I think the 5 million km figure is just an order-of-magnitude/ballpark estimate, not something precise. "The corona starts at 10,000 kilometers and extends out

I think the 5 million km figure is just an order-of-magnitude/ballpark estimate, not something precise. "The corona starts at 10,000 kilometers and extends out to about 10 million kilometers, where the gas finally escapes the sun's gravity and becomes part of the solar wind." [1] [1] https://www.scientificamerican.com/article/i-read-that-the-suns-surf/ https://www.scientificamerican.com/article/i-read-that-the-s...