The Zodiacal Dust Cloud
The Zodiacal Light, Band and Gegenschein are caused by sunlight reflecting off tiny interplanetary dust particles (IDPs), which, like the planets, lie in the plane of the Solar System. These sky glows are one and the same phenomenon: they only look different in shape and brightness because of the angle of the light reflected from the particles in the interplanetary dust cloud.
Your best chance to catch a glimpse of these phenomena is in spring and autumn when the Ecliptic makes a steep angle to the horizon (see image). Look towards the west after sunset and after twilight has completely subsided, or towards the east before dawn. The closer you live to the Tropics, the better your chances of seeing the glows.
Most of the IDPs are between 10 and 300 micrometers across (4/10,000 to 1/100 of an inch) and are composed mainly of silicates, similar to much of the material found in the Earth’s crust. They are largely confined to the inner Solar System, stretching out to the orbit of Jupiter at 5.2 AU (779 million kilometers from the Sun.)
The IDPs themselves are as old as the Solar System, around 4.56 billion years, but they exist as discrete dust particles for probably less than 100 million years. This is because of the complex dynamics to which the IDPs are subject.
Like everything else in the Solar System, IDPs orbit the Sun. Where they differ from other larger objects, however, is that they tend to spiral inwards, their orbits gradually decreasing in size as time progresses. What causes this is the way the IDPs react with light and other forms of solar radiation. The dust particles absorb light and then re-radiate some of it at a different wavelength. This causes a tangential drag on the dust particle: it loses orbital energy and so begins to spiral down towards the Sun, a phenomenon known as the Poynting-Robertson Effect. All objects in the Solar System process radiation in the same way. However, for larger bodies the tangential drag is negligible, so there is no fear of the Earth drifting towards the Sun.
If this was the only process at work, then all IDPs would eventually get so close to the Sun that they would vaporize, and, indeed, many do. But a significant number escaped this fate. Space weathering involving inter-particle collisions, thermal shock and the evaporation of some minerals can reduce the mass of a particle to such an extent that the pressure of solar radiation overcomes the tangential drag and stops the particle in its tracks, lodging it into a near-circular orbit. Though not for long.
An increase in radiation pressure and further space weathering may reduce the mass of the particle further and push it back out towards Jupiter. On its way the dust particle may encounter other IDPs and either break up further or stick to them. So the life cycle of a single IDP can be complex but, whatever the scenario, it is unlikely that an IDP could remain in the Solar System for more than about 100 million years. Apart from the possibilities noted above, some IDPs will fall into the planets, producing the sporadic meteors we have already mentioned, while others will be gravitationally kicked out of the Solar System by massive Jupiter.