Sorry, ladies and gents, but my fingers are now ground down into nubs and I need to stop. Thank you for your questions!

I am Dr. Marc Fries, a senior scientist at the Planetary Science Institute in Tucson, Arizona, and a visiting scientist at the Smithsonian Institution. I study meteorites and early Solar System formation and am here to answer any questions you may have about the meteor over Russia, the "near miss" by asteroid 2012 DA14, or any other questions you may have about meteors and meteorites.

Comments: 565 • Responses: 65  • Date: 

CHarleq135 karma

Wow, your job rocks!

Blitchy_Blitch135 karma

He shouldn't take his job for granite.

DrMarcFries159 karma


DrMarcFries45 karma

Yes it does! And you can do it too if you work at it. It is a wonderful thing to have a job that you love.

NvaderGir82 karma

What's your favorite meteor/meteorite occurrence in history that you find fascinating?

DrMarcFries314 karma

Ever heard of Antoine de Saint-Exupery, the man who wrote The Little Prince? In the '20s and '30s he was a French Aeropostale (air mail) pilot, flying wood-and-fabric airplanes to deliver the mail to far-flung corners of the world. He was once forced down on a small, high plateau in Africa by mechanical troubles. Stranded, he walked around the plateau. He noticed that the plateau was too tall to ever have been visited before, and that it was composed entirely of light-colored rocks. There in the moonlight, he found an odd, dark rock that had no place there. Saint-Exupery identified the rock as a meteorite, as the only way it arrived was from the canvas of stars above, "just as a blanket spread under an apple tree receives only apples". He went on to find three meteorites there in the darkness, and to identify them as such back in the 30's was quite the intellectual accomplishment.

DrMarcFries70 karma

Greetings! I am online and happy to take your questions at this point.

DrMarcFries75 karma

I just received an email from a prominent meteor expert who estimates the energy output of this bolide at greater than 100 ktons of TNT, which makes it the most powerful meteor since the Tunguska event in 1908! His estimates also state that the pre-atmospheric size of the meteoroid was roughly 15m in diameter. Compare that to 2012 DA14 passing by the Earth later today, which is twice that diameter! Now imagine what would happen if THAT one were to strike us...

Reddballs62 karma

Where the Mayans off by 2 months or what?

DrMarcFries94 karma

Heheheh Meteors like today's must have occurred during Mayan times as well. You have to wonder what they must have thought about such events.

cableshaft58 karma

  1. About how often do meteors of about the same size as the one from today enter our atmosphere?

  2. If Superman was out there patrolling the skies this morning, would he have been able to spot the incoming meteor in time to do something about it?

DrMarcFries84 karma

Meteoroids (that is, a body smaller than as asteroid) of this size strike the Earth's atmosphere about once a decade or so. As for Superman, it would depend on how closely he was paying attention! I suspect that he would be watching out for us if he saw it coming.

SuperNixon49 karma

How big of a bomb would Bruce Willis have needed to blow up that metor?

DrMarcFries66 karma

Hm. That's a tough one. Scientists are divided as to the best course to take to eliminate dangerous asteroids, and blowing them up may not be the best action. If we were to blow one up, however, I would approximate that your average non-thermonuclear warhead (tens of kilotons TNT yield) would be enough to completely disrupt the body from today's event. Bear in mind that that is a VERY rough guess, though!

Shuawuzheer48 karma

What is your favorite mind boggling scientific fact?

DrMarcFries338 karma

Stretch your arms all the way out, and let's imagine that the distance from one fingertip, across your body, and out to the other fingertip represents 4.5 billion years. That's the age of most meteorites. Now, take a nail file and make a single swipe across the fingernail on your middle finger. If the distance across your outstretched arms is 4.5 billion years, then with that nail file swipe you just erased ALL of recorded human history. But your average meteorite has been around for the entire outstretched-arms distance - for 4.5 billion years!

Braindog44 karma

This is truly your day to shine!

How big must a meteorite be to destroy say, an average house?

DrMarcFries68 karma

Thank you! I like to see it as a great day for the average person to come in contact with planetary science. It's a wonderful research field.

