The Leonids is a prolific meteor shower that the Earth encounters in November during its annual trip around the Sun.
The Leonids appear to radiate from the constellation Leo in the night sky.
The constellation Leo appears close to the horizon with a declination of +15 degrees.
The source of the Leonids meteor shower is associated with Comet Tempel–Tuttle
55P/Tempel–Tuttle (commonly known as Comet Tempel–Tuttle) is a periodic comet with an orbital period of 33 years.
It fits the classical definition of a Halley-type comet with (20 years < period < 200 years).
It was independently discovered by Ernst Tempel on December 19, 1865 and by Horace Parnell Tuttle on January 6, 1866.
It is the parent body of the Leonid meteor shower.
The orbit of 55P/Tempel–Tuttle intersects that of Earth near exactly, hence streams of material ejected from the comet during perihelion passes do not have to spread out over time to encounter Earth.
This coincidence means that streams from the comet at perihelion are still dense when they encounter Earth, resulting in the 33 year cycle of Leonid meteor storms.
For example, in November 2009, the earth passed through meteors left behind mainly from the 1466 and 1533 orbit.
The Leonid meteors are fast [72 km/s] and are know to be furious [exceeding 1,000 per hour].
The Leonids are a fast moving stream which encounter the path of Earth and impact at 72 km/s.
Larger Leonids which are about 10 mm across have a mass of half a gram and are known for generating bright (apparent magnitude -1.5) meteors.
An annual Leonid shower may deposit 12 or 13 tons of particles across the entire planet.
The meteoroids left by the comet are organized in trails in orbits similar to though different from that of the comet.
They are differentially disturbed by the planets, in particular Jupiter and to a lesser extent by radiation pressure from the sun, the Poynting–Robertson effect, and the Yarkovsky effect.
These trails of meteoroids cause meteor showers when Earth encounters them.
Old trails are spatially not dense and compose the meteor shower with a few meteors per minute.
In the case of the Leonids, that tends to peak around November 18, but some are spread through several days on either side and the specific peak changes every year.
Conversely, young trails are spatially very dense and the cause of meteor outbursts when the Earth enters one.
Meteor storms (large outbursts) exceed 1000 meteors per hour, to be compared to the sporadic background (5 to 8 meteors per hour) and the shower background (several per hour).
Fast moving meteors, like the Leonid, can create fireballs in the night sky as they burn up in the Earth’s atmosphere.
The NASA All Sky Fireball Network scans the skies above the United States for fireballs and calculates their orbits and velocity [amongst other things].
All Sky Fireball Network
Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA’s Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth’s atmosphere and many other characteristics. Daily results are presented here on Spaceweather.com.
Viewing the published fireball orbits for the last few weeks provides a fascinating insight into the Leonids.
The Leonids were anticipated between the 15th and 20th of November 2013 with a predicted peak occurring on the 17th November 2013.
Unfortunately, Spaceweather.com did not publish the fireball orbital data for the 18th November.
However, a peak of fireball activity can be observed during the 19th, 20th and 21st of November.
The first big surprise is that the “Leonid” peak in fireballs was primarily caused by “Sporadics”.
The Leonids are outnumbered 2:1 by meteors with orbits that are not aligned with Comet Tempel–Tuttle.
The second big surprise is that so many fireballs have intersected with Earth’s orbit.
This is a remarkably tight cluster of sporadic meteors with varying orbital trajectories that all just happen to converge upon the Earth during this three day period.
The third big surprise is the trajectories of the meteors show a clear impact pattern.
Triage from an Earth impact event appears to have been blasted into a diverse array of orbits around the Sun after the Earth collided with an inbound [towards the Sun] object originating in the top right quadrant of the diagrams.
The orbital diagram for the 21st November clearly depicts [in green] a single meteor with an orbit that is orientated towards this top right quadrant.
The presence of this lingering meteor [in green] suggests that the impact event was associated with a number of inbound objects originating from a common source [some of which are still in orbit around the sun].
The coincidental intersection of the Earth’s orbit with Comet Tempel–Tuttle and this prolific number of sporadic meteors [over such a short space of time] statistically suggests that the primary object impacting the Earth was Comet Tempel–Tuttle and the associated sporadic meteors are triage from this event.
It is not beyond the bounds of possibility that the initiating event [that blasted debris towards Earth] was The “Other” Big Bang event that created the comet family of Jupiter and the asteroid belt between Mars and Jupiter.
The Other Big Bang Theory