|
Current comet status: Fading.quote:Comet PanSTARRS (C/2011 L4) peaked at roughly magnitude +1 and is now fading with a widening tail, low in the western evening twilight for observers at northern latitudes. It's certainly not the spectacle we once hoped for — but it's there. http://www.skyandtelescope.com/obse.../185665152.html  http://blogs.scientificamerican.com...northern-skies/ --------------------------- OP vv This year we are getting some quite interesting visitors to the inner solar system. Two comets, unassumingly named C/2011 L4 and C/2012 S1, are emerging from eons of frigid silence to put on the show of their life. It might be the only chance they get! As with most space subjects, Wikipedia is fantastic in describing it, but let's sort out some basics here: What is a comet?  A dirty snowball is often used to describe comets. Ice, rock, dust, gravel, stuff like that. The ice can be water, but also ammonia, carbon dioxide and other things that only form ices when it's really nippy out. When these ices get heated by the sun, they turn to gas and escape from the comet, forming its familiar shape. The coma is like an extremely thin atmosphere, a ball of gas around the nucleus. Then there's the tail, which is material dragged away from the comet by the solar wind (which means the tail always points away from the sun). Comets can vary in size from a football field to a large city, but the tails can stretch for millions of miles.  C/2006 P1 aka Comet McNaught. How come they come and go at weird intervals?  They have very different orbits. In general they are divided into short period and long period. Halley's Comet, perhaps the most famous one, is a short period comet. It takes about 76 years to orbit the sun, which is about half the time Neptune uses to do the same. However, unlike Neptune's nice and orderly circular orbit, Halley's comet like many other comets has a very eccentric orbit - this basically means that there is a big difference between the shortest and longest distance from the sun - perihelion and aphelion in spacespeak. It orbits in an elongated ellipse:  With some patience you can see it speed up when it nears the sun and then slow down as it heads out. Its aphelion is about 35 AU, near Neptune's orbit while its perihelion is about 0.6 AU - 1 AU being the distance between the Earth and the sun. If you want to play around with orbits to get a feel for how they work, this little flash thing is helpful: http://www.windows2universe.org/phy...nteractive.html Long period comets also have eccentric orbits, but where short period comets take less than 200 years to complete an orbit, long period comets can take thousands, even millions of years. Their aphelia are far outside the planetary orbits, but their perihelion can be as close as Halley's, or closer. For a hundred thousand years they can be lurking in complete silence and darkness, invisible to even the most powerful telescopes. Then as they come into the solar system, the radiation from the sun starts cooking off the ice, they speed up and come thundering onto center stage with their hair on fire. Then after they swing around the sun, it's back out into the cold for another hundred thousand years. Then there are the non-periodic comets. Their orbits are so eccentric that it's no longer an orbit. It's simply a trajectory that is bent by the solar gravity and then they are spat out into the void. They might originate in the mysterious Oort Cloud, a vast (almost a light year across) but wispy thin sphere of dust, ice, gases and rocks. It might be the expanding remnants of the creation of the solar system or more fundamentally, different parts of the cloud of stuff from which the solar system was created. Gravitational forces from the solar system or from other stars might nudge one rock slightly out of its orbit which in turn might eventually send it towards the Sun. And when these bad boys come sailing in, they are really screaming. Adding to the drama of their massive speeds, the ice in them might never have been exposed to heat before. So a virgin comet fresh out of the Oort cloud passing very close to the sun might be a very spectacular show indeed.  Comet Kohoutek, also known as the shittest comet of the century. It was theorized it would put on a big show, but after massive media hype it petered out in a small puff.  