Explanation:
An unusual triangle of light is visible this time of year just before dawn, in the northern hemisphere.
Once considered a false dawn, this triangle of light is actually
Zodiacal Light, light reflected from
interplanetary dust particles.
The bright reflecting triangle is clearly visible on the right of the above image
taken from Laguna Verde near
Valparaíso,
Chile in late July.
The
band of our
Milky Way Galaxy on the left mirrors the zodiacal band.
Zodiacal dust
orbits the Sun
predominantly in the same plane as the planets: the
ecliptic.
Zodiacal light is so bright in the north this time of year because the
dust band is oriented
nearly vertical at sunrise,
so that the thick air near the horizon does not block
out relatively bright reflecting dust.
Zodiacal light is also bright for
people
in Earth's northern hemisphere in March and April just after sunset.
In the southern hemisphere,
zodiacal light is most notable after sunset in late summer, and brightest before sunrise in late spring.
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