What does it mean when an emission line of helium from a galaxy is shifted toward red?(1 point)
The galaxy contains a small percent of hydrogen.
The galaxy contains a large percent of hydrogen.>>>
The galaxy is moving away from the viewer.
The galaxy is moving toward the viewer.
The galaxy is moving away from the viewer.
woah really! i have heard of the name Doppler effect but i never knew it was that
yo thanks that was really fast!!
That is known as the Doppler effect.
When an emission line of helium from a galaxy is shifted toward red, it means that the galaxy is moving away from the viewer. This phenomena is known as redshift.
To understand why this happens, we need to consider the concept of the Doppler effect. The Doppler effect is the change in frequency or wavelength of a wave as a result of the relative motion between the source of the wave and the observer. In the case of light, when an object is moving away from us, the wavelength of the light it emits appears longer, causing a shift toward the red end of the electromagnetic spectrum.
In the context of galaxies, the observed redshift indicates that they are moving away from us. This phenomenon is a key piece of evidence supporting the expanding universe theory, suggesting that most galaxies are moving away from each other due to the expansion of space.
To determine the redshift of a galaxy, astronomers measure the shift in the wavelength of specific spectral lines, such as those produced by helium. By comparing the observed wavelength of the emission line with the known rest wavelength, they can calculate the redshift and infer the galaxy's velocity and distance.
1) A
2) B
3) C
4) C
5) C, D