To destroy a house, a meteoroid would have to be even bigger than the event today in Russia. It would have to be large enough to reach the ground without slowing down to an aerodynamically-limited speed, and to strike the ground and cause a crater. With that said, falling meteorites can still cause damage. Look up the Lorton, VA meteorite fall from a few years back - a ~fist-sized meteorite plunged through the roof of a doctor's office, which was luckily unoccupied at the time.

ilrasso36 karma

Wiki said meteorites are most likely to impact at 45 degrees. Why is that?

DrMarcFries56 karma

Beats me. Very few to none are going to strike perpendicular to the atmosphere, so I doubt the average is 45 degrees. Sounds like a mistake to me.

laxbro_36 karma

How do scientists go about tracking meteors? How do some meteors pass through undetected? (Like the one in Russia).

DrMarcFries58 karma

Meteoroids and asteroids are tracked using optical telescopes and sometimes by radar, although scanning the entire sky with a radar wouldn't work to detect everything out there - the sky is just too big. Some meteoroids get by because they're too small and/or dark to be seen by optical telescopes.

PenguinHero12 karma

Too dark? Could you expand on that please? And does the 'and/or' mean that we could have a massive but dark one which would still get past our monitoring?

300saders9314 karma

The 'darkness' of a rock out in space is called its albedo, which tells you how much light it reflects. It if has a really low albedo, it means the surface material doesn't reflect much of the sun's light, so it's difficult to see out in space. I'm assuming that's what DrMarcFries is referring to.

DrMarcFries3 karma


DrMarcFries3 karma

Yes, too dark as in, the surface is nonreflective and black. Like coal! Many asteroids contain a significant amount of carbon, and so they can be very dark to look at. Trying to find these ones against the black night sky is a challenge. So with the and/or, I was trying to say that some are too small to spot until they get very close to us, and others are too dark to pick out against the night sky. And then some are both dark and small.

Blitchy_Blitch33 karma

How common is it for meteorites to contain radioactive or otherwise harmful material?

DrMarcFries87 karma

Asteroids, meteoroids, and meteorites (rocks that actually reach the ground) are NOT radioactive. On Earth, rocks usually are radioactive if they are part of a radioactive element's ore. That requires the movement of a lot of hot water in the Earth's crust, and that process does not happen on asteroids. Meteorites are safe to handle.

thetoughtruth30 karma

What is the largest misconception the public has about meteors, meteorites, or asteroids?

DrMarcFries51 karma

Hm. Pick your favorite - that they're radioactive, flaming hot, show up unannounced on your lawn overnight, or bring hazardous bacteria to our planet. None of these things are true.

Shinob126 karma

But are used to make magical swords right?

DrMarcFries11 karma

heheh There actually are daggers made out of meteorite metal, to include at least one in the Smithsonian's collection. To the best of my knowledge they don't glow when orcs are near, however.

lets_dance28 karma

Thank you so much for doing this! I keep hearing rumblings about the meteor that is going to passing over today closer than some of our satellites, but I haven't read anything recently about when it may be passing back around potentially even closer. Do we have anything to worry about?

DrMarcFries55 karma

You're welcome! And no, we have nothing to worry about. The asteroid 2012 DA14 will pass very close to the Earth today, but scientists have been watching it for many months now and are confident that it will miss our planet. On the other hand, we get a close look at this interesting asteroid without having to pay for a space mission!

kadf27 karma

-Did we have any advance notice that the asteroid/meteor that hit Russia was coming? -I also heard that the one flying by is worth $195 billion, is the one that hit Russia (or whats left of it) worth anything near that amount you think?

DrMarcFries45 karma

No we did not. This meteoroid, for as much damage as it did on the ground, was too small and/or too dark to be seen before it hit the atmosphere.

Diraka26 karma

So... do the exhibits come to life at night?

DrMarcFries65 karma

Only when I'm not watching, apparently.

FireAirWaterEarth24 karma

What dangers does a meteor of this size pose? Is this a rare event?

DrMarcFries50 karma

This event has done all the damage its going to do. It was too small to reach the ground without breaking up in the atmosphere, so it didn't create an explosion crater on the ground like that seen in Meteor Crater, Arizona. The damage in this event was caused by what is basically a powerful sonic boom, as the very fast meteoroid struck the Earth's atmosphere like a rifle bullet fired into a swimming pool.

DrMarcFries46 karma

As for rarity, an event this size will occur about once a decade. Smaller meteorite falls happen all the time, though - there is approximately one meteorite fall on Earth every day. Most meteorites fall in the ocean or simply go unnoticed, however.

thirdrail6923 karma

Any word yet on what type it is?

