A newcomet from the oort cloud, >10 km wide, has been discovered that is doing a flyby of Mars in October of 2014. The current orbit is rather uncertain, but it is probably passing within 100,000 km and the max likelihood is ~35,000 km. There is a tiny but non-negligable chance this thing could actually hit the red planet, in which case we would get to witness an event on the same order of magnitude as the K-T event that killed off the non-avian dinosaurs! (and lose everything we have on the surface of the planet and in orbit.)
I, for one, hope it hits. That would not be a once in a lifetime opportunity. That would be a ONCE IN THE HISTORY OF HOMINID LIFE opportunity! We would get to observe a large impact on a terrestrial body as it happened and watch the aftermath as it played out for decades!
As is, the most likely situation though is one in which we get to closely sample and observe the comet with everything we have in orbit around Mars. The orbit will be nailed down better in a few months when the comet comes out from the other side of the sun.
And to quote myself towards the end of the last open thread:
I don’t know if this has been brought up around here before, but the B612 foundation is planning to launch an infrared space telescope into a venus-like orbit around 2017. It will be able to detect nearly every earth-crossing rock larger than 150 meters wide, and a significant fraction down to a few at 30ish meters. The infrared optics looking outwards makes it much easier to see the warm rocks against the black of space without interference from the sun and would quickly increase the number of known near earth objects by two orders of magnitude. This is exactly the mission I’ve been wishing / occasionally agitating for NASA to get off their behinds and do for five years. They’ve got the contract with Ball Aerospace to build the spacecraft and plan to launch on a Falcon 9 rocket. And they accept donations.
I saw a mention of that elsewhere, but I didn’t realize that the core had a lower bound of 10km. Wow. I really hope it impacts too; we saw some chatter about the need for a space guard with a dinky little thing hitting Chelyabinsk, but imagine the effect of watching a dinosaur-killer hit Mars!
Different sources seem to have different orbital calculations, this one indicates a most likely close approach of ~100,000 kilometers with the uncertainty wide enough to include a close approach of 0 km.
If nothing else, we very well may get pictures from the surface rovers of the head of a comet literally filling the sky.
I am flabbergasted, I have no explanation for this situation.
If this comet is really that big and has approximately said flyby orbit, how frequent are those? If one every thousand years, there were 60000 of those since the TC event. How come we had only one collision of this magnitude?
Maybe they are less frequent. How lucky we are then to witness one of them right now? Too lucky, I guess.
As on the other hand, it looks we are just too lucky to have no major collision of that kind relatively recently, if they were quite common.
Maybe I am missing something odd. Like an unexpected gravity or other effect, by which an actual collision is much more difficult. Something in line with this. What makes sense, but only after a careful consideration.
Maybe a planet like Mars or Earth repels comets somehow? Dodge them somehow? Some weird effect like this?
I recommend Taleb’s The Black Swan. The major premise is that people tend to underestimate the likelihood of weird events. It’s not that they can predict any particular weird event, it’s about overall likelihood of weird events with large consequences.
Another way of stating it in this circumstance: there are so many different things that we would consider ourselves lucky to see or that we would notice as unusual that even if the probability of any one of them is low the probability that we see something isn’t that low.
If you are randomly shooting a rock through the solar system, “close approach of mars within 100,000 km” is 870 times as likely as “hitting mars”. That brings a ‘once in 100 million years (really roughly guessing based on what I know of earth’s geological history)’ event down to the order of ‘once in a hundred thousand years’, and the proper reference class of things we would be considering ourselves this lucky to see is probably more like ‘close approach of a large comet to a terrestrial body’ rather than singling out mars in particular. I don’t know enough about distributions of comet orbital energies to consider different likelihoods of comets having parabolic orbits that bring them closer to the center of the solar system versus further away to compare the odds of things going near the different terrestrial planets with different orbits.
The gravity of a planet actually slightly increases the fraction of randomly-shot-past-them objects that hit them over just sweeping out their surface area through space, but for something with a relative velocity of 55 km/s (!) that effect is tiny.
If so, we are indeed very lucky to observe an event, which happens every 100 000 years or so.
OTOH, I’ve conclude, that it is in fact less likely for a planet to be hit by a random comet than it is for a big massless balloon of the same size, to be hit by the same comet.
Why is that? Roughly speaking, if the comet is heading toward some future geometric meeting point, the planet will accelerate it by its own gravity and the comet will come too early and therefore flies by. It’s a very narrow set of circumstances for an actual collision to take place.