Can they hit Earth? They sure can. In fact, it's very probable that one did in 1908, causing the Tunguska event. This was an atmospheric explosion over Siberia, the size of a large hydrogen bomb, which flattened 80 million trees. And that was probably a small one. You might remember Comet Hale-Bopp, which was used by an evil weirdo to cause mass suicide. Its diameter was around 22 miles and the force of its impact would have been 44 times greater than the asteroid which is hypothesized to have killed the dinosaurs. Our poo poo would have been well and truly hosed up. However! Fear not. The visitors of 2013 are not going to hit Earth. So anyway, what's with the boring names? Well that's just the system the science people use to catalog them, based on their type and time of discovery. Let's take C/2011 L4. C - a non-periodic comet (periodic ones are called P) 2011 - year discovered. L - half-month discovered. A = early January, B = late January etc. L = late June. 4 - the fourth C-type object discovered in that period of time, i.e. the two last weeks of June 2011. They sure find a lot of them huh? Only periodic comets get names and even then it's just the names of the person(s) who discovered them. Luckily astronomers have pretty cool names. Shoemaker-Levy. Hale-Bopp. Swift-Tuttle. Kohoutek. Sounds very spacey. I think the astronomical society should have a lottery and the winner gets to pick the name of a non-periodic. My top three comet names: Thunderpunch. Testicles (pronounced "Testiclees" like Aristoteles). And Bob the Space Dog. Great names. Thanks. What were the names of the ones visiting us again and when are they coming? Right, so the offical names are C/2011 L4 and C/2012 S1, but they have been referred to by the names of the observatories that discovered them, respectively Pan-STARRS and ISON. Those are pretty cool nicknames, so let's use them. The first visitor is C/2011 L4 Panstarrs and it's only a month away! Its closest pass to Earth is on March 5, its perihelion is on March 10 at 0.3 AU (same distance as planet Mercury). It's predicted to be about as bright as Venus, which means it's visible to the naked eye but might be lost in the glare of the sun. The brightness is very hard to predict though, it all depends on how much material it ejects. As comet hunter David Levy (as in Shoemaker-Levy 9, the one that hit Jupiter) says: Comets are like cats; they have tails, and they do precisely what they want. Clever cat quote and more details available here: http://earthsky.org/space/comet-pan...e-in-march-2013 Then the big show. C/2012 S1 Ison should be visible from late summer, its perihelion is on November 28 at a staggering 0.012 AU. That's less than one solar diameter above the surface of the sun! If you consider that this might be a fresh comet that has never thrown a tail before, you can imagine that this might be some fantastic fireworks. "Comet of the century" has been carefully whispered by some...they remember the Kohoutek disappointment. Remember, they do what they want. So don't be let down if it's not a vast streak across the night sky, it's an amazing enough thing to consider that this weird little snowball is careening into our front yard from the icy void only to get kicked out by the sun, possibly never to return again. I know there are quite a few amateur astronomers on SA, hope you can get some pictures for us! I'll update this post with pics as they come in.   Source: http://www.aerith.net/index.html Ola fucked around with this message at Mar 24, 2013 around 16:47 |
| # ? Feb 5, 2013 10:39 |
|
|
|
| # ? May 19, 2013 11:17 |
|
|
This is a great post. Thanks OP. I know as a kid I would hear about that death meteor that was supposedly going to wipe out the earth and that, supposedly, in the past killed off the dinosaurs. Used to scare the heck out of me.
|
| # ? Feb 7, 2013 00:51 |
|
|
Wikipedia on comet ISON posted:In November, when the comet is brighter, it will sweep another bright star in our sky, Spica in the constellation Virgo, and another planet, Saturn.[13] Around the time the comet reaches its perihelion on 28 November, it may become extremely bright if it remains intact, probably reaching a negative magnitude.[5] It may briefly become brighter than the full Moon.[7][8]  Thanks for this thread OP. Every time something like this pops up I get to thinking about the scale of the universe and my brain just can't after a while.
|
| # ? Feb 7, 2013 01:14 |
|
|
Here's a video of ISON taken by the Deep Impact probe. Looks like an old-timey sci-fi movie! http://www.youtube.com/watch?v=pv7x1H1b9MA
|
| # ? Feb 7, 2013 01:24 |
|
|
I remember a while ago there were like 3 or 4 or maybe more meteors(?) that hit, I thought Saturn (though I could be wrong) all in a row. They were lined up and hit the planet one at a time and left a scar on the planet. Anyone have a link to the wiki on it since when I look up Saturn meteor impact it doesn't show so I must have gotten the planet wrong. (or dreamt it).