DrMarcFries64 karma

I've seen pictures of a hole in an icy lake that seems to have been caused by a falling meteorite. The description in that article says there are small, dark stones 0.5 to 1 cm in size among the icy debris. That hints to me that this was a chondrite - a type of meteorite composed of stone and small bits of metal. We won't know exactly what kind until the fragments are examined by an expert.

-Hephaestion-20 karma

Suppose that we have spotted a meteorite, that will inevitably collide with Earth in, let's say, a decade. It has a very high density so it's hard to destroy, it has a diametre of about 7 miles. In what way would it be possible to prevent the extinction of mankind?

DrMarcFries58 karma

The best option, if we had all options available, would be to have thriving human civilizations on multiple planets and moons. That way, even if some doom-rock of an asteroid were to cause a mass extinction, humanity would carry on. Bear in mind that this HAS happened on Earth before - notice that there aren't any dinosaurs roaming your neighborhood at the moment (other than birds, but that's another story).

Troomaan16 karma

How often do people come to you with chunks of things like hematite or other oddly shaped mineral deposits and ask you if they are from space?

DrMarcFries37 karma

All the time! I enjoy it, actually. Most rocks that people bring to me are not meteorites, but I'm happy to show them what a real meteorite looks like and offer advice on how to find them.

ndnOUTLAW14 karma

What is the smallest meteorite we are able to detect from space? What technology exists to stop meteors?

DrMarcFries29 karma

The smallest meteoroid? (A meteoroid is a small rock flying through space, and a meteorite is one that reaches the Earth's surface) I'm afraid I don't know exactly, but it will be about the size of the parent asteroid of Almahatta Sitta (AS). AS is a meteorite recovered from Sudan that was detected in space before it fell to Earth, so we knew when and where it was going to fall. It managed to get pretty close to Earth before it was seen, so that's probably the lower size limit for detection.

As for stopping them? We currently have NO defense against asteroids. If one were spotted on a collision course with Earth, we could make preparations on the ground but there is no real plan in place right now for dealing with it before it strikes our planet. My humble suggestion is to fix that little discrepancy...

AguyWITHstuff13 karma


DrMarcFries26 karma

The chances of physically destroying the Earth are vanishingly small. About 4 billion years ago, the Earth was struck by an approximately Mars-sized body and the resulting collision produced our Moon. Even then the Earth survived, and today there are no large bodies in irregular orbits that could reproduce that event. But if you mean an asteroid large enough to cause extinctions, the chances are very small. ...but not zero. Bear in mind this exact thing happened 65 million years ago with the Chixulub impact which played a major role in wiping out the dinosaurs.

robin112511 karma

  1. How did you become an expert in meteors and meteorites?

  2. When did you first become interested in the field?

DrMarcFries25 karma

I still have a lot to learn, and I'll be working to correct that until I'm too feeble to pick up a book. But I was first interested very late into getting a Ph.D. in materials science. A friend of mine brought a funny rock into the laboratory and asked me to collect some spectra on it. He told me it was a meteorite and I tried to kick him out of the lab because I thought he was pulling my leg - only museums have meteorites, after all! Turns out I was wrong on both counts. It WAS a meteorite called Portales Valley, and meteorites are actually very easy to come by, and are wonderful in the sense that they are ancient relicts of the formation of our Solar System that you can actually hold in your hand. I examined the meteorite for him and was spellbound by this incredible rock, which was unlike anything I'd ever seen. I was hooked, and have been studying them ever since.

ProfessorMack11 karma

How would you compare the asteroid that hit Russia and the one that's going to miss the earth by about 15,000 miles?

DrMarcFries21 karma

We saw one coming, and missed the other entirely! :-)

Seriously, we'll know more about both when we A) get pieces of the Russian meteorite into a laboratory, and B) get a good look at the near-miss asteroid later today.

rob100510 karma

Where can one keep updated on such things? Normally this sort of thing is all over the internet/news for a day or 2 then seems to disappear! I find it fascinating too, and would love to know more about it after testing. Very jealous of your job, keep up the good work!

