Welcome to the real world
As a few have said here on this thread, this is not unusual. The truth of the matter is that we live in a "cosmic shooting gallery", and the threat
of an impact is more a matter of "when" than "if".
Nothing has changed, apart from our ability to detect potentially hazardous objects, and as more are discovered, the general public which is not used
to having to deal with what the media has branded an "end of world" type scenario, is bound to become concerned.
Whilst impacts do occur from time to time, and "near-hits" are quite common place, the chances of an impact that is powerful enough to threaten
human life or our society is very low in the short term. Don't forget, man has been around for many thousands of years, despite more or less constant
bombardment from the skies.
Of course, no one can predict with 100% certainty that the next discovered PHO will not be a global killer, but from the past record of
encounters/observations it's clear that such objects are relatively few and far between, and when they do pass by, it's usually not even close to a
I think many people also have a false perception of what is considered "near". For instance, let's say that the Moon-Earth system is represented by
a dart-board. With the area of the Earth represented by the bull's eye, and the ring of double-score's around the outside would be roughly
representative of the distance to the Moon's orbit. If you picture this, and I think it's even an under representation of just how much empty space
there is in the Earth-Moon system, then imagine throwing a dart. It's not all that easy to hit the bull's eye, even when you're aiming for it!
Statistically, major impacts that have world-wide repercussions occur roughly once every 10,000-30,000 years (off the top of my head), and these are
the objects that we should be wary of and prepare for. Indeed we are overdue already for the next big one, but it could be another 5,000 years before
it comes along. There is no point worrying about it in the mean time. If it was due tomorrow or in two years time, there would be little we could do
about it. We do need to start looking seriously at ways to protect ourselves in the long term though.
reply to post by SlightlyAbovePar
Yes - this is pretty much true. It's harder to spot the smaller objects, and there is not much point in trying to track smaller objects that are
incapable of causing significant damage to us. It's much better to concentrate our resources looking for the objects that can cause major devastation
on a continental or global scale.
To be blunt, there are many PHOs, that are capable of destroying a city, but the chance of a city being hit is low - 2/3 of the world is ocean, and
only a tiny area of the remaining 1/3 is densely inhabited. To be even blunter, cities are expendable, though I'm sure the loss of one would be
The angle of approach is also a potential worry as you say. The problem is that much of the sky is not monitored due to lack of funding. The biggest
gaps are in the Southern sky, and the sky close to where the sun is, since in the sun's glare we are incapable of spotting "smaller" objects until
they have passed us already.
There have been proposals to plug these holes, using a network of telescopes in the Southern hemisphere, and launching a space-based platform to sit
in a position where it can monitor the part of the sky which would normally be impossible to monitor because of the sun's glare, but as far as I'm
aware, there is no funding so far for these projects.