What is zodiacal dust?
1 Answer
Zodiacal dust is cosmic dust.
Explanation:
Zodiacal dust is most commonly known for Zodiacal light which is
"a faint, roughly triangular, diffuse white glow seen in the night sky that appears to extend up from the vicinity of the Sun along the ecliptic or zodiac. It is caused by sunlight scattered by space dust in the zodiacal cloud. It is best seen just after sunset in spring, and just before sunrise in autumn, when the zodiac is at a steep angle to the horizon but is so faint that either moonlight or light pollution renders it invisible." [1]
Zodiacal light in the eastern sky before the beginning of morning twilight.
Zodiacal dust is simply cosmic dust located mainly between the Sun and Jupiter. This dust is "10 and 300 micrometres in diameter, most with a mass around 150 micrograms." [1] The light effect is caused due in part to the large collection of this dust in the aforementioned area and also in part to the Sun's reflection off of this dust.
Tiny cosmic dust
As far as why observing Zodiacal dust is so rare can be attributed to forward scattering. This type of light deflection makes the dust only " just after sunset in spring, and just before sunrise in autumn when the zodiac is at a steep angle to the horizon but is so faint that either moonlight or light pollution renders it invisible." [1]
Further Reading:
Zodiacal Light:
https://en.wikipedia.org/wiki/Zodiacal_light
http://coolcosmos.ipac.caltech.edu/cosmic_classroom/cosmic_reference/zodydust.html
Cosmic Dust:
https://en.wikipedia.org/wiki/Cosmic_dust
