# How many degrees of arc is the width of the solar disk in Mercury's sky? Could you see solar flares (with protection) without lenses?

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• 2 months ago
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mercury:

Aphelion 69,816,900 kmPerihelion 46,001,200 km

Mean radius 2,439.7 km

SunMean radius 696,392 km

mean distance mercury to sun is average of Aphelion and Perihelion

which is about (69.8+46)/2 = 57.9e6 km

need to subtract radius of mercury to get surface distance to sun

57.9e6 km – 2000 km = 57.9e6 km

so the sun subtends 696e3 km at a distance of 57.9e6 km

using trig, half the angle = arctan (696e3/(0.5)57.9e6)) = 1.38º

twice that is 2.75º

as to visibility, some are visible on earth to the naked eye, so certainly even more would be visible on mercury.

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• 2 months ago

2.5 times as seen from Earth. The Sun's width is an average of 30 seconds of SRC, so 3.5 time would be 1.5° degrees of adv. 1° = 60 minutes.

I used the AVERAGE diameter of the Sun. The Sun can be 34' wide from Earth because the distance of Earth from the Sun varies by 5 million kilometers, 3.8 million miles.

No, you would NOT be able to see solar flares without lenses or filters.

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