Rayleigh

Rayleigh may refer to:

Science

Title of nobility

Rayleigh (unit)

The rayleigh is a unit of photon flux, used to measure airglow (auroras, for example). It was first proposed in 1956 by D. M. Hunten, Franklin E. Roach, and J. W. Chamberlain. It is named for Robert John Strutt, 4th Baron Rayleigh (1875–1947). Its symbol is R (also used for the röntgen, an unrelated unit). SI prefixes are used with the rayleigh.

One rayleigh (1 R) is defined as a column emission rate of 10¹⁰ photons per square metre per column per second. Note that rayleigh is an apparent emission rate, as no allowances have been made for scattering or absorption. The night sky has an intensity of about 250 R, while auroras can reach values of 1000 kR.

The relationship between photon radiance, L, (in units of photons per square metre per second per steradian) and I (in units of rayleighs) is

References

Rayleigh (lunar crater)

Rayleigh is a lunar crater that lies along the northeast limb of the Moon. This feature is seen edge-on from Earth, making it difficult to see much detail. In addition, libration effects can completely hide this crater from view. It lies just to the north of Lyapunov, and to the northwest of the large Joliot. Attached to its southwest rim is the smaller Urey.

This is an eroded formation with a rim that has been worn and reshaped by impacts. This is particularly so in the south where the rim has been modified and supplemented by adjacent crater formations and several small craters that lie along the rim.

The interior floor is relatively level in places, but, partly due to overlapping ejecta, is somewhat rough and irregular in others, particularly in the southern half. A pair of small but prominent craters lies on the interior surface, with Rayleigh D just to the south of the crater midpoint and the smaller Rayleigh B situated in the western half.

Rayleigh was named for John William Strutt, 3rd Baron Rayleigh.