DrMarcFries16 karma

For meteors in the United States, I suggest the American Meteor Society's web page:

There are websites for the various astronomy organizations who are watching for Earth-crossing asteroids as well, but I'm afraid I don't know them off-hand. A web search will get you there, though. Search for "near Earth objects" or something along those lines.

guy-le-doosh9 karma

Are you trackin, gang?

DrMarcFries22 karma

Papa Whiskey, what's your position?

Tess479 karma

Is the Russia meteor the same one the news said was going to pass between the moon and earth? or something completely different?

DrMarcFries14 karma

We don't know yet. The best way to find out will be to compare the trajectories of the two bodies and see if they are similar. At this point, we don't know enough about the trajectory of the Russian bolide. (A bolide is a very bright meteor that includes a detonation event)

adamjf098 karma

Why do meteors explode? Aren't they just large pieces of space rock that is heated up when entering the atmosphere?

DrMarcFries32 karma

They explode because they strike the atmosphere at very high velocity. Meteoroids are moving between ~10 and 80, even 100 km/s when they hit the top of the Earth's atmosphere. At those speeds, meeting the atmosphere is a pretty brutal event. It's like doing a belly flop into a swimming pool - sure, the water is nice and liquid and squishy, but if you hit it hard and slow down quickly, it's gonna hurt! In a meteoroid's case, that belly flop into the atmosphere occurs at speeds high enough to turn solid rock into a superheated gas, and quickly enough to slow down from 10s of kilometers per second to tens of meters per second, all in only a few seconds' worth of blazing fireball.

ShiftyPons8 karma

What sized near-Earth asteroids/meteoroids is it currently possible to track with the systems nowadays in place? It seems this Chelyabinsk event caught everyone by surprise and wasn't on anyone's proverbial or literal radar...

DrMarcFries10 karma

The best tool in use is the optical telescope. We have radars, but there's simply too much space out there to effectively scan it all, given current equipment and funding. Many amateur astronomers contribute to this effort.

rageously7 karma

How does the angle at which a meteor strikes the earth affect its destructive force? For example, had this meteor entered our atmosphere at a shallower angle could it have exploded with more force like the one over Siberia a century ago? Or if it had come straight in, would it have struck harder, therefore resulting in a bigger blast on the ground?

DrMarcFries13 karma

Ah, physics! We love physics. The infall angle is one of the factors in destructive force. An asteroid plunging straight into the atmosphere MIGHT have a better chance of reaching the ground than one that enters at a glancing angle, but it depends strongly on the velocity, mass, and mechanical strength of the asteroid. The meteoroid that struck today would not have reached the ground in any event; it was too small.

With that said, some of the PIECES of today's Russian event probably reached the ground, but only as free-falling rocks and not screamingly-fast cosmic bullets.

SkiesAreGrey6 karma

What about this particular meteroite was so different when it made the news? If they happen every ten years or so, why is it such a huge ordeal? The media plays it up to seem as if this is a once in a lifetime thing. But I don't recall anything ten or so years ago about a meteorite like this.

(Also, unrelated, but I'm starting an internship with the Smithsonian in a couple weeks, what are some fun things to do in the DC area?)

DrMarcFries12 karma

In a word, it was BIG. That, and people got hurt. Take your average everyday event and find a version of it where people have to visit the hospital, and you've probably got a news item. And there have been several very large events like this over the past few decades. Another very large one was several years ago over Indonesia (and mostly over water). It didn't make YouTube, so it was overlooked. There was another one over India/Pakistan a while back during a particularly tense period in their relationship, but that was over a rather remote area if I recall correctly.

As for DC - go ride the Metro and watch the people. It is a train ride, an underground excursion, and a circus all in one.

ReadDinger6 karma

It was reported that the meteorite today exploded while it was still in the air. Why did it not crash into earth as one, flaming ball? If I heard right it created a sonic boom when it exploded.

DrMarcFries17 karma

It lost the battle between mass and air pressure. The air pressure it experienced upon striking the atmosphere started breaking it up, and it wasn't massive enough to shrug off the damage and plunge into the ground. So it broke up between ~50 and ~20 km above the ground. If it were larger, it might have survived the trip to the ground and formed an explosion crater. As it is, the damage it could cause was pre-programmed into it by its size.

Socially_Awkwardx25 karma

Is global warming responsible for the Russian meteor incident?

