-Geologic events that should take years or decades, at very least, take a few days.
-"Space junk" comes towards earth, imminent collision, and a response of thousands of nuclear warheads hit this object, yet do nothing.  Keep in mind if Jupiter were solid, we could blow it up with our nuclear stockpiles.

Aside from these inaccuracies, the human race always comes together with some hair brained idea to save the day, and it works.  The world has been brainwashed, so to speak, into believing that we are safe, but that isn't necessarily the case.  

There are many NEOs (near earth objects) floating around that we KNOW of, and many that we do not.  Comets interact with our orbit, and many objects have passed by the tiny rock we call our home, some recently.  Some were not discovered until they were millions of miles past us.  Other NEOs have been "predicted" to hit, yet miss (these may be interpreted as convenient schemes to build up a sense of security, or honest miscalculations).  The odds are undeniable; more objects will hit Earth.  Many already do, but are too small to be noticed, or fall outside of major populations.  Large NEOs are in space, and given enough time more will hit; given enough time, a doomsday object will hit.  The only uncertainty is when.

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Throughout scripture, the end of time is referenced.  Like each of our Earthly lives, it will come like a thief in the night, without our knowledge.  The end will be violent, with mayhem pouring down from the heavens.  The level of unpredictability and destruction parallels a NEO slamming into Earth.  A space object could slam into the Earth with little or no warning and cause disaster of biblical proportion.  Looking into the Revelation to John, many interesting possibilities are revealed.  (Please note that if you allow minute overlapping of the scriptures, it almost clarifies what could happen)

As the end is revealed to John, 7 seals are being broken by 7 angles.  In the first six scrolls plagues, death, and war are shown as things to come.  The sixth seal describes objects of the heavens coming down to earth.  Rev. 6: 12-16: 

"Then I watched while he broke open the sixth seal, and there was a great earthquake; the sun turned as black as dark sackcloth and the whole moon became like blood.  The stars in the sky fell to the earth like unripe figs shaken loose from the tree in a strong wind.  Then the sky was divided like a torn scroll curling up, and every mountain and island was moved from its place.  The kings of the earth, the nobles, the military officers, the rich, the powerful, and every slave and free person bid themselves in caves and among mountain crags.  They cried out to the mountains and the rocks. 'Fall on us and hide us from the face of the one who sits on the throne and from the wrath of the Lamb, because the great day of their wrath has come and who can withstand it?'"

The sun blacking out can be explained by a solar eclipse, a shrouding by space dust/medium sized space particles, or could it be from a large object coming from the direction of the sun, blocking sunlight just before impact?  With light interactions with a shroud of relatively small space particles, the moon could be "illuminated" red.  Stars falling to earth could be a meteor shower; many "falling stars" streaking through the sky.  The sky being divided like a torn scroll is strikingly similar to what a large object flying thru the atmosphere would look like (think of the images from 'Deep Impact').  The impact of such a large object could obliterate mountains, and create massive tsunamis that could crash upon islands and costal regions with a fury never before seen.  In the aftermath of an event of this magnitude, the surviving people of the world would definitely be clinging to life in the rubble of whatever may be around.  In the immediate aftermath of such a strike on the Earth, earthquakes and volcanic eruptions would ravage the entire face of the planet.

More can be drawn from Revelations when angels are blowing the seven trumpets.  In Rev. 8, incense is offered to God, and an angel took burning coals from the altar and threw them down to earth.  This could be more debris falling to Earth, possibly large enough to make it to the ground.  Later in chapter 8 it says, "There were peals of thunder, rumblings, flashes of lightening and an earthquake."  The peals of thunder and rumblings can be related to objects falling to earth, for they will not be quiet.  The first angel who blew his trumpet brought hail mixed with blood that burnt up a third of the land, trees, and grass, much like the fires would spread throughout the land after such an impact with Earth.  When the second angel blew his trumpet, "something like a large burning mountain was hurled into the sea.  A third of the sea turned to blood, a third of the living creatures in the sea died, and a third of the ships were wrecked."  Could this be another object from space high in iron content that created waves and poisoned the creatures of the sea?  Could this be the rupturing of a mid ocean volcanic rift?  Both would be red, though an object full of iron would tint more of the waters, and iron is what makes our blood red.  

With later trumpets a third of the sun, moon, and stars were "struck" so that a third of them became dark.  The dust and debris thrown into the air would circle the globe and act like tinting for the whole world, allowing only a fraction of the normal light through to the surface.  Another trumpet yielded a third of the rivers and springs of water killed people because it turned bitter.  The water sources of Earth would become poisoned because of the ash spewn into the sky from the space objects.

Coming now to the fifth trumpet, John states that he has seen a star that had fallen from the sky to the earth.  "It opened the passage to the abyss, and smoke came up out of the passage like smoke from a huge furnace.  The sun and the air were darkened by the smoke from the passage."  When a large object strikes Earth, out of its crater comes a spire of debris and smoke, just as described in the above passage, darkening the sun and air (The impact in Armageddon).  After this locust come out and sting those who do not have God's seal like they were scorpions.

The sixth trumpet was blown, and a third of the human race is killed by the four angels who were bound to the banks of the Euphrates River.  Then an angel with a small scroll says that at the blowing of the seventh trumpet, God's mysterious plan will be revealed, as promised to the prophets.  It is said that the holy city will be trampled for 42 months.  For three days the corpses will be displayed, not allowed to be buried.  Then signs appear in the sky, and God's plan is continued to the end.

This is undoubtedly a lot of information to absorb, and these passages will have different meanings to different people, though much is revealed.

Correlating the scripture with known scientific information, Revelation points out various occurrences in detail.  Rearranging the order yields this:  The sun is darkened and eventually becomes black.  Stars fall from the heavens with a great fury, and in the midst of this a large "star" falls to Earth, possibly another hitting the sea.  Widespread destruction occurs.  Smoke, ash, and debris fill the sky blocking a substantial fraction of light, much water is poisoned.  Mountains crumble, islands are swallowed up, earthquakes rumble as volcanoes become more active than present.  The remaining people on Earth cling to life in the rubble that was once their home and civilization.

This information has been given, and with increasing scientific knowledge new ideas can be created to explain how the end might occur.  Even so, there is no point in having this knowledge of destruction and recognizing the utter uncertainty of when it will happen, if nothing is done in heed of it.  As hard as the government and NASA may try, they will not be able to stop God's fury.  This does not mean disasters cannot be avoided, but when God says it's time, the end will come.  No warning will be given to humanity.  There will not be a given timeline humanity will have to straighten itself out.  Already sunlight readings around the globe are slowly declining with no known cause.  Only God knows, but the end may be nearer than we think.  If the end were to come tomorrow, would you be ready?