posted on May, 19 2012 @ 04:18 PM
Originally posted by Trueman
Originally posted by Ph03n1x
interesting..i shall have to keep an eye on this...nice find..
it could be a meteor i guess but they don't usually have ''blue/green'' lights do they? i am no expert
I think the color depends of what is it made of.
The composition of the object can influence the colour, but so can the velocity, and in many cases the colour is heavily influenced by the gaseous
composition of the atmosphere, which varies with altitude.
Another major factor influencing what colours are reported in a meteor, is human visual perception. It's not unusual for two people observing next to
each other, to report the same meteor as having different colours. So not much importance is attached to the reported colors of meteors.
For more consistent/meaningful observations of colour, researchers will usually resort to photography, which usually involves using a diffraction
grating to obtain meteor spectra. From a meteor spectrum it's possible to tell which elements are present.
Can fireballs appear in different colors?
Vivid colors are more often reported by fireball observers because the brightness is great enough to fall well within the range of human color vision.
These must be treated with some caution, however, because of well-known effects associated with the persistence of vision. Reported colors range
across the spectrum, from red to bright blue, and (rarely) violet. The dominant composition of a meteoroid can play an important part in the observed
colors of a fireball, with certain elements displaying signature colors when vaporized. For example, sodium produces a bright yellow color, nickel
shows as green, and magnesium as blue-white. The velocity of the meteor also plays an important role, since a higher level of kinetic energy will
intensify certain colors compared to others. Among fainter objects, it seems to be reported that slow meteors are red or orange, while fast meteors
frequently have a blue color, but for fireballs the situation seems more complex than that, but perhaps only because of the curiosities of color
vision as mentioned above.
The difficulties of specifying meteor color arise because meteor light is dominated by an emission, rather than a continuous, spectrum. The
majority of light from a fireball radiates from a compact cloud of material immediately surrounding the meteoroid or closely trailing it. 95% of this
cloud consists of atoms from the surrounding atmosphere; the balance consists of atoms of vaporized elements from the meteoroid itself. These
excited particles will emit light at wavelengths characteristic for each element. The most common emission lines observed in the visual portion of the
spectrum from ablated material in the fireball head originate from iron (Fe), magnesium (Mg), and sodium (Na). Silicon (Si) may be under-represented
due to incomplete dissociation of SiO2 molecules. Manganese (Mn), Chromium (Cr), Copper (Cu) have been observed in fireball spectra, along with rarer
elements. The refractory elements Aluminum (Al), Calcium (Ca), and Titanium (Ti) tend to be incompletely vaporized and thus also under-represented in
Source: The American Meteor Society Fireball FAQs