 25% helium, and 2% everything else. The Sun creates its own energy in its interior. This is done by the process known as nuclear fusion. This process requires extremely high temperatures such as those found in the Sun's interior. In this process, 4 protons (hydrogen nuclei) combine to form 1 helium nucleus. This reaction results in the release of energy, which then makes its way from the Sun's interior to the surface of the Sun.
The Sun's energy escapes through radiation and convection. When we look at the surface of the Sun, we can see the tops of the convective cells that carry energy from below. These are known as granules because at low resolution, the Sun's surface appears grainy. Here are some real-time movies of the solar granulation.