Phase Angle
The phase angle is the Sun-Target-Observer angle. A phase angle of zero indicates that the Sun is, in effect, shining over your shoulder so you see a fully-lit target (like a full Moon).
Phase Angle
The angle measured at the center of an illuminated body between the light source and the observer.
Reference: ...
Phase angle. For a solar system object besides the earth and sun, the angle between the earth and the sun (or the earth's elongation from the sun) as seen from that third object.
Phase angle (disambiguation)Phase cancellationPhase center
Phase change heat pumpPhase Change MaterialPhase constant
Phase contrast microscopePhase converterPhase cutting ...
The phase angle or terminator will increase from the time we first see Mars rising early in the morning sky until a week or two before western quadrature. After quadrature the phase will decrease until it nearly disappears around opposition.
(b) Angle subtended (8".79) by the equatorial radius of the Earth at a distance of 1 AU. [H76]
Solar Phase Angle ()
Angular distance at the planet between the Earth and the Sun. [H76]
Solar Prominence ...
is 1 au, is the phase angle, the angle between the Sun-Body and Body-Observer lines; by the law of cosines, we have:
is the phase integral (integration of reflected light; a number in the 0 to 1 range) ...
Taken from a high phase angle of 148 degrees - a viewing geometry in which small particles become much easier to see - the plume of material becomes more apparent in images processed to enhance faint signals.
phase angle 1. The phase difference of two periodically recurring phenomena of the same frequency, expressed in angular measure. 2. The angle at a celestial body between the sun and earth. phase constant See propagation constant.
North of 55° in Europe its phase angle seems fairly constant, not differing very much from the value 110° in Lovering's general formula. The 6-month term is small, in the two most northern stations, but south of 60° N. lat.
This was global mapping phase 1, the phase angle during this phase was small, no greater than 20°-25°.
Scattering of sunlight at large phase angles, when the rings are almost between the Sun and the Voyager camera, also reveals small dust particles, whose size is comparable to the wavelength of light.
A low phase angle provides high sun illumination, similar to taking a picture from a high altitude at noon (with the sun directly overhead). Such illumination emphasizes the brightness contrasts of light and dark areas.
On Earth, we never see a perfectly full Moon, since the true phase angle we see is in the order of 5 degrees. With a zero degree phase angle the Moon would be in Earth's shadow, and we would experience a total lunar eclipse.
Because the orbit of Jupiter is outside the Earth's, the phase angle of Jupiter as viewed from the Earth never exceeds 11.5°, and is almost always close to zero.
The magnitude of an asteroid at zero phase angle and at unit heliocentric and geocentric distances.
Reference:
Asteroids II. 1989. R.P. Binzel, T. Gehrels, and M.S. Matthews, Eds., University of Arizona Press, Tucson.
Note that the figure of the phase angles above shows just one of the angles possible for the crescent phase (at 45°).
imaging science subsystem solid state imager ssi near infrared imaging spectrometer nims new horizons lorri long range reconnaissance imager hubble space telescope hst wide field planetary camera 2 wfpc2 wfpc general advanced geometry phase angle ...
 See also: Phase, Earth, Sun, Distance, Solar
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