Chuck Bednar for redOrbit.com – @BednarChuck
Stargazers in the northern hemisphere this month will have the opportunity to catch a glimpse of an unusual phenomenon known as the zodiacal light or the Pyramid of Light.
Reflecting dust
According to National Geographic, the zodiacal light (also known as false dawn) is best viewed by looking toward the western horizon approximately one hour after sunset. When looking at them from a dark countryside, the lights (which get their name from the band of constellations that the sun, moon, and planets pass through) are similar in appearance those of a far off city, except that they are more ghostly or ethereal in nature.
So exactly what is zodiacal light? Nat Geo explains that it is caused by sunlight reflecting off billions of dustlike particles found in the inner solar system. These particles are said to be bits that were left over after the Earth and the other planets formed over 4 1/2 billion years ago.
[STORY: Dust in early universe proves galaxies were quickly enriched]
Similarly, the Internet Encyclopedia of Space refers to the zodiacal light as “a faint glow of light scattered off the zodiacal dust,” adding that the phenomenon “can sometimes be seen under very dark sky conditions, along the horizon, either just after dusk or before sunrise.”
But wait…there’s more!
Zodiacal dust, the website added, is a group of particles between one and 300 microns in diameter. In addition to being remnants of planet formation, the dust can also come from the tails of comets and from collisions between asteroids. Together, the particles have come together to form a flat disk know as the zodiacal cloud.
[STORY: Exozodiacal light detected around nine stars]
False dawn can be viewed both in the spring and the fall. When it is visible in the spring, it tends to be most visible shortly after sunset (as is the case this month). When it takes place in the autumn, such as the one reported on by the folks at Space.com last September, the faint, white, triangular glow is best seen just before sunrise.
How to view
In order to get your best look at the phenomenon, EarthSky recommends that you travel to an area where city lights are not obscuring the sky’s natural lights – the darker your surroundings, the better. An evening with no moon in the sky will be your best bet.
“The zodiacal light is easiest to see when true night falls in spring, because then the ecliptic is most perpendicular to the western horizon in the evening,” the website explained, adding that the Pyramid of Light “can be seen for up to an hour after all traces of evening twilight leave the sky. Unlike true dawn or dusk, though, there’s no rosy color to the zodiacal light.”
[STORY: NASA finds planet with four suns]
The reason for this, according to experts, is because the reddish hues visible at true dawn and dusk are caused by the Earth’s own atmosphere. While scientists did believe at one point that the lights of the false dawn somehow originated in the upper atmosphere of the Earth, they have since learned that they come from well beyond our planet’s atmosphere.
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