Zodiacal Light and the False Dawn
An unusual triangle of light will be particularly
bright near the eastern horizon before sunrise
during the next two months for observers in Earth's northern
hemisphere.
Once considered a false dawn, this triangle of light is actually
Zodiacal Light, light reflected from
interplanetary dust particles.
The triangle is clearly visible on the left of the
above frame taken from
Mauna Kea in
Hawaii on September 8 by one of the developing global network of fisheye nighttime web cameras,
called CONCAMs, of the
Night Sky Live Project.
Zodiacal dust
orbits the
Sun
predominantly in the same plane as the planets: the
ecliptic.
Zodiacal light is so bright 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.