|
| # ? Feb 7, 2013 01:26 |
|
|
Morally Inept posted:I remember a while ago there were like 3 or 4 or maybe more meteors(?) that hit, I thought Saturn (though I could be wrong) all in a row. They were lined up and hit the planet one at a time and left a scar on the planet. Anyone have a link to the wiki on it since when I look up Saturn meteor impact it doesn't show so I must have gotten the planet wrong. (or dreamt it). It was Shoemaker-Levy 9, and it hit Jupiter.
|
| # ? Feb 7, 2013 01:31 |
|
|
It was Jupiter and they were the Shoemaker–Levy 9
|
| # ? Feb 7, 2013 01:39 |
|
|
Great thread! Just a couple weeks ago I was thinking that there hadn't been any good comets lately, and was pretty psyched to find that we are actually having two really awesome ones this year. Anyway the best thing about comets is that you don't need a big telescope to see them. Just an area away from bright lights. Having binoculars or a low magnification telescope can bring out a lot of neat detail though. The other cool thing is that you can get nice photographs with just a fast lens and a tripod. DSLRs work great and even compact cameras can get good results if you can adjust the exposure long enough.
|
| # ? Feb 7, 2013 01:47 |
|
|
In addition to Shoemaker-Levy 9, there were impact events recorded on Jupiter in 2009, 2010, and 2012. All of these were discovered by amateur astronomers.
|
| # ? Feb 7, 2013 01:55 |
|
|
I read the OP but i might be dumb, so are these comets going to be visible with the naked eye and if so, when and in which hemisphere.
|
| # ? Feb 7, 2013 02:09 |
|
|
Very (cautiously) excited for this. I remember seeing Hale-Bopp as a kid, and drat I'd love to relive the experience. Also have had the pleasure of seeing David Levy speak at a Star Party in my area. Once the fireworks start I'll for drat sure have to get my scope out and try and get some pictures. Cool note on Shoemaker-Levy 9. The impact event made a lot of politicians realize the same thing could happen to earth, and we now have the Near-Earth Object Project.
|
| # ? Feb 7, 2013 02:10 |
|
|
ol qwerty bastard posted:Here's a video of ISON taken by the Deep Impact probe. Looks like an old-timey sci-fi movie! Yep, it needs some overly dramatic piano accompaniment. edit: that's more like it.
|
| # ? Feb 7, 2013 02:13 |
|
|
Nichelle Nichols (Uhura from Star Trek) brother was a member of the heavens gate cult and killed himself and now he lives on a comet.
|
| # ? Feb 7, 2013 04:25 |
|
|
PlantRobot posted:Yep, it needs some overly dramatic piano accompaniment. I wasn't expecting it to be THAT good but 
|
| # ? Feb 7, 2013 06:33 |
|
|
Ola posted:Then there's the tail, which is material dragged away from the comet by the solar wind (which means the tail always points away from the sun). I always thought it was stuff trailing behind the comet.
|
| # ? Feb 7, 2013 06:39 |
|
|
Spectral Debt posted:I read the OP but i might be dumb, so are these comets going to be visible with the naked eye and if so, when and in which hemisphere. The wiki-pages explain pretty well: http://en.wikipedia.org/wiki/C/2012_S1 http://en.wikipedia.org/wiki/C/2011_L4 But the short version is that they will be near the sun, so any place that can see the sun can see the comet. The problem with that is that they will be lost in the glare, with the best viewing near sunset or sunrise. Their orbits have inclinations of 62 and 84 degrees...I may be completely wrong here, but to me it seems to mean that they are coming up from below so to speak, flying up towards the plane of the solar system at a pretty steep angle. I wish I knew enough about this to be able to set up a planetarium simulation so I could find out the best times for viewing it. Regardless of how it turns out, I have plans of bringing a bottle of wine, camera and tripod and hike up into the hills above my town for a great view of the setting sun in the west.
