Opposition surge from the retroreflective lunar soil brightens the area around Buzz Aldrin's shadow during Apollo 11 (photo by Neil Armstrong).
The opposition surge (sometimes known as the opposition effect, opposition spike or Seeliger effect[1]) is the brightening of a rough surface, or an object with many particles, when illuminated from directly behind the observer. The term is most widely used in astronomy, where generally it refers to the sudden noticeable increase in the brightness of a celestial body such as a planet, moon, or comet as its phase angle of observation approaches zero. It is so named because the reflected light from the Moon and Mars appear significantly brighter than predicted by simple Lambertian reflectance when at astronomical opposition. Two physical mechanisms have been proposed for this observational phenomenon: shadow hiding and coherent backscatter.
^Hameen-Anttila, K.A.; Pyykko, S. (July 1972). "Photometric behaviour of Saturn's rings as a function of the saturnocentric latitudes of the Earth and the Sun". Astronomy and Astrophysics. 19 (2): 235–247. Bibcode:1972A&A....19..235H.
The oppositionsurge (sometimes known as the opposition effect, opposition spike or Seeliger effect) is the brightening of a rough surface, or an object...
)=\cos {\alpha }} , which isn't realistic, but it does represent the oppositionsurge for rough surfaces that reflect more uniform light back at low phase...
The Iraq War troop surge of 2007, commonly known as the troop surge, or simply the surge, refers to the George W. Bush administration's 2007 increase...
because the bright sunlight reflected by the Moon, amplified by the oppositionsurge, then outshines many stars. There are eight phases of the moon, which...
shadow Heiligenschein Interplanetary dust cloud Kordylewski cloud Oppositionsurge, the apparent brightening of a coarse surface or an aggregate of many...
Any retroreflective surface is brightest around the antisolar point. Oppositionsurge by other particles than water and the glory in water vapour are similar...
which creates a bright spot around the shadow of the viewer's head Oppositionsurge, the brightening of a rough surface, or an object with many particles...
Varuna's light curve near opposition, indicating variations of scattering properties over its surface. The oppositionsurge of Varuna differs from those...
— The width of the oppositionsurge. B 0 {\displaystyle B_{0}} or S 0 {\displaystyle S_{0}} — The strength of the oppositionsurge. P 0 {\displaystyle...
parhelic circle itself. Astronomy portal Space portal Heiligenschein Oppositionsurge Subparhelic circle Sylvanshine Herd, Tim (2007). "Angular Measurements...
albedo is even lower—about 2%. The rings particles demonstrate a steep oppositionsurge—an increase of the albedo when the phase angle is close to zero. This...
for a distant object. As Huya comes to opposition, its brightness increases as a result of an oppositionsurge, in which its phase angle approaches zero...
towards the Sun at the unlit backside of the object. In addition, oppositionsurge makes asteroids even brighter when the Earth is close to the axis of...
popularity of Narendra Modi, effective voter turnout drives by the NDA, a surge in public nationalism following the Pulwama attack, the consolidation of...
after the Sun. This is due partly to the brightness enhancement of the oppositionsurge; the Moon at quarter phase is only one-tenth as bright, rather than...
who disagree with the outcome of these "elections". The current surge of mass opposition rallies has been called in some publications "a snow revolution"...
The characteristic impedance or surge impedance (usually written Z0) of a uniform transmission line is the ratio of the amplitudes of voltage and current...
Kagan supported "the Surge" strategy in Iraq and argued for a restructured American military strategy more generally. The Surge: The Untold Story, co-produced...
scattering alignment (FSA), a coordinate system primarily used in optics Oppositionsurge, an astronomical phenomenon caused by the coherent backscatter effect...
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