1 Many people find that boxes with a 1.25 or 1 1/8 hole restrictor on them before an egg is laid are not utilized, even by smaller birds like titmice and chickadees. 2  If the entrance hole is enlarged (e.g., by woodpeckers or chewing rodents), put a hole reducer on it.
The Doppler effect widens the spectral lines of rotating objects because the wavelengths changes from blue or red. Blue-shifted, red-shifted, and non-shifted photons mix together to get how its rotating.
Itâs often compared to the way a police officer catches you when youâre speeding. But, in the case of astronomy, these answers all come from our ability to detect miniscule changes in the color of light. Police and astronomers both rely on a principle called the Doppler shift.