|
| # ? Feb 7, 2013 12:43 |
|
|
You take the letter t out of cometwatch and the thread title turns into a pretty disgusting notion. Aside from misreading the thread title, nice OP you did there.
|
| # ? Feb 7, 2013 14:11 |
|
|
What's the easy way to get these imported into Stellarium? EDIT: OK, latest version is a lot easier than before. In the past you had to export the comet in MPL format, put it in a .ini file, and then hope Stellarium reads it. Now, you just click through the GUI. It's about 5-10 steps, and you can tick C/2011 L4 and C/2012 S1 off the list. Add. You're done! 
kimihia fucked around with this message at Feb 7, 2013 around 15:10 |
| # ? Feb 7, 2013 14:30 |
|
|
Spectral Debt posted:I read the OP but i might be dumb, so are these comets going to be visible with the naked eye and if so, when and in which hemisphere. First, we don't know for sure because it's very hard to predict. Basically, a comet is a giant ball of ice and dust, and as it approaches the sun, that ice and dust start boiling off. There more stuff flies off, the brighter it is going to be. However, we just don't know what's going to happen. The first comet, usually called Pan-STARRS, is looking to be a bit of a disappointment, but it should eventually brighten up to be 2 or 3 magnitude. This is about as bright as the main stars of the Little Dipper. Right now it is visible from the Southern hemisphere, but it is heading upwards, and after it passes the Sun it will be visible in the Northern hemisphere. That happens on March 10th, and that's when it will be the brightest. You'll want to look to the West just after sunset. The second comet, ISON, has the potential to be incredibly good. That one will be visible in November/December/January. This one might actually be visible in the daylight, although it will be very close to the sun and probably be hidden somewhat by the sun's glare. Once it moves a little away from the sun it should be visible after sunset and be quite bright. It makes its closest approach to Earth in January and the tail could stretch over a good portion of the sky at that time.
|
| # ? Feb 7, 2013 17:52 |
|
|
Bold Robot posted:
Technically it is, but since the only wind in space is always coming out of the sun, it always makes the tail point away from the sun. Imagine the comet is a car with a bunch of snow on top, traveling down the road with the wind at its back. If the car is moving slower than the wind, the snow is going to blow off to the front of the car  Don't feel bad though because it's one of the most common space misconceptions.
|
| # ? Feb 7, 2013 18:02 |
|
|
The reason Panstarrs is shaping up to be an underperformer is because it's a first-time visitor from the Oort Cloud. These first-timers usually have a layer of volatiles on their surface that make them brighter than a returning comet at the same distance further out from the sun. As they close in on the sun the surface volatiles run out and it ends up not brightening as much as originally expected. This is also why Kohoutek ended up being a dud. Most observations I've read so far have suggested that the surface volatiles have already burned off, so 2nd or 3rd magnitude is probably the best we're going to get...and probably only a 3rd or 4th magnitude comet by the time it gets out of twilight and is easily visible. Still better than nothing, though, since naked eye comets are still kind of rare, and the last one I remember seeing was McNaught 6 years ago. I'm not sure how well Ison will hold up, since I haven't heard whether or not it's on an elliptical or parabolic orbit yet. If it's on a parabolic orbit, the same caveats that apply to Panstarrs will probably apply here. It will get a little brighter than Panstarrs though, since it will be approaching a lot closer to the sun. If it's elliptical, well, all bets are off and it is probable that it will become one of the most spectacular comets in recorded history. Also of note this year is Comet Lemmon (discovered last March by the Mt. Lemmon observatory) which is currently putting on a good show in the southern hemisphere. It's 7th magnitude and still brightening. It will continue to brighten to a maximum of 2nd or 3rd magnitude in late March, although it won't be visible to us northerners until early April. Will probably still be putting on a respectable show, though. EDIT: stupid phone I didn't tell you to put a break there EDIT 2: Now that I think about it, Comet Holmes had its spectacular outburst after McNaught came by so there's been at least one naked eye comet for the north since then. Venusian Weasel fucked around with this message at Feb 7, 2013 around 18:40 |