A bit counter intuitive but it explains why we have so few actual collisions, despite of the heavy traffic. Collisions do happen, but less often than a random chance would suggest. The gravity protects us mostly.
A new comet from the oort cloud, >10 km wide, has been discovered that is doing a flyby of Mars in October of 2014. The current orbit is rather uncertain, but it is probably passing within 100,000 km and the max likelihood is ~35,000 km. There is a tiny but non-negligable chance this thing could actually hit the red planet, in which case we would get to witness an event on the same order of magnitude as the K-T event that killed off the non-avian dinosaurs! (and lose everything we have on the surface of the planet and in orbit.)
I, for one, hope it hits. That would not be a once in a lifetime opportunity. That would be a ONCE IN THE HISTORY OF HOMINID LIFE opportunity! We would get to observe a large impact on a terrestrial body as it happened and watch the aftermath as it played out for decades!
As is, the most likely situation though is one in which we get to closely sample and observe the comet with everything we have in orbit around Mars. The orbit will be nailed down better in a few months when the comet comes out from the other side of the sun.
And to quote myself towards the end of the last open thread:
I saw a mention of that elsewhere, but I didn’t realize that the core had a lower bound of 10km. Wow. I really hope it impacts too; we saw some chatter about the need for a space guard with a dinky little thing hitting Chelyabinsk, but imagine the effect of watching a dinosaur-killer hit Mars!
For future reference, the JPL small body database entry on the comet:
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=C%2F2013%20A1;orb=1;cov=0;log=0;cad=1;rad=0#cad
Different sources seem to have different orbital calculations, this one indicates a most likely close approach of ~100,000 kilometers with the uncertainty wide enough to include a close approach of 0 km.
If nothing else, we very well may get pictures from the surface rovers of the head of a comet literally filling the sky.
I am flabbergasted, I have no explanation for this situation.
If this comet is really that big and has approximately said flyby orbit, how frequent are those? If one every thousand years, there were 60000 of those since the TC event. How come we had only one collision of this magnitude?
Maybe they are less frequent. How lucky we are then to witness one of them right now? Too lucky, I guess.
As on the other hand, it looks we are just too lucky to have no major collision of that kind relatively recently, if they were quite common.
Maybe I am missing something odd. Like an unexpected gravity or other effect, by which an actual collision is much more difficult. Something in line with this. What makes sense, but only after a careful consideration.
Maybe a planet like Mars or Earth repels comets somehow? Dodge them somehow? Some weird effect like this?
I recommend Taleb’s The Black Swan. The major premise is that people tend to underestimate the likelihood of weird events. It’s not that they can predict any particular weird event, it’s about overall likelihood of weird events with large consequences.
Another way of stating it in this circumstance: there are so many different things that we would consider ourselves lucky to see or that we would notice as unusual that even if the probability of any one of them is low the probability that we see something isn’t that low.
I second the book recommendation by the way.
Flabbergasted no more! There was no collision, of course.
Should have known it, immediately!
If you are randomly shooting a rock through the solar system, “close approach of mars within 100,000 km” is 870 times as likely as “hitting mars”. That brings a ‘once in 100 million years (really roughly guessing based on what I know of earth’s geological history)’ event down to the order of ‘once in a hundred thousand years’, and the proper reference class of things we would be considering ourselves this lucky to see is probably more like ‘close approach of a large comet to a terrestrial body’ rather than singling out mars in particular. I don’t know enough about distributions of comet orbital energies to consider different likelihoods of comets having parabolic orbits that bring them closer to the center of the solar system versus further away to compare the odds of things going near the different terrestrial planets with different orbits.
The gravity of a planet actually slightly increases the fraction of randomly-shot-past-them objects that hit them over just sweeping out their surface area through space, but for something with a relative velocity of 55 km/s (!) that effect is tiny.
Should we bring Shoemaker-Levy into this discussion?
If so, we are indeed very lucky to observe an event, which happens every 100 000 years or so.
OTOH, I’ve conclude, that it is in fact less likely for a planet to be hit by a random comet than it is for a big massless balloon of the same size, to be hit by the same comet.
Why is that? Roughly speaking, if the comet is heading toward some future geometric meeting point, the planet will accelerate it by its own gravity and the comet will come too early and therefore flies by. It’s a very narrow set of circumstances for an actual collision to take place.
A bit counter intuitive but it explains why we have so few actual collisions, despite of the heavy traffic. Collisions do happen, but less often than a random chance would suggest. The gravity protects us mostly.