Our present theory of the Sun's internal structure is in some significant way based on our knowledge of:

a. the oldest biological growth records on earth being used to determine the constancy of the Sun’s luminosity over the largest part of its’ prior main sequence lifetime.
b. the fact that Jupiter has a composition thought to be identical to the Sun's.
c. the length of time it takes the Jupiter to orbit once around the sun to determine the Sun’s angular momentum.
d. the spectrum of the light coming from the Sun to determine the details of the Sun’s composition at its outer surface.
e. the period and semi-major axis of the earth's orbit to determine the Sun’s mass.

People with normal vision cannot focus their eyes underwater if they aren't wearing a face mask or goggles and there is water in contact with their eyes. in a simplified model of the human eye, the aqueous and vitreous humors and the lens all have a refractive index of 1.40, and all the refraction occurs at the cornea, whose vertex is 2.60 cm from the retina.with the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 2.05cm in front of the eye.)