DrMarcFries20 karma

Nope. The two are completely unrelated.

aDeadChipmunk4 karma

Does the phrase "meteoric rise" when used to describe someone who has obtained some sort of fame frost your cookies? [it does mine.] They actually fall from the sky burning in flames if I remember correctly.

DrMarcFries7 karma

I'm convinced that the English language was invented pretty much to befuddle anyone who didn't grow up with it. But then, I suppose one could have a "meteoric FALL", too, which is a pretty dramatic descriptor.

Tizoptera4 karma

Did the whole meteor break up into smaller pieces during entry? Or was there a larger piece that impacted?

DrMarcFries9 karma

Most of the meteoroid was destroyed - the bright part of the fireball was basically the process of turning stone into gas. But some of it - a small fraction of the original mass - almost certainly survived to reach the ground as meteorites.

cant_help_myself3 karma

How is the search conducted to find the bits that fell to earth (falls)?

Follow-up: If I find one, do I get to keep/sell it or am I supposed to turn it in somewhere?

DrMarcFries8 karma

The science/art of finding meteorites includes assembling eyewitness accounts, some trigonometry-heavy analysis of videos and pictures to re-create the path of the body, and some physics-based calculations of the expected flight paths of falling meteorites. Or, you get lucky and someone saw where they landed! As for keeping them, that depends on the law of the land where you found the thing. Some US agencies like the BLM are forward-thinking enough to have policies in place on what you can keep for yourself. Some countries, by contrast, have very restrictive policies and as a result the meteorites in those countries tend to rot into the ground, lost to science forever.

bringabook3 karma

I'm a geology major and I want to go into planetary geology. Do you have any suggestions or tips for me?

DrMarcFries6 karma

Talk to lots of people. LOTS of people - professors, other students, scientists, grad students. More than you think you need to. Ask anything and everything you can think of - they'll either help you, or you didn't really want their advice anyways because they suck. Research the schools that do the sorts of things that interest you, and talk to people there. Form a plan, but be willing to change it as you go. Try lots to things in order to figure out what you love to do, and then do that.

BrahmenNoodles3 karma


DrMarcFries11 karma

Oh boy... I'd love to answer all of these but there are a lot of unanswered questions I'd like to get to. Let's see... I've answered the first one already, so I'll answer the second one here. There are no "new" elements in meteorites, in the sense that there's nothing in there that we haven't seen on Earth already. That makes sense, because fundamentally the Earth and asteroids were all originally assembled from the same cloud of dust that gas that swirled around our Sun some 4.5+ billion years ago. There are a few unusual new minerals in meteorites, however, and that's a consequence of their formation under chemical conditions that are unlikely on Earth. They were then protected from wind and rain by ...well, the fact that there are neither wind nor rain on asteroids! Kinda convenient, that.

kirstencarlson3 karma

curious if the video coming in from so many different sources can help you with data analysis--like angle of descent, speed, other variables that might be quantitative in nature or if it's helpful 'qualitatively' speaking.

DrMarcFries4 karma

Yes! Basically, once you measure the angles in the pictures and videos and locate the spot where the pics were taken, it is a matter of trigonometry. You re-assemble the 3D path of the meteor from the various images. From there, you will get an idea of where any meteorites landed. Yay, science!

meepbob3 karma

Why do these objects "explode" at a certain altitude, rather than slowly burning up little by little to nothing?

DrMarcFries6 karma

It lost the battle between mass and air pressure. The air pressure it experienced upon striking the atmosphere started breaking it up, and it wasn't massive enough to shrug off the damage and plunge into the ground. So it broke up between ~50 and ~20 km above the ground. If it were larger, it might have survived the trip to the ground and formed an explosion crater. As it is, the damage it could cause was pre-programmed into it by its size. (sorry for the cut and paste...!)

ecbremner2 karma

How different do meteorites tend to be in composition from one to another?

DrMarcFries5 karma

Great question! There are iron meteorites, which are formed when molten iron-nickel coalesced into the infernal core of a larger body, then that body was broken up to scatter its iron heart through the cosmos. (I've been writing for a few hours now and I'm waxing poetic!) Then there are "stony" meteorites composed mostly of silicates, either from small bodies that never got hot enough to form a liquid, metallic core, or from the metal-depleted surfaces of those bodies. Then there's the carbonaceous meteorites, which contain - you guessed it - a large amount of carbonaceous material. That's the simple version. There are dozens of types of meteorites, from asteroids, comets (maybe) and even other planets. There are some whose origins are still mysteries, as well.

theduke99992 karma

Whats the biggest metorite ever found? And if we were knocked ojt of orbit, would Earth be considered a meteor or a rogue planet?

