Double Solar Eclipse? What Does This Mean!


Today, Bad Astronomy linked to this picture by Thierry Legault. Not only is it gorgeous, but it’s a bit special. Why? It’s a friggin’ double eclipse! Wait, wut you ask? Phil Plait over at the aforementioned site breaks it down in ways that I can only fathom.

Can you see why he traveled so far to get this shot? The silhouette of the Moon taking a dark bite out of the Sun is obvious enough, as are some interesting sunspots on the Sun’s face… but wait a sec… that one spot isn’t a spot at all, it’s the International Space Station! This was a  double eclipse!

That’s why Thierry sojourned to Oman; due to the geometry of the ISS orbit, it was from there that he had the best chance of getting a picture of the station as it passed in front of the Sun during the relatively brief duration of the actual solar eclipse. But talk about brief; the ISS was in front of the Sun for less than second, so not only did he have one chance at getting this spectacular once-in-a-lifetime shot, but he had only a fraction of a second to snap it!

To give you an overall idea of what you’re seeing here: the Sun is 147 million kilometers away (less than usual because this eclipse happened, coincidentally,  very close to perihelion, when Earth was closest to the Sun). The Moon is 390,000 kilometers away. The Sun is about 400 times bigger than the Moon, but also about 400 times farther away, making them look about the same size in the sky. If you’re still having a hard time picturing the scale, take a look at the dark sunspot in the lower right of the big picture:  it’s about twice the size of the Earth!

Like I said, Plait is amazing. This image is already incredible, but then he goes and gives it even more scope. The dark sunspot is twice the size of Earth? Incredible. In the truest sense of the word.