A growing number of researchers think that the sun is actually larger than commonly thought.
Scientists don’t know the sun’s size as precisely as the details of the Earth and moon, making it a sticking point for perplexed eclipse modelers.
Xavier Jubier creates detailed models of solar and lunar eclipses that work with Google Maps to show precisely where the shadow of the sun will fall on the Earth, and what the eclipse will look like at each point. He came to realize there was something off about the sun’s measurements as he matched his eclipse simulations with actual photos. The photos helped him identify exactly where an observer had been for historical eclipses — but those precise eclipse shapes only made sense if he scaled up the sun’s radius by a few hundred kilometers. [Total Solar Eclipse 2017: When, Where and How to See It (Safely)]
“For me, something was wrong somewhere, but that’s all I could say,” Jubier told Space.com.
Scientists’ knowledge of the Earth’s and moon’s contours weren’t exact enough to highlight this discrepancy until about 10 years ago — the same time that modern eclipse simulations became possible through computer power and precision mapping. So it was around then that Jubier began to realize something was amiss.
NASA researcher Ernie Wright came to a similar conclusion as he began to create increasingly precise models of solar eclipses, starting about two years ago. He, too, had to scale up the sun slightly from the traditional size for his calculations to match reality.
“How can you not know this?” Wright recalls thinking. “You just hold a ruler up to the sky, and you say it’s this big.”
But as it turns out, it’s not that simple, Wright told Space.com.