It's still unclear when the government found out, or which government for that matter. But with hindsight it becomese apparent what must have been happening for years. Silent hands were working behind the scenes, putting the pieces into place around the world long before The Event took place. About one year before it happened, rumors began circulating amongst the general public. Amateur astronomers, bloggers, conspiracy theorists and assorted crackpots were the first to take up the call. This created a minor stir, but was mostly buried in the noise of TV and the internet. When scientists and university professors began independently confirming the reports, more established news outlets started carrying the story. It didn't take much longer for all hell to break loose.
Piecemeal accounts regarding the preparation being conducted by governments around the world were being put together by various investigative reports. Resources were being stockpiled, regional conflicts made more acute and long-standing and new rivalries were flaring into unprecedented violence. Governments were spending more and more money on so-called "black programs". Those in the know were preparing for the worse. Those not were struggling to comprehend a New World Order.
The official silence was at first deafening. When it became clear that the story wasn't going away, the typical response shifted from silence to active denial. But the truth was too terrible and too awesome to hide for long. It was to be the event of the millennium, perhaps of all recorded human history. An extra-terrestrial object the size of a small country was on a collision course for the Earth at a velocity difficult to attribute to a natural object. Life on the planet as it was known up until then was about to irrevocably change and possibly end altogether.
A comprehensive unraveling began as grave reality came into focus. Worldwide financial collapse was followed closely by widespread anarchy and war. Doomsday and UFO cults sprung up overnight and their ranks swelled. More traditional faith groups doubled and trebled their number of active members. Church pews strained under the weight of pleading and penitent humanity. Reports of mass suicides, military coups, food riots and clandestine government activity replaced celebrity tweets and sex scandals as news fodder. Sightings of UFOs, the Virgin Mother, Shiva, The Four Horsemen, Buddha, Al-Mahdi and Elvis became so common place that they stopped being reported, even ironically, all together. The world, never a particularly kind place, had suddenly become a much more serious and chaotic one.
Weaker governments folded altogether while the stronger ones clamped down harder on their populaces. A nationwide State of Emergency was declared in America days after several E.U. countries, led by a frantic German chancellor, did the same. The U.S. borders were closed and within a month martial law declared. Local and state governments and agencies were consumed by federal agencies. Some, like Texas and a few New England states, resisted. These "rebellions", as they were characterized by elements of congress and the president, were put down quickly and with what many mostly silent critics considered disproportionate violence. These , however, paled in comparison to atrocities committed around the world. Life on Earth was changing rapidly and for the worse.
As the whole world shuffled frantically toward imminent doom, something unexpected happened. The celestial object that hurtled toward the planet at unimaginable speeds shifted course. Weeks before it would have struck the planet and ushered in another mass extinction it simply turned subtly upon a new course taking it through the solar system but away from Earth. The world held its breath for several days as the object rushed past the planet, then beyond the sun and the reach of the shorter-range senors scrambled up into high orbit to study it.
The world had survived, but had irrevocably changed in ways that would not be understood for years after The Event and perhaps never at all. Nothing could be the same as it was before. Not ever again.