| # ? Feb 7, 2013 18:18 |
|
|
edit: ^^ excellent info Venusian Weasel! kimihia, thanks for the Stellarium info! I'd like to have a go at predicting some simple stuff (when will the moon be visible out of my living room window?) and it looks like the right tool. And thanks everyone for positive feedback on the OP. I'm glad the basics taught someone some new stuff, hopefully we'll all be a lot more clever about comets at the end of this year. On that note.. evensevenone posted:First, we don't know for sure because it's very hard to predict. I'll expand a tiny bit on this. As evensevenone says, their visibility is very hard to predict, it depends on how much stuff the comet disperses which in turn sunlight can reflect off of. But the position of the comet can be calculated with incredible accuracy. That's one of the things that are so fascinating about stuff in space. The rules that govern their movements and the factors that influence them are so simple (relatively speaking) that it's not a big deal predicting the movements. All solar eclipses 10,000 years in the future or the exact path of a space robot sent to explore the outer solar system, easy peasy for the people that know how. As for the tail which points away from the sun, the pic in the OP is a good illustration: You see the sun setting, so you know where the sun is. And you can see the lines in the tail radiating away from the sun, showing you were the tail pointed when the comet was there. Yet the stuff stays behind, it doesn't blow away with the speed of the solar wind - just like snow doesn't necessarily blow away with the speed of the wind, if it's heavy enough. So the comet throws a skidding pattern on the sky, it reminds me of a rally car sliding on dirt. Its tires kick up dirt in one direction but the car moves in another, causing the dirt to fan out. Or perhaps someone waving a roman candle in the air. The flame always shoots along the axis of the candle, but the stuff expelled draws an arc as you wave it around. Looks pretty  actually.edit: everyone's skeptical about Panstarrs lately, I'm a believer. Go on you little scamp, show them what you've got! Ola fucked around with this message at Feb 7, 2013 around 18:33 |
| # ? Feb 7, 2013 18:30 |
|
|
Odoyle posted:I wasn't expecting it to be THAT good but That music seems to fit nicely with ominous space videos... Exhibit B. Fister Roboto posted:Technically it is, but since the only wind in space is always coming out of the sun, it always makes the tail point away from the sun. Imagine the comet is a car with a bunch of snow on top, traveling down the road with the wind at its back. If the car is moving slower than the wind, the snow is going to blow off to the front of the car I don't mean to confuse the issue but comets can and often do have more than one tail, for various reasons: ThinkQuest posted:A comet may have one of two types of tail, and many comets have both types--a double tail. One is elongated and almost straight, has a fibrous structure, and consists of ionized gases. This type of tail is called a Type I tail, a gas tail, or a plasma tai l. Type II tails, or dust tails, are more strongly curved and hazier; they consist of dust repelled by sunlight. A comet may possess several dust tails in addition to a gas tail. Some comets have an anomalous tail, or antitail, which points toward the Sun (for example, the Arend-Roland comet, 1957 III). The antitail is a very thin layer of dust expelled at an earlier stage and lying along the orbit of the comet. The gases that predominate in the tail are ions th at, like those in the coma, are formed when larger molecules are split by the solar wind.  And the Great Comet of 1744 had six! Handen fucked around with this message at Feb 9, 2013 around 20:40 |
| # ? Feb 9, 2013 20:28 |
|
|
Handen posted:And the Great Comet of 1744 had six! I'm going to work on a visual observation post sometime tonight or tomorrow about useful information amateur astronomers can contribute even if they don't have cameras. It'll cover the types of observations and how to make them. I used to do that kind of stuff before I got busy in college, but I've still got a lot of the how-tos bookmarked on my computer. To those interested in watching for comets: go ahead and start learning the sky! If you have a telescope, start practicing astronomical sketches! A good target to do this is the Great Nebula in Orion, well placed after nightfall. There's lots of fine details there that will train your eye to look for interesting things when these comets are at their brightest.
