Seeing a meteor is always an exciting experience, partly because each one is different. Faint “shooting stars” seldom have an identifiable shade – but seeing a deeply colored flash adds something extra to the good fortune of seeing a meteor that can compete with the brightest stars.
If you are lucky enough to experience a meteor shower (or better still, a storm) the contrasting colors can take things to an extra level. Meanwhile, for researchers, the color can indicate the chemistry of the dust that made the event, which can be significant when we know its origins.
Meteors are caused by dust particles, and sometimes something larger, burning up in the Earth’s atmosphere. The extreme speeds with which they hit create a lot of friction, which heats the incoming object to the point where it releases light that seems out of all proportion to the tiny amount of material involved.
If you toss a chemical sample in a fire (please use proper safety precautions, and don’t blame us for the consequences if you don’t) the burst of light will have a distinctive color. This is the basis of the flame test, invented by Robert Bunsen, of Bunsen burner fame. Electrons supplied with enough energy jump to a higher state. When they drop back, they release light at a wavelength specific to that element, which we see as a specific color.
Detection of that wavelength can reveal an element’s presence in any sufficiently hot environment, be it a laboratory flame, a star, or a meteor.
The same process allows us to make fireworks in many colors. The particles that produce meteors are seldom pure, but if one element dominates, it can produce a distinct shade.
Meteorites are just meteors that were large enough to make it to the ground without burning up entirely. The most common elements in meteorites are silicon, oxygen, and iron.
Their smaller counterparts have similar composition, with the iron giving many a yellow glow. Sodium, which produces an orange-yellow glow that can be hard to distinguish from iron unless it is bright or long, also sometimes contributes.
The colors don’t always match those commonly reported from flame tests, however. For example, calcium in a Bunsen burner gives an orange-red light. However, according to NASA, the presence of calcium in a meteor is signaled by a violet tinge. The difference is because the calcium in meteors is ionized Ca+. Similarly, magnesium in a meteor creates a blue-green shade, different from the white seen when magnesium metal burns. In a lab, iron can produce a gold color when it is Fe2+ or be orange-brown when Fe3+. The orange-yellow association with iron indicates which is more common in space.
Read more: https://www.iflscience.com/what-do-meteors-colors-tell-us-71928
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