Over the course of time the Sun's spectral analysis will gave a stronger Helium and weaker Hydrogen reading. Explain why this will happen.
mattbrady's answer is correct.
The Sun is a yellow main-sequence star near the middle of its life, so it is currently in the process of converting hydrogen into helium by fusion. In several billion years it will run out of hydrogen; when that happens, it will expand dramatically into a red giant (most likely engulfing all the inner planets, including Earth), and begin to fuse helium into carbon.
Well before that, however, the Sun will partially deplete its hydrogen reserves. If astronomers took precise enough spectral measurements over a long enough period of time (unlikely, but impossible---if we can measure gravity waves, we might just be able to do this), they would observe very subtle changes in which the quantity of hydrogen detected slightly decreased and the quantity of helium detected slightly increased. Within a human lifetime or even the lifetime of a civilization, this effect would be very small---about one one-millionth of the Sun's total hydrogen has been used up from the time when humans invented agriculture to today. But we might just be able to pick it up if our instruments were sensitive enough.
The Sun is the star at the center of our Solar System. Like many stars, our Sun is primarily made up of hydrogen atoms. The gravity of our Sun is incredibly stronger than Earth's due to its immense mass. In fact, the Sun's gravity is so strong that it pushes atoms together with enough force to cause the atoms to fuse together. It is these same hydrogen atoms that make up our Sun which are being fused together into helium.
The amount of hydrogen in the Sun is constantly decreasing as the nuclear fusion turns hydrogen into helium. This means that the helium that is constantly being created from the Sun's nuclear fusion will continue to rise.
Spectral analysis is a method used to study the origin of any spectrum of light. In particular, astronomical spectroscopy is used to determine the composition of a star by analyzing its spectrum.
Different atoms vibrate at different atomic frequencies and a spectral analysis will show this as distinct dark lines present on the spectrum of visible light (see image below of our Sun's spectral absorption lines). These lines are dark because the atoms in the Sun's outermost layer are absorbing discrete wavelengths of light corresponding to their atomic vibration. Hydrogen and helium each have their own unique spectral line and as the Sun ages the intensity of these absorption lines will decrease and increase respectively.