The discovery of the Comet C/2013 A1 and its possible impact on Mars, The Chelyabinsk Impact on Feb 15 2013 (injuring over 1500 people) , The two comets Lemmon & PANstarrs gracing the southern skies in March 2013, the near miss by Asteroid DA2012 & the upcoming comet Ison (touted to be the Comet the century) in November 2013, poses a question ?

Is there an increased level of Comet & Asteroid activity and if so, is there a cause for this ?

It is a well known fact that our star, the sun, rises and falls through the Galactic plane every 35 to 4o Million years.  It has been theorized  that as it does so, interaction with nearby stars could be a cause of comets being flung into the inner solar system. However we are currently 2-5 millions into our journey OUT of the plane of The Milky Way and typical transit time into the inner solar system is perhaps Circa one million years.

So why are we apparently seeing more comets and asteroids now than at any time in the past ? The Chelyabinsk impact in Russia in February 2013 has only served to highlight concern about potential impacts on the earth by extraterrestrial bodies. Enough so, that both the US and Russian governments are now expanding the space search programs to look for these potential impactors.

The search for Asteroids has been steadily building since the invention of the telescope 400 years ago. That search has increased exponentially over recent years. Just 10 short years ago, when I co-founded Gove Astronomers in the Northern Territory, Australia, there was no effective program in the southern hemisphere for detecting NEO’s (Near Earth Objects). Now there is a world wide program in place intended to detect objects in the 100 metre plus range (high consequence impacts). This has routinely shown up NEO’s in the 20 to 50 metre class, which in themselves could cause local devastation.

So are there more meteors now that in the past, or are we simply more aware of then ? I think this simulation of Asteroid discovery from the 80’s to 2011 in part answers that question. (expand to full screen for best effect !)

So what about comets, are there more of them now than in the past ? Comet hunting has been popular among Astronomers, both professional and Amateur (unpaid) since the first telescopes fell into their hands. With the advent of the all sky surveys such as Linear, Neat and the most recent addition PANstarrs (Giving the name to the exciting comet of March 2013) & the SOHO discovery of sungrazers as they dive into the corona of the sun, the rate of early discovery has increased.

Anecdotal evidence would suggest the rate is increasing: As of January 2011 there are a reported 4,185 known comets of which about 1,500 are Kreutz Sungrazers and about 484 are short-period. This number is steadily increasing. However, this represents only a tiny fraction of the total potential comet population: the reservoir of comet-like bodies in the outer Solar System may number one trillion. (Wikipedia)

Conclusion:

While we are discovering and seeing more comets & asteroids now than at any time in the past, this is largely due to the increased rate of discovery, better equipment enabling more people to see faint comets, the pervasive availability of information online and of course the mainstream medias propensity for latching on the sensational stories & beating them up.

So could we be hit by a devastating comet or asteroid in our lifetimes ? Clearly the answer is YES.

Is this any more likely than at anytime in our past history ? Probably NOT.