Meteor shower

These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extremely high speeds on parallel trajectories.

[11] He noted the shower was of short duration and was not seen in Europe, and that the meteors radiated from a point in the constellation of Leo.

[12] Work continued, yet coming to understand the annual nature of showers though the occurrences of storms perplexed researchers.

Meteors were conceived as an atmospheric phenomenon by many scientists (Alexander von Humboldt, Adolphe Quetelet, Julius Schmidt) until the Italian astronomer Giovanni Schiaparelli ascertained the relation between meteors and comets in his work "Notes upon the astronomical theory of the falling stars" (1867).

Although the absence of meteor storms that season confirmed the calculations, the advance of much better computing tools was needed to arrive at reliable predictions.

In 1985, E. D. Kondrat'eva and E. A. Reznikov of Kazan State University first correctly identified the years when dust was released which was responsible for several past Leonid meteor storms.

[17] In anticipation of the 1999 Leonid storm, Robert H. McNaught,[18] David Asher,[19] and Finland's Esko Lyytinen were the first to apply this method in the West.

[23] Because meteor shower particles are all traveling in parallel paths and at the same velocity, they will appear to an observer below to radiate away from a single point in the sky.

A meteor shower results from an interaction between a planet, such as Earth, and streams of debris from a comet (or occasionally an asteroid).

Comets can produce debris by water vapor drag, as demonstrated by Fred Whipple in 1951,[24] and by breakup.

Whipple envisioned comets as "dirty snowballs", made up of rock embedded in ice, orbiting the Sun.

Each time a comet swings by the Sun in its orbit, some of its ice vaporizes, and a certain number of meteoroids will be shed.

The fragments tend to fall apart quickly into dust, sand, and pebbles and spread out along the comet's orbit to form a dense meteoroid stream, which subsequently evolves into Earth's path.

The gravitational pull of the planets determines where the dust trail would pass by Earth orbit, much like a gardener directing a hose to water a distant plant.

This effect was first demonstrated from observations of the 1995 alpha Monocerotids,[25][26] and from earlier not widely known identifications of past Earth storms.

When the meteoroids pass by Earth, some are accelerated (making wider orbits around the Sun), others are decelerated (making shorter orbits), resulting in gaps in the dust trail in the next return (like opening a curtain, with grains piling up at the beginning and end of the gap).

Also, Jupiter's perturbation can dramatically change sections of the dust trail, especially for a short period comets, when the grains approach the giant planet at their furthest point along the orbit around the Sun, moving most slowly.

As the Moon is in the neighborhood of Earth it can experience the same showers, but will have its own phenomena due to its lack of an atmosphere per se, such as vastly increasing its sodium tail.

The Martian atmosphere has less than one percent of the density of Earth's at ground level, at their upper edges, where meteoroids strike; the two are more similar.

Only the relatively slower motion of the meteoroids due to increased distance from the sun should marginally decrease meteor brightness.