|
| # ? Feb 9, 2013 21:04 |
|
|
Anyone planning to see 2012 DA14? It's only an asteroid. Can we talk about it in the comet club? http://www.theregister.co.uk/2013/0...n_on_2012_da14/
|
| # ? Feb 14, 2013 01:37 |
|
|
kimihia posted:Anyone planning to see 2012 DA14? It's only an asteroid. Can we talk about it in the comet club? I'd assume it's okay, there's not a whole lot else going on. Also sorry for the lack of info posting, I'm still working on the how-to comet observation guide. EDITL vv sadly I'm in North America so I get the disappointment of not being able to see it until well after closest approach. If anyone's interested in catching this one, I'd suggest maybe trying to track some of the fainter satellites through binoculars in the morning or before the approach tomorrow evening, it should at least give a little practice at spotting faint moving objects. Venusian Weasel fucked around with this message at Feb 14, 2013 around 03:45 |
| # ? Feb 14, 2013 01:39 |
|
|
kimihia posted:Anyone planning to see 2012 DA14? It's only an asteroid. Can we talk about it in the comet club? It won't be visible to the naked eye unfortunately (predicted to peak at 7.2 magnitude). It'll be observable with a telescope or large binoculars from Southern Asia and Australia but it'll be moving pretty quickly and you'll need to play around with this http://ssd.jpl.nasa.gov/horizons.cgi to figure out where it will be given your location. Standard astronomical software can't map it's trajectory accurately because Earths gravity will be changing it's orbit. Here's some more info: http://astroguyz.com/2013/02/09/ast...-asteroid-da14/ The cool thing is that if you do find it you should be able to see it moving against the starfield, it's that close and moving that fast.
|
| # ? Feb 14, 2013 01:55 |
|
|
I just got my hands on a pair of Celestron Skymasters and plan on having a hunt for 2012 DA14 early saturday morning. I used this website http://www.heavens-above.com to generate a flight path for my location. Here in South Australia it should be traveling just over the top of Crux at about 4:30 in the morning.
|
| # ? Feb 14, 2013 03:09 |
|
|
Asteroid mining is gonna own. There are currently two companies with plans to launch by 2020, and NASA has the awesomely named OSIRIS-Rex program in the works too. Here's one company's mock-up of a "Dragonfly" asteroid-hunting drone 
|
| # ? Feb 14, 2013 04:05 |
|
|
EpicPhoton posted:Very (cautiously) excited for this. I remember seeing Hale-Bopp as a kid, and drat I'd love to relive the experience. You and me both. COOL STORY BRO: My 9th birthday coincided with a local star party that took place less than a week after perihelion. It was amazing. The end.
|
| # ? Feb 14, 2013 04:19 |
|
|
Speaking of DA14, I know scientists are 99.99999% sure it will miss us, but what would happen if it did hit? Wikipedia compared it's size/velocity to being equivalent to Tunguska, so if it did hit, while being catastrophic to nearby cities, would it even be strong enough to cause a mass extinction event? I'm not really worried about it or anything, but I still find myself curious.
|
| # ? Feb 14, 2013 04:41 |
|
|
BlazinLow305 posted:Speaking of DA14, I know scientists are 99.99999% sure it will miss us, but what would happen if it did hit? Wikipedia compared it's size/velocity to being equivalent to Tunguska, so if it did hit, while being catastrophic to nearby cities, would it even be strong enough to cause a mass extinction event? I'm not really worried about it or anything, but I still find myself curious. Well, Tunguska didn't cause a mass extinction and wasn't even major enough of an event to have been investigated for years, so this one wouldn't be a world-ending event. But yeah, if it hit a population center, that'd be a bad thing.
