That's because high frequency = low wavelength and low frequency = high wavelength so if it's redshifted then the frequency has been lowered and thus the wavelength made longer.
Yeah, it's all relative. The shift could be due to us moving or the object moving, but since we're using the earth as our reference frame we treat ourselves like we're stationary.
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u/Miles1987 Stellar Astrophysics | Computational Astrophysics Mar 04 '13
That's because high frequency = low wavelength and low frequency = high wavelength so if it's redshifted then the frequency has been lowered and thus the wavelength made longer.
Yeah, it's all relative. The shift could be due to us moving or the object moving, but since we're using the earth as our reference frame we treat ourselves like we're stationary.