At this time a number of researchers, most notably Eugene M. Shoemaker, ( co-discoverer of the comet Shoemaker-Levy 9 ), conducted detailed studies of a number of craters and recognized clear evidence that they had been created by impacts, specifically identifying the shock-metamorphic effects uniquely associated with impact events, of which the most familiar is shocked quartz.

It was the first comet observed to be orbiting a planet, and had probably been captured by the planet around 20 – 30 years earlier.

At that time, the orbit of Shoemaker – Levy 9 passed within Jupiter's Roche limit, and Jupiter's tidal forces had acted to pull the comet apart.

Because of this, he suggested that the Shoemakers and David Levy had discovered the fragments of a comet that had been disrupted by Jupiter's gravity.

Although the comet had approached Jupiter closely before, the July 7 encounter seemed to be by far the closest, and the fragmentation of the comet is thought to have occurred at this time.

The discovery that the comet was likely to collide with Jupiter caused great excitement within the astronomical community and beyond, as astronomers had never before seen two significant Solar System bodies collide.

Astronomers estimated that the visible fragments of SL9 ranged in size from a few hundred metres to two kilometres across, suggesting that the original comet may have had a nucleus up to acrosssomewhat larger than Comet Hyakutake, which became very bright when it passed close to the Earth in 1996.

Before the impact, models of Jupiter's atmosphere had indicated that the break-up of the largest fragments would occur at atmospheric pressures of anywhere from 30 kilopascals to a few tens of megapascals ( from 0. 3 to a few hundred bar ), with some predictions that the comet would penetrate a layer of water and create a bluish shroud over that region of Jupiter.

In 1994, Galileo was perfectly positioned to watch the fragments of the comet Shoemaker-Levy 9 crash into Jupiter, whereas terrestrial telescopes had to wait to see the impact sites as they rotated into view.

By 6 August, when the Turkish siege was broken the comet had not been visible in either Europe or Turkey for several weeks.

" He might have had the comet tail phenomenon in mind when he wrote those words, although his publications on comet tails came several years later.

Peter Jenniskens had previously recognized that many of our meteor showers have no known active comet parent bodies.

Although he had suspected that two comets that had appeared in succession in 1680 and 1681 were the same comet before and after passing behind the Sun ( he was later found to be correct ; see Newton's Comet ), he was unable to completely reconcile comets into his model.

This calculation enabled him, after examining historical records, to determine that the orbital elements of a second comet which had appeared in 1682, were nearly the same as those of two comets which had appeared in 1531 ( observed by Petrus Apianus ) and 1607 ( observed by Johannes Kepler ).

JPL scientists confirmed that another impact event on Jupiter had occurred, probably a small undiscovered comet or other icy body.

Analysis showed the comet formed 4. 5 x 10 < sup > 9 </ sup > years ago from volatiles ( mainly ice ) that had condensed onto interstellar dust particles.

It had as its primary objective close flybys of two comet nuclei with the possibility of a flyby of a third known comet or an as-yet-undiscovered comet.

From these trajectory measurements, meteoroids have been found to have many different orbits, some clustering in streams ( see Meteor showers ) often associated with a parent comet, others apparently sporadic.

Some versions of the insignia include a comet in the top curve because of studies made of the Comet Kohoutek but these were not apparently worn during the flight.

This comet apparently made a substantial impression on the public, inspiring in some a fear that judgement day was imminent.

When the comet passed Jupiter in the late 1960s or early 1970s, it happened to be near its aphelion, and found itself slightly within Jupiter's Hill sphere.

* 1770 – Lexell's Comet passed closer to the Earth than any other comet in recorded history, approaching to a distance of 0. 0146 a. u.

Many thousands of years ago, a comet passed closely through the atmosphere of the earth, and deposited viral material that killed 97 % of the human race.

This cult was an ancient blood cult that passed on this genetic immunity to selective members to keep this antibody against the return of the comet ( which was set to happen in Season 3 ) so that they'd survive for being genetically select.

" Gurzadyan and Vardanyan argue that " Tigranes could have seen Halley's Comet when it passed closest to the Sun on August 6 in 87 BCE " as the comet would have been a " most recordable event "; for ancient Armenians it could have heralded the New Era of the brilliant King of Kings.

