Since even before the dawn of civilization, the sun has been essential in farming, religion, and telling time. It's a star that's been worshipped and studied, and so to celebrate our 30th anniversary, correspondent Martha Teichner looks at the history of the sun, as well as a look forward to the future.
Some show-off, that sun. Performing its fire dance not just on Sunday, but every day, morning and night, the world over, for all of us Earthlings … rich and poor, old and young … no ticket required.
What exactly is the sun?
"It's a big ball of hydrogen gas," said Owen Gingerich, professor of astronomy and history of science emeritus, at the Harvard Smithsonian Center for Astrophysics.
Not so big. In fact, kind of middling for a star … but enormous compared to the Earth.
"It's one thing to say, well, the diameter of the sun is 100 times the diameter of the Earth," Gingerich told Teichner. "But you don't really get the impression of how big the sun really is unless you can see it in three dimensions."
How old is the sun? "About five billion years," said Gingerich, who assured us, "it's just about halfway through its lifetime."
It's really hot, maybe 28 million degrees Fahrenheit at its core, and it's burning up. There are nuclear reactions going on inside it all the time. When the energy works its way to the surface, we see it as sunshine..