Calling all scientists and science buffs (:

DrunkenLilacs · Aug 17, 2011

Okay, so, I have this WIP that has a scientific element. Basically, an asteroid that was thought to have passed by has circled the earth and now has come back around, threatening to hit it. Is that plausible? Can an asteroid do that?

Also, let's say the asteroid is the size of London. How big would the damage be? I wa thinking of having it destroy one part of the U.S.--the west-- its surrounding areas and possibly states--once the impact happens, everyone around those areas die, but there's still a good amount of the country that's still in tact, for now at least.

I've read a lot into the aftermath--fireballs, radiation, a lot of wind, ejecta--but I want to know if the impact of an asteroid that big would just kill everyone in a short amount of time, if there was no use of evacuation, if let's say, there's not exactly a safe zone to evacuate to.

Am I making sense? I feel like I'm rambling. I just want to know if one: it's plausible for an asteroid to orbit around the earth, come back and threaten to hit (and if scientists would catch it early on and do some thing about it); and two, what the impact would be like.

It's just a small portion of my WIP--I'm not going to go into detail about the asteroid in the story, but I think it would be nice if I knew it was plausible.

Help? Please and thank you?

mirandashell · Aug 17, 2011

ERmmm.... I'm no expert but I'm fairly sure that an asteriod would not loop back around and hit the Earth. Due to the laws of motion.

And we would know fairly early about its trajectory. So we would know it was going to hit.

BunnyMaz · Aug 17, 2011

Normally, asteroids are either rogue or they orbit the Sun. A rogue asteroid passed straight past and there would be no conceivable reason for it to turn around. Orbiting asteroids may well come back and threaten to hit us... next orbit. Which may be a very long time, depending on the orbit itself.

You could perhaps wrangle some science by having a VERY FLUKEY event where the asteroid's path leads it to slingshot around another planet further out. But orbiting Earth? No. Look at it like this...

Everything in space moves in sensible, measurable, calculable arcs effected by the gravitational pull of the bodies around it, so you would need to find some way to make it work.

As to the damage... the meteor 1997xf11 is approximately 2.8km in diameter, nowhere near the size of London, but if it were to hit Earth...

From here...

In 2028, the asteroid 1997XF11 will come extremely close to Earth but will miss the planet. If something were to change and it did hit Earth, what you would have is a mile-wide asteroid striking the planet's surface at about 30,000 mph. An asteroid that big traveling at that speed has the energy roughly equal to a 1 million megaton bomb. It's very likely that an asteroid like this would wipe out most of the life on the planet.

It's difficult to imagine 1 million megatons, so let's try some smaller sizes. Let's say that an asteroid the size of a house crashed on Earth at 30,000 mph. It would have an amount of energy roughly equal to the bomb that fell on Hiroshima -- perhaps 20 kilotons. An asteroid like this would flatten reinforced concrete buildings up to half a mile from ground zero, and flatten wooden structures perhaps a mile and a half from ground zero. It would, in other words, do extensive damage to any city.

If the asteroid is as big as a 20-story building (200 feet on a side), it has an amount of energy equal to the largest nuclear bombs made today -- on the order of 25 to 50 megatons. An asteroid like this would flatten reinforced concrete buildings five miles from ground zero. It would completely destroy most major cities in the United States.
By the time you get up to a mile-wide asteroid, you are working in the 1 million megaton range. This asteroid has the energy that's 10 million times greater than the bomb that fell on Hiroshima. It's able to flatten everything for 100 to 200 miles out from ground zero. In other words, if a mile-wide asteroid were to directly hit New York City, the force of the impact probably would completely flatten every single thing from Washington D.C. to Boston, and would cause extensive damage perhaps 1,000 miles out -- that's as far away as Chicago. The amount of dust and debris thrown up into the atmosphere would block out the sun and cause most living things on the planet to perish. If an asteroid that big were to land in the ocean, it would cause massive tidal waves hundreds of feet high that would completely scrub the coastlines in the vicinity.

In other words, if an asteroid strikes Earth, it will be a really, really bad day no matter how big it is. If the asteroid is a mile in diameter, it's likely to wipe out life on the planet. Let's hope that doesn't happen anytime soon!

London is approx 25 miles wide, so you maaaay want to think smaller.

Keep in mind also, that most of the damage to life from impacts of any size isn't the actual impact, but the resultant earthquakes, volcanic eruptions, tsunami and choking dust clouds that result. Anything that has a large enough physical impact crater to knock out a sizeable chunk of the USA would wipe out everything and, at the very least, give us possibly a new moon. We're talking ocean and atmosphere boiling impacts, at that point.

PrincessofPersia · Aug 17, 2011

An example: there is an object coming towards Earth as we speak. It is called YU55, and it will pass so close to us that it will come within the Moon's orbit, blowing by us at an altitude of only 201,700 miles. It was discovered in 2005. So there is usually plenty of warning. The next large object to approach us won't be until 2028 (which the previous poster mentioned). It won't fly by, then circle around and come back to hit us. The Earth's gravity isn't strong enough to do that.

YU55 is only 1/4 a mile across (about 400 metres or 437 yards), yet if it were to strike the Earth, it would exert a force equivalent to 65,000 atomic bombs, leaving a crater six miles wide and 2,000 feet deep. London is what, 35 miles in diameter (if you stay within the M25)? There would be no point in evacuation for an asteroid that size, as all life on this planet would be gone.

Mutive · Aug 17, 2011

One more thing to consider is where the meteor hits. It's going to do different types of damage from landing on the ground than in the ocean. (Note that the ocean is most likely, just due to where most of the surface area of the planet is.)

