No one need worry too much about a repeat with that well known comet a piece of pulled in by earth gravity which hit over Tunguska. There is a significant chance the next time it passes around the sun the gravity of the sun in one swallow will pull it in and it will perish. Many comets perish this way. In London the black early morning following it losing a piece of itself to earth gravity was no longer black. In London, England golfers were out on the course improving the skills of their game at 2 A.M. in the morning and enjoying the marvel. There but for the grace of God go you and I. Tunguska was not a punishment by God for sin or about sin. It was a natural event. It could be about sin or a punishment by God for sin if it is not comprehended. A precursor.  (Comets orbit around the sun and then head to and pass by earth with the sun's solar wind pushing the materials stream of the comet out in front of the more dense central core of the comet. As it goes around the sun the sun with its gravity can pull pull the entire comet in and the comet is destroyed, or the sun can break off a part of the comet stream and pull it closer to itself on a new path but not into itself as the comet continues its pass around the sun. And the gravitation of the sun can slow comets down some. In its pass around the sun and towards earth the comet now in effect is scattered and deflected parts of the comet passing nearer to earths gravitation may be pulled in by earth because of the now increased nearness or slow down.  The comet itself or parts of it is now more succeptable to the gravitational pull of the earth, and other planets it passes.                                                                              Most comet material is eventually pulled into the sun by gravitation and perishes. Some comet material (or all in limited cases) through this process of scattering, path deflection and slow down by the sun in terms of the comet path is pulled into the earth and other planets by gravity. In terms of "universe time" comets in our solar system have a short life span because of sun and planet gravity which eventually makes comet materials a part of themselves. In the case of Tunguska the earth made the passing comet materials a part of earth. Jupiter with comet Schumacher Levy made the comet a part of Jupiter. These are examples.                                                                       Incidentally it is believed (hypothesis) that it was approximately 1,500 years ago that pieces of Enckes comet broke off being captured in the gravity of the earth somewhat like the moon - with exception that there was an eliptical orbit around earth and sun - with some of the small solid mineral particles in the core losing early their vapor and ice to the gravity of the sun, planets and asteroids. The broken off piece of Enckes comet that hit Tunguska very late in June 1908 at the peak of Enckes Beta Taurids meteors and the shower they create had stayed intact and there may be many other intact pieces of Enckes comet in eliptical orbit around the earth and sun yearly. Enckes comet itself visits the earth like clockwork every between 3 and 4 years. It visits the earth more frequently than any comet yet recorded. It is not a big comet. The piece of Enckes comet that hit Tunguska had become a very very small comet in itself, circling the earth once a year along with the Enckes comet Beta Taurids meteors and had gone unnoticed by heavens watchers being a very very small comet. Matter it bumped into in space over 1,500 years had slowed it down to a point where it could not escape the earths gravity pull into terra firma. Although a very very small comet it hit the Tunguska area with the energy of twenty (20) one megaton nuclear warheads.                                                                                      There is near perfect alignment but not perfect alignment between the Enckes comet piece Tunguska comet, the Enckes comet Beta Taurids meteors and Enckes Comet itself which visits the earth so frequently every few years. This is attributed to differential in the gravitational pull of the planet Jupiter as the Enckes comet rounds the sun at relatively high speed to be flung in a reverse direction past the earth and out into space untill solar space matter slows it down and it falls back towards the sun. Enckes comet is a tame comet. Some comets at their closest to the sun coming in on their path having reached the speed of 1,250,000 miles and hour (one million two hundred and fifty thousand miles an hour) and are reversely flung out by the sun to beyond the planet Pluto to where they slow down to ten miles an hour and shortly thereafter begin falling back towards the sun. This phenomena happens over and over again on the solar time calendar. These unusual comets do not visit the earth frequently. There by the grace of God go you and I.