Indeed, on 19 May, the Earth actually passed through the tail of the comet.

For instance, comet Shoemaker – Levy 9's decaying orbit around Jupiter passed within its Roche limit in July 1992, causing it to fragment into a number of smaller pieces.

Comet Hyakutake (, formally designated C / 1996 B2 ) is a comet, discovered on 31 January 1996, that passed very close to Earth in March of that year.

Because the comet had probably passed close to the Sun several times before, the approach in 1996 would not be a maiden arrival from the Oort cloud, a place where comets with orbital periods of millions of years come from.

As the comet passed the earth, a large puff or blob of material was observed being ejected in the sunward direction every 6. 23 hours.

" Tigranes could have seen Halley's comet when it passed closest to the Sun on August 6 in 87, according to the researchers, who said the comet would have been a ' most recordable event '– heralding the New Era of the King of Kings.

* International Cometary Explorer — passed through gas tail of comet 21P / Giacobini-Zinner ( 1985 )

Tycho Brahe's investigations of a series of comets from 1577 to 1585, aided by Rothmann's discussion of the comet of 1585 and Michael Maestlin's tabulated distances of the comet of 1577, which passed through the planetary orbs, led Tycho to conclude that " the structure of the heavens was very fluid and simple.

He noted the comet passed very close to Jupiter during May 1912 and that, prior to this approach, the comet had a perihelion distance of 2. 15 AU and an orbital period of 9. 43 years.

On 26 October 1366, the comet passed from Earth.

Initial inspection revealed nothing, but in late 1968 she found a June 8, 1967 exposure ( Tempel 1 had passed perihelion in January ) that held the image of an 18th magnitude diffuse object very close to where Marsden had predicted the comet to be.

As the comet passed within 30 million km of the Sun, the nucleus was observed to split into four fragments.

Equally, Comet Hyakutake was a rather small comet, but appeared bright because it passed extremely close to the Earth.

As he is forcibly ejected from the room, a blue comet trail follows him ( i. e. " they passed ").

More exciting for planetary astronomers was that the best orbital solutions suggested that the comet would pass within of the center of Jupiter, a distance smaller than the planet's radius, meaning that there was an extremely high probability that SL9 would collide with Jupiter in July 1994.

However, although Schwarzschild's best known work lies in the area of general relativity, his research interests were extremely broad, including work in celestial mechanics, observational stellar photometry, quantum mechanics, instrumental astronomy, stellar structure, stellar statistics, Halley's comet, and spectroscopy.

The Rosetta probe, launched 2 March 2004, is planned to put a lander on comet 67P / Churyumov-Gerasimenko in 2014 ; due to the extremely low gravity of such bodies, Rosetta's landing system includes a harpoon launcher intended to anchor a cable in the surface and pull it down.

Based on these calculations, Heinrich Wilhelm Matthäus Olbers made a prediction that the comet would go on to become extremely bright later that year.

In many ways the comet was quite similar to Comet Hale-Bopp: it became spectacular without passing particularly close to either the Earth or the Sun, but had an extremely large and active nucleus.

A sungrazing comet is a comet that passes extremely close to the Sun at perihelion – sometimes within a few thousand kilometres of the Sun's surface.

An extremely bright comet seen by Aristotle and Ephorus in 371 BC is a possible candidate for this parent comet.

These 38th parallel structures are thought to possibly be the result of a serial impact, similar to that of comet Shoemaker-Levy 9 on Jupiter, an extremely unlikely event on Earth.

Sometimes, a comet failing on one criterion will still be extremely impressive.

For example, Comet Hale – Bopp had an exceptionally large and active nucleus, but did not approach the Sun very closely at all, yet it still became an extremely famous and well observed comet.

Subsequent orbital studies have determined that it was a Sungrazing comet, one which passes extremely close to the surface of the Sun.

The first comet whose orbit had been found to take it extremely close to the Sun was the Great Comet of 1680.

At this time of year, as seen from Earth, the comet would approach and recede almost directly behind the sun, and could only become visible extremely close to the sun if it became very bright.