Shoemaker-Levy 9 is more akin to a handful of marbles than a baseball.
Each time a periodic comet
revisits the inner solar system, it can experience the gentle effects of dust-bearing gas jets erupting on its sun-warmed surface.
It originated from Swift-Tuttle, a periodic comet
that completes its orbital cycle every 133 years.
A preceding P means you're looking at a periodic comet
(any comet with an orbital period of 200 years or less).
The Perseids are pieces of Periodic Comet
Matese at the University of Southwestern Louisiana in Lafayette created the new theory by merging two ideas that were proposed in the past for reasons totally unrelated to periodic comet
impacts and mass extinctions: a tenth planet, dubbed Planet X and envisioned to reside beyond the orbit of Pluto; and a disk or belt of comets throught to lie in the plane of the solar system beyond Neptune.
The meteors are actually fragments coming off of the Giacobini-Zinner periodic comet
that passes Earth every six years and four months.
Rosetta launched in March 2004, and after a long cruise that included flybys of Earth, Mars, and two asteroids--plus an unnervingly long hibernation period--the spacecraft arrived at its primary target, a periodic comet
called 67P/Churyumov-Gerasimenko, in August 2014.
These periodic comet
showers appear to correlate with the dates of ancient impact craters found on Earth, which would suggest that most impactors in the past were comets, not asteroids.
41P/Tuttle-Giacobini-Kresak may be reaching 6th or even 5th magnitude very high in the northern evening sky.
It was first viewed in 1948, making it the 45th discovered periodic comet
after Haley's comet, the (http://nypost.com/2017/02/08/get-ready-for-a-rare-celestial-trifecta/) New York Post reported.
According to Nasa, this meteor storm would result "from the dust of periodic comet
209P/LINEAR, a Jupiter family comet discovered by the Lincoln Laboratory Near-Earth Asteroid Research project in 2004".