In the laboratory, an atom emits a spectral line at a wavelength of 400 nanometers. In the spectrum of a star, the same spectral line is found to have a wavelength of 410 nanometers. What can be said about the star?

a. It is hotter than the Sun.
b. It is moving toward the Earth.
c. It is moving away from the Earth
d. It contains elements that are not found on Earth.

Use the same formula I mentioned in the question on a moving star.

In that formula, 'v' is considered positive when the object is moving away, and negative when moving closer.

It is hotter than the sun

To determine what can be said about the star based on the given information, we need to analyze the shift in spectral line wavelength.

The discrepancy in wavelength, with the star's spectral line measuring 410 nanometers compared to the laboratory measurement of 400 nanometers, indicates a shift towards longer wavelengths. This phenomenon is known as a redshift.

Based on this redshift, we can conclude that the star is moving away from the Earth. Therefore, the correct answer is c. It is moving away from the Earth.

To determine what can be said about the star, we need to analyze the difference in wavelengths between the laboratory atom and the star's spectrum.

The phenomenon responsible for the shift in wavelength is called the Doppler effect. When an object that emits light is moving relative to an observer, the wavelength of the light appears either shorter (blueshift) or longer (redshift) compared to when the object is at rest relative to the observer.

In this case, since the spectral line is observed at a longer wavelength in the star's spectrum (410 nanometers) compared to the laboratory (400 nanometers), it means there is a redshift. The redshift indicates that the star is moving away from the Earth.

Therefore, the correct answer is c. It is moving away from the Earth.