|
| # ? Feb 14, 2013 04:43 |
|
|
DA14 is probably very similar to the asteroid that produced Meteor Crater, which was a ~50 meter nicker-iron object. If it entered over land it'd hit and gouge out a crater, but nothing more. Sucks if you're directly underneath it, but a person could be quite close to ground zero and survive. (Of course a direct hit on a population center is a disaster, but the chances are tiny.) Tunguska is not a great example because even though the overall impact energy is very close to that of Meteor Crater, the airburst spread that energy much more effectively. Instead of a 1km crater you get an 8km zone of flash-burned upright trees and a 70 by 55 km area of knocked down trees. A nuclear weapon is detonated in the air for the same reason; energy that goes into digging out a crater is wasted. So, if a 50 meter object is coming down in your vicinity, you should hope it's a strong chunk of metal and rock and not a loosely aggregated asteroid or comet.
|
| # ? Feb 14, 2013 12:36 |
|
|
Here is Bill Nye explaining what would happen if it hits.
|
| # ? Feb 14, 2013 13:04 |
|
|
What would happen if it did connect with earth, but landed out in the middle of the ocean somewhere far from land? Basically nothing as far as the world as a whole is concerned, or would it make a tidal wave or what?
|
| # ? Feb 14, 2013 14:57 |
|
|
mr. nazi posted:What would happen if it did connect with earth, but landed out in the middle of the ocean somewhere far from land? Basically nothing as far as the world as a whole is concerned, or would it make a tidal wave or what? Surf's up, dude! Kowabunga! There's a fiction book called Lucifer's Hammer (Larry Niven?) that's a decent read about a comet smacking into the earth. One scene describes some hodads riding a totally gnarly wave (like 400 feet high) caused by ocean impact.
|
| # ? Feb 14, 2013 15:44 |
|
|
mr. nazi posted:What would happen if it did connect with earth, but landed out in the middle of the ocean somewhere far from land? Basically nothing as far as the world as a whole is concerned, or would it make a tidal wave or what? A very rough scale of impact events Under 100m: Sucks if it lands on you. Similar to an H-bomb. 100 - 500m: Local devastation, potential for tidal waves, light climate impacts. Similar to Krakatoa. 500m - 1km: Regional devastation, climate impacts, potential end of civilization. 5km: Complete destruction of everything within thousands of km, worldwide ecological and climate destabilization, definite end of civilization. 10km: Dinosaur Killer. We know of one object that is dangerous in the 1km size range: (29075) 1950 DA, which could hit the earth in 2880. Everything else is either zero hit probability to the limits of our prediction ability, tiny, or undiscovered. And if it's bigger than 100m and a NEO, it's probably been found and plotted. Most of the moderately big asteroids, which might be potentially dangerous, that we're discovering now are things that loop eccentrically between the inner planets and the main belt. That means they spend the majority of their time well away from us.
|
| # ? Feb 14, 2013 16:07 |
|
|
dee eight posted:Surf's up, dude! Kowabunga! There's a fiction book called Lucifer's Hammer (Larry Niven?) that's a decent read about a comet smacking into the earth. One scene describes some hodads riding a totally gnarly wave (like 400 feet high) caused by ocean impact. You know, if a comet hits the Earth we're all hosed anyway, so I'd be all about surfing the tidal wave of doom. Might as well have some fun with the apocalypse! Cannot Find Server fucked around with this message at Feb 14, 2013 around 21:23 |
| # ? Feb 14, 2013 21:08 |
|
|
dee eight posted:Surf's up, dude! Kowabunga! There's a fiction book called Lucifer's Hammer (Larry Niven?) that's a decent read about a comet smacking into the earth. One scene describes some hodads riding a totally gnarly wave (like 400 feet high) caused by ocean impact. I am no poo poo currently re-reading this book (I love me some end of the world fiction). Only one of the surfer dudes manages to stay up, and he face-plants into a high rise..
|
| # ? Feb 14, 2013 21:22 |
|
|
|
| # ? May 19, 2013 11:17 |
|
|
Devyl posted:Here is Bill Nye explaining what would happen if it hits.
|
| # ? Feb 15, 2013 01:18 |
|
