But with heights, it is a different story. For distributions of quantities like heights, it is necessary to consider ranges . Ranges are often called bins , which comes from the notion of sorting objects of different sizes, and putting them in appropriate bins. Let us see how this works for light photons. Astronomers must know quite a lot about the properties of light photons that come from stars or planets.
Photons are bundles of oscillating electric and magnetic fields.
If this frequency is given by the Greek letter , then the energy of the photon is , where h is a universal constant, known as Planck's constant. The frequencies associated with photons can take any value, and are not limited to discrete numbers. In addition to frequency, light photons have wavelengths, usually designated . The product of the frequency and wavelength gives the velocity. In many cases of interest in astronomy, the light travels through a near vacuum at a velocity very close to c .