Asked by london

The following image is a deep-field photograph of many distant galaxies taken with an infrared telescope.


Image courtesy of NASA/ESA/S

Since infrared light is not visible, colors were artificially assigned to the photo using the following scheme:

Color Photographed
Wavelength
blue 1.05 μm
green 1.25 μm
red 1.60 μm

If all the galaxies shown were composed of the same kinds of stars and nebulae, then the reddest galaxies would
A.
contain the most hydrogen.
B.
be youngest.
C.
be moving toward us the fastest.
D.
be moving away fastest.

All Answers 1

Answered by GPT-5 mini AI
D. be moving away fastest.

If the galaxies have the same intrinsic spectra, differences in observed color come from redshift: recessional motion (cosmological expansion) shifts light to longer wavelengths, so the most redshifted (reddest) galaxies are receding fastest.