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Something I just realized while reading this article is that the Earth is only about 100 solar diameters from the Sun. This was completely out of proportion wit

Something I just realized while reading this article is that the Earth is only about 100 solar diameters from the Sun. This was completely out of proportion with my gut feel. Edit: change "radii" to "diameters"

ljcn 7y ago
About 200 actually (you mistook the diameter for the radius). https://www.wolframalpha.com/input/?i=1+au+%2F+radius+of+the+sun https://www.wolframalpha.com/input/?i=1+au+%2F+radius+of+the...
- OnACoffeeBreak 7y ago
  Yes, you are correct. I meant diameters.
DonaldFisk 7y ago
I presume you mean diameters, not radii. Solar radius = 700000km Mean distance of Earth from sun = 1AU = 1.5e8 km = 214.3 solar radii. From Earth, solar radius = 0.25 degrees. 233 solar radii in 1 radian.
- OnACoffeeBreak 7y ago
  Yep, I meant to write diameters. > From Earth, solar radius = 0.25 degrees. 233 solar radii in 1 radian. I don't understand this. I think I understand that the sun would take up 0.5 degrees of the "view" (I don't have a good word for this) when looked at from Earth, so radius is 0.25 degrees. But how does the second statement follow? I get that a radian is about 57.3 degrees, so 57.3 / 0.25 = 230, but why why does 1 radian make sense to use here?
  - iclelland 7y ago
    An arc that spans one radian of a circle's circumference has the same length as the radius. So if you imagine a connected line of 233 suns across the sky, spanning 57.3 degrees, the actual length of that line would be the same as the distance from your eyes to the sun.
waynecochran 7y ago
If our sun was replaced by Betelgeuse, the earth would be inside the star: sun diameter = 1.3927 million km Betelgeuse diameter = 1.234 billion km Betelgeuse diameter / sun diameter = 886 > 100 The size of these stars is beyond mind boggling.
T-hawk 7y ago
Similarly, the Moon is about 100 lunar diameters from the Earth. Hence the moon and sun look the same size in the sky, and both total and annular eclipses can happen.

ljcn 7y ago

About 200 actually (you mistook the diameter for the radius). https://www.wolframalpha.com/input/?i=1+au+%2F+radius+of+the+sun https://www.wolframalpha.com/input/?i=1+au+%2F+radius+of+the...

OnACoffeeBreak 7y ago
Yes, you are correct. I meant diameters.

DonaldFisk 7y ago

I presume you mean diameters, not radii. Solar radius = 700000km Mean distance of Earth from sun = 1AU = 1.5e8 km = 214.3 solar radii. From Earth, solar radius = 0.25 degrees. 233 solar radii in 1 radian.

OnACoffeeBreak 7y ago
Yep, I meant to write diameters. > From Earth, solar radius = 0.25 degrees. 233 solar radii in 1 radian. I don't understand this. I think I understand that the sun would take up 0.5 degrees of the "view" (I don't have a good word for this) when looked at from Earth, so radius is 0.25 degrees. But how does the second statement follow? I get that a radian is about 57.3 degrees, so 57.3 / 0.25 = 230, but why why does 1 radian make sense to use here?
- iclelland 7y ago
  An arc that spans one radian of a circle's circumference has the same length as the radius. So if you imagine a connected line of 233 suns across the sky, spanning 57.3 degrees, the actual length of that line would be the same as the distance from your eyes to the sun.

waynecochran 7y ago

If our sun was replaced by Betelgeuse, the earth would be inside the star: sun diameter = 1.3927 million km Betelgeuse diameter = 1.234 billion km Betelgeuse diameter / sun diameter = 886 > 100 The size of these stars is beyond mind boggling.

T-hawk 7y ago

Similarly, the Moon is about 100 lunar diameters from the Earth. Hence the moon and sun look the same size in the sky, and both total and annular eclipses can happen.