DrMarcFries10 karma

Hoba!! Beware when speaking of Hoba, for we speak of her only in hushed tones of reverence. Ahhhh, Hoba... Many, many tons of alien goodness...

The Earth is way to big to knock it out of orbit, luckily. It was once clobbered by a body large enough to create the Moon out of the resulting spray of rubble, and here we still are. Individuals can still go rogue if they choose to, but the entire planet ain't going to.

rachelitis2 karma


DrMarcFries9 karma

The most interesting thing is basically that our Solar System is composed of many bodies, all orbiting the Sun and still running into each other even today. Before a few prominent meteorite falls a few centuries ago, this fact that we take for granted today was not commonly accepted. In ancient times, meteorites were explained as rocks ejected by distant volcanoes or ejected from caves! I'm glad we got that straightened out.

mybreathyourlung2 karma

Greetings from across the mall!

DrMarcFries3 karma

Howdy! How's the weather over there?

Mikeydoes2 karma

How long until we start collecting raw materials from space?

DrMarcFries7 karma

The planet already is, in a sense. Some 40,000 tons (give or take) of meteorites fall to Earth every year. As for mining asteroids and such, that is a VERY difficult endeavor and I'm skeptical that it will be practical any time soon. But we should start NOW, or we never will.

thompa17172 karma

What made you interested in meteors/ meteorites?

DrMarcFries3 karma

Had a buddy bring one into the lab one day, when I was finishing up my degree (of course! bad timing). After I stopped trying to throw him out of the lab because I thought he was pulling my leg, I was fascinated by the Portales Valley meteorite he had and was hooked on meteorite research. I then served as a post-doctoral student at the Carnegie Institution of Washington. The Carnegie is a wonderfully permissive laboratory where research is involved, allowing and encouraging the scientists to follow their interests. I was able to start studying meteorites in earnest, and have been doing it ever since.

Big_Don_2 karma

Hi, thanks for doing an AMA. One question: How big do you think the meteorite that just hit Russia was before it hit our atmosphere?

DrMarcFries4 karma

My pleasure! I've heard numbers from 10 to 50 tons pre-atmosphere, but we don't have enough info in hand to really tell yet. My estimate lies towards the top end of that range, but we need to know what kind of meteorite it is and how much power the fireball generated.

[deleted]2 karma

Another scientist said the shock wave was directed downward due to its shallow trajectory. How would a shock wave behave on a steep angle meteor and why the difference?

DrMarcFries5 karma

Shock waves radiate outwards in all directions from a fast-moving object, so I'm not sure I fully understand the point the scientist was making. Perhaps he/she was saying that the shock wave follows the ground track of the meteor, and so it would propagate over a longer "footprint" on the ground than if it plunged steeply into the atmosphere...? I can't guess what the scientist was trying to say, but at least the above is a true statement.

blunted2 karma

Whats your favourite meteorite? For example I'm an amateur collector and I have a soft spot for Allende , I have a small slice and its just fascinating in terms of its age and composition.

DrMarcFries4 karma

My favorite meteorite is the one I most recently handled. I'm simple. :-)

MicroCosmicMorganism2 karma

How likely is it that we shall see an "Extinction event" causing meteorite in our lifetime?

DrMarcFries4 karma

Very unlikely. The last one to occur was 65 million years ago with the Chixulub impact and the end of the dinosaurs. Of course, the flip side of that is that we KNOW that these things do happen... (insert ominous disaster-flick music here)

DonChrisote2 karma

I've heard that the event in Russia has nothing to do with the huge meteor that's passing by us... how can that be true? It seems like a big coincidence. Thanks!

DrMarcFries3 karma

<snip from above> Dunno (if they're related) yet, and I wish I knew! We will be able to answer that question when we know the trajectory of the Russian object, and can compare it against the trajectory of the near-miss asteroid. I understand that Phil Plait of Bad Astronomy was hinting that the two events are unrelated, and so was the NASA Space Environment Office. But I retain a healthy degree of uncertainty at this point. :-) <snip>

MegAtWork2 karma

If there was a huge meteorite hurtling towards earth that would cause significant damage to society or completely wipe out civilization, would astronomers tell us ahead of time?

