Saturn eclipses the Sun, as seen from the Cassini space probe. The forward scattering of light makes the faint outer rings more visible.

Forward scatter is the deflection of waves in general (or more specifically, electromagnetic waves) in a way that they headed against direction from which they came. This might be caused by diffraction, nonhomogeneous refraction, or nonspecular reflection by particulate matter that are large with respect to the wavelength in question but small with respect to the beam diameter. The forward scattering process may be sensitive to polarization of the wave. Forward scatter is essentially the reverse of backscatter.

Comets

Forward scattering can make a back-lit comet appear significantly brighter because the dust and ice crystals are reflecting and enhancing the apparent brightness of the comet by scattering that light towards the observer.[1] Comets studied forward-scattering in visible-thermal photometry include C/1927 X1 (Skjellerup–Maristany), C/1975 V1 (West), and C/1980 Y1 (Bradfield).[2] Comets studied forward-scattering in SOHO non-thermal C3 coronograph photometry include 96P/Machholz and C/2004 F4 (Bradfield).[2] The brightness of the great comets C/2006 P1 (McNaught) and Comet Skjellerup–Maristany near perihelion were enhanced by forward scattering.[3]

References

  1. ↑ "Comet Elenin as seen by STEREO-B, and what we think is going to happen next..." Sungrazing Comets. Retrieved 2011-08-05.
  2. 1 2 Marcus, Joseph C. (2007). "Forward-Scattering Enhancement of Comet Brightness. I. Background and Model". International Comet Quarterly. 29 (2): 39–66. Bibcode:2007ICQ....29...39M.
  3. ↑ Marcus, Joseph N. (October 2007). "Forward-Scattering Enhancement of Comet Brightness. II. The Light Curve of C/2006 P1" (PDF). International Comet Quarterly. 29: 119–130. Bibcode:2007ICQ....29..119M. Archived from the original (PDF) on 2011-07-08.

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