Anticipating the solar eclipse on August 21, let’s consider the sun.
The sun is of moderate age, 4.6 billion years – coalescing as a star from dust and gas when the universe was about 2/3rds of its present age. It was originally far larger than it now is, but the inward gravitational pull of the dust and gas squeezed together to the point that the sun’s interior is 8 times the density of gold. It cooks along at an interior temperature of roughly 28,000,000 degrees Fahrenheit, and a pressure of 250 billion times earth’s atmospheric pressure, just right for nuclear fusion.
It is expected that for the next 5 billion years the sun will continue to generate energy by converting four protons (hydrogen nuclei) into a single helium nucleus, which, being slightly lighter than the four protons, releases the small difference as energy. That energy release is equivalent every second to the energy of 100 billion one-megaton nuclear bombs. After that we can expect things to change. In the end the sun will turn into a red giant, and we had better have someplace else to go, because it will grow so large that it will consume the inner planets, probably including the earth. But it may warm the moons of Jupiter quite nicely, giving us another opportunity to do things right.
For now the sun is about right for life here in Vermont. If you want to see it disappear for about 3 minutes this month, consider traveling to Salem, Oregon, where at 10:20 AM PDT it will start its overland course from NW to SE, reaching the Atlantic just north of Charleston in South Carolina at 2:48 PM EDT.
Yours From The Field,