DrMarcFries5 karma

Would the astronomers? Oh you bet they would. That's the whole reason they are looking!

username_confusion1 karma

Is it possible for asteroids to contain new and undiscovered elements? If so, has it ever happened before?

DrMarcFries5 karma

Nope. We've already fleshed out the periodic table with all the elements which are stable, and even with a few that aren't. Some mineral phases have been found in meteorites that haven't been found on Earth, but they are very rare minerals in the grand scheme of things.

rarahertz1 karma

If a large meteor impact was immenent, could we actually do anything about it? Would we blow it to tiny pieces, or somehow split it into 2 large pieces whose trajectory would miss the earth.

If a dinosaur-extincting size meteor was on the way, could the government somehow keep it secret and only the privileged get into the shelters? Or is it easy enough to spot these meteors such that your local university would see it and spill the beans?


DrMarcFries6 karma

There are a variety of plans floated about for dealing with dangerous asteroids... Blowing them to fragments is certainly an option, although there's some discussion as to just how possible and/or preferable that option is. (As a former Marine myself, I REALLY like the idea! hehe) Other plans include painting one or more sides of it and letting sunlight push it away from us. That sounds insane, but it really is an option - physics gives it a thumbs-up. There's also the option of putting some sort of engine on the thing and thrusting it away from us. The thing is, NONE of these options are currently available. All current nuclear-tipped missiles on Earth are designed to go from one spot on the planet directly to another, and don't even make it to Earth orbit much less a distant asteroid. The only plan we currently have available is to make disaster-preparation plans on Earth. As for keeping it quiet, personally I think the notion of conspiracy is to antithetical to human nature to work well. People love to blab. But that's a discussion for another venue.

joshorson1 karma

About how many joules of energy does a meteorite coming into the Earth's atmosphere produce?

DrMarcFries3 karma

Depends on the mass and velocity of the meteoroid. The vast majority of meteors are caused by tiny (sand-grain sized), fast-moving (30+ km/s) little fragments, and many of those aren't even powerful enough to be seen with the naked eye.

Carcul1 karma

Is the Russian metiorite related to the near-miss one tonight? If so, should we expect more, and where? Are we more likely to spot them now with knowledge gained last night?

DrMarcFries4 karma

For the first, <snip> Dunno yet, and I wish I knew! We will be able to answer that question when we know the trajectory of the Russian object, and can compare it against the trajectory of the near-miss asteroid. I understand that Phil Plait of Bad Astronomy was hinting that the two events are unrelated, and so was the NASA Space Environment Office. But I retain a healthy degree of uncertainty at this point. :-) <snip>

And as for being better prepared to find more of them in the future, it certainly can't hurt. The biggest roadblock to science is usually funding. They say that "dreams without funding are fantasies", and that's especially true of science. Not that I'm glad to see people hurt in Russia, mind you, but all things considered (ahem, dinosaur extinction...!) this event was a light little love-tap from the cosmos that will hopefully draw attention to the need for more effort in asteroid detection/deflection.

ihadanicknameonce1 karma

Did Russia have any warning it was coming at them? The vide I saw (here on reddit) made it seem as though they were not aware.

DrMarcFries6 karma

Nope! It came out of a clear blue sky. So to speak.

sandburn0 karma

In your earlier Q&A, you state that

The fireball is caused by friction with the atmosphere and most of the meteorid is vaporized before it hits the ground.

However, I have come to understand that it is Ram Pressure (and even possibly Impact Ionization?), not friction that cause the heat (and resulting fireball).

Could you elaborate?

DrMarcFries3 karma

The key words there are "ram" and "impact", both descriptors of items colliding with each other. By "friction", I'm balling these things up under a single term to describe the collision of air molecules with the meteoroid.

A-Lav-1 karma

Why do they always fall in Russia?

DrMarcFries2 karma

GREAT QUESTION. They have some sort of national meteorite greed over there! Seriously, there were four meteorite falls in the US last year. Two in California, one in Nevada, and one in Alabama. Meteorites were recovered from all of these events.

themichelinman-1 karma

When will the world end?

DrMarcFries4 karma

Probably the day when I finally decide that I've got my act together. Or, given my luck, the day BEFORE that day.