Question

To understand the interplay of observations and models you must first be able to distinguish between things that we observe and things that we infer from models. Consider the following statements about the Sun. Classify each statement as an observation or as an inference based on the current, accepted model for the Sun.
Observations
The photosphere is made mostly of hydrogen and helium
The photosphere emits mostly visible light.
The Corona is hotter than the photosphere.
The Sun emits neutrinos.
The sun generates energy by fusing hydrogen into helium in its core.
The core temperature is 10 million k
The convection zone is cooler than the radiation zone.
The composition of the photosphere is the same as that of the gas cloud that gave birth to our solar system.

Answer 1

Answer:

The photosphere is made mostly of hydrogen and helium (Observation)

The photosphere emits mostly visible light. (Observation)

The Corona is hotter than the photosphere. (Observation)

The Sun emits neutrinos. (Observation)

The sun generates energy by fusing hydrogen into helium in its core.(Inferred by the current sun model)

The core temperature is 10 million k (Inferred by the current sun model)

The convection zone is cooler than the radiation zone. (Inferred by the current sun model)

The composition of the photosphere is the same as that of the gas cloud that gave birth to our solar system. (Inferred by the current sun model)

Explanation:

The photosphere is made mostly of hydrogen and helium (Observation)

The spectrum of a star may give crucial information about some of its properties.

And it is said that a spectrum is the breakdown of light, coming from a star, in its characteristical colors (wavelengths).

In the case of stars, we get an absorption spectra in which the light of the innermost layers will be absorbed by the atoms in the photosphere, so the spectrum will have dark lines that correspond with the absorption.

An extensive study to the spectrum of the sun will determine the chemical composition of its surface.  

The photosphere emits mostly visible light. (Observation)

Stars behave locally as a blackbody. Blackbodies are objects that absorb all the radiation, and for that reason they are black. The spectrum of a star its similar to the spectrum of a blackbody, so Wien’s law can be used to estimate the effective temperature of the star.  

Wien’s law establish that the peak of emission will be in shorter wavelengths if the temperature is high and longer wavelengths for low temperatures.

In the solar spectrum it is possible to see that the peak of emission correspond to wavelengths that are in the visible range.

The Corona is hotter than the photosphere. (Observation).

Using the approach above it is possible to determine the temperature of the corona and the photosphere by means of its spectrum.

We can get the temperature replacing the peak of emission of the spectrum of the corona in equation 1.

$\lambda max = \frac{b}{T}$   (1)  

where λmax is the wavelength of the peak of emission, b is the Wien’s constant and T is the temperature.

the same procedure is followed for the photosphere temperature.

The Sun emits neutrinos. (Observation)

Different experiments have demonstrated the presence of neutrinos, as an example Super-Kamiokande (a neutrino observatory).

The sun generates energy by fusing hydrogen into helium in its core.(Inferred by the current sun model)

The only way to explain the energy production from the sun is assuming the mechanism of nuclear reaction.

The core temperature is 10 million k (Inferred by the current sun model)

It is got that the temperature in the core is 10 million k by solving the equation of state in a stellar structure model and giving boundary conditions to the sun case.

The convection zone is cooler than the radiation zone. (Inferred by the current sun model)

The stellar structure models infer it by solving the equations of energy transport.

The composition of the photosphere is the same as that of the gas cloud that gave birth to our solar system. (Inferred by the current sun model)

Theory said that stars were formed from a molecular cloud, so the chemical composition of birth stars must be share the chemical composition of the cloud.