What is the Zodiacal Light?
Way way way back in the days when our knowledge of astronomy was considerably less than today’s, many people used to think this light was caused by some unknown phenomena that occurred within the Earth’s atmosphere, it is also known as a False Dawn. But we soon came to find out that this wasn’t the case at all, in fact, the lighting is really caused by the reflection of little dust particles moving in outer space. Pretty awesome right?
Scientists think that some of these dust particles are possibly grains left over from the very process that formed our solar system 4.5 billion years ago.
Images: Zodiacal Light and Milky Way over Paranal, Zodiacal Light and Milky Way, Zodiacal Light from Veronica
These dust grains in space spread out from the sun in the same flat disc of space inhabited by Mercury, Venus, Earth, Mars and the other planets in our sun’s family. This flat space around the sun – the plane of our solar system – translates on our sky to a narrow pathway called the ecliptic. This is the same pathway traveled by the sun and moon as they journey across our sky.
The pathway of the sun and moon was called the Zodiac or Pathway of Animals by our ancestors in honor of the constellations seen beyond it. The word zodiacal stems from the word Zodiac.
In other words, the zodiacal light is a solar system phenomenon. The grains of dust that create it are like tiny worlds – ranging from meter-sized to micron-sized – densest around the immediate vicinity of the sun and extending outward beyond the orbit of Mars. Sunlight shines on these grains of dust to create the light we see. Since they lie in the flat sheet of space around the sun, we could – in theory – see them as a band of dust across our entire sky, marking the same path that the sun follows during the day. And indeed there are sky phenomena associated with this band of dust, such as the gegenschein. But seeing such elusive sky phenomena as the gegenschein is difficult. Most of us see only the more obvious part of this dust band – the zodiacal light – in either spring or fall.
Under what sky conditions might you see it? You’ll need a dark sky location to see this false dawn, or zodiacal light, someplace where city lights aren’t obscuring the natural lights in the sky. The zodiacal light is even milkier in appearance than the summer Milky Way, but if you can see the Milky Way you can also see the zodiacal light. [EarthSky]
More cool pics of the Zodiacal Light here