An ocean one, interestingly enough, is likely to be significantly worse than one that lands on land. Either way, though, like Bunny says - a big one can easily eradicate all life on earth. FUN! ^_^

DrunkenLilacs · Aug 17, 2011

Thanks for the quick and information responses guys! I understand now. It's very not likely, so I think I might just have it on one course to hit earth, you know, without u-turning or anything. It's more plausible that way, I think. So assuming that because we know about YU55 and 1997XF11, we'll probably know if there was a foreign body setting out to hit us. Do you think we could do anything about it, if that's the case? Like alter its path or destroy it somehow? Or build shelters on earth to save ourselves?

I'm going to take the advice to make the asteroid smaller. I seriously didn't think it would have that much power--it's crazy scary. Thanks again for the help, guys! Science was never my strongest subject hahaha.

PrincessofPersia · Aug 17, 2011

DrunkenLilacs said:
So assuming that because we know about YU55 and 1997XF11, we'll probably know if there was a foreign body setting out to hit us. Do you think we could do anything about it, if that's the case? Like alter its path or destroy it somehow? Or build shelters on earth to save ourselves?

It's a safe bet that we'd know about it in advance. Because we'd know about it way in advance, it wouldn't take much to make sure we didn't get hit. All we'd have to do is alter its orbit by a small amount, and we'd be safe. A small push from rockets or from an object sent near the asteroid could do the trick, which is what NASA and other scientists are suggesting we'd probably do. And if it doesn't work the first time, we'd have plenty of time to try again. It is VERY unlikely (read: virtually impossible) that we'd have an Armageddon type scenario where we only have three weeks to do something.

DrunkenLilacs · Aug 17, 2011

PrincessofPersia said:
It's a safe bet that we'd know about it in advance. Because we'd know about it way in advance, it wouldn't take much to make sure we didn't get hit. All we'd have to do is alter its orbit by a small amount, and we'd be safe. A small push from rockets or from an object sent near the asteroid could do the trick, which is what NASA and other scientists are suggesting we'd probably do. And if it doesn't work the first time, we'd have plenty of time to try again. It is VERY unlikely (read: virtually impossible) that we'd have an Armageddon type scenario where we only have three weeks to do something.

Yeah, that's what I was thinking, too. And we probably have the technology to alter its course. *sigh* Armageddon was a terrible movie...what they did to stop the asteroid was implausible, also.

Has anyone seen the movie Melancholia? I thought it had various holes in plausibility...it's about a planet called Melancholia that was hiding behind the sun, and is threatening to crash into earth. Could that happen? Another Earth was also another movie that defied the rules of science--in the movie, another earth-like planet was visible through our atmosphere...now, that's more fiction-bending.I suppose that can't really happen.

Here are the trailers, if anyone's interested:
Another Earth: http://www.youtube.com/watch?v=N8hEwMMDtFY
Melancholia: http://www.youtube.com/watch?v=wzD0U841LRM

But thanks, PrincessofPersia!

Drachen Jager · Aug 17, 2011

A couple of impact simulators.

http://impact.ese.ic.ac.uk/ImpactEffects/

http://www.armageddononline.org/asteroid-impact-simulator.html

Yes it is possible for an asteroid to loop around that way, though the boffins at NASA, ESA and the Russian space program track them and have a pretty good idea where they'll end up.

http://neo.jpl.nasa.gov/risk/

Note the only truly devastating asteroid we have a potential impact with right now is Apophis, NASA says the likelihood of an impact is near zero, but the Russians disagree.

Snick · Aug 17, 2011

DrunkenLilacs said:
Okay, so, I have this WIP that has a scientific element. Basically, an asteroid that was thought to have passed by has circled the earth and now has come back around, threatening to hit it. Is that plausible? Can an asteroid do that?

That would be very unlikely, because asteroids that approach the Earth have orbits that are not closely closed, so the thing would orbit away from the Earth, not return. There are ways to steer an asteroid, but that's for another question.

Also, let's say the asteroid is the size of London. How big would the damage be? I wa thinking of having it destroy one part of the U.S.--the west-- its surrounding areas and possibly states--once the impact happens, everyone around those areas die, but there's still a good amount of the country that's still in tact, for now at least.

Yeah, have it hit California and set off the San Andreas Fault nad maybe a few others. Or yyou could have it hit Yellowstone Park and set off the Yellowstone Caldera. That would result in massive dust clouds that would surround the Earht for a long time.

I've read a lot into the aftermath--fireballs, radiation, a lot of wind, ejecta--but I want to know if the impact of an asteroid that big would just kill everyone in a short amount of time, if there was no use of evacuation, if let's say, there's not exactly a safe zone to evacuate to.

Am I making sense? I feel like I'm rambling. I just want to know if one: it's plausible for an asteroid to orbit around the earth, come back and threaten to hit (and if scientists would catch it early on and do some thing about it); and two, what the impact would be like.

An asteroid the size of Greater London hitting the Earth would be a major catastrophe for the whole world.

It's just a small portion of my WIP--I'm not going to go into detail about the asteroid in the story, but I think it would be nice if I knew it was plausible.

The world needs a great disaster. You might want to read "Lucifer's Hammer" by Larry Niven and Jerry Pournelle. It is about the aftermath of a comet hitting the Earth. I can't remember whaere it hit, but it was the end of civilization as we know it; and it was't all that big.

You'll have to have it pass close to anther planet that would steer it back at Earth. Or you could forget about the initial near miss. Or you could have NASA try to break it up with bombs that would make it come straight at the Earth.

Drachen Jager · Aug 17, 2011

DrunkenLilacs said:
Yeah, that's what I was thinking, too. And we probably have the technology to alter its course. *sigh* Armageddon was a terrible movie...what they did to stop the asteroid was implausible, also.

As the disagreement over Apophis shows we don't know whether it will hit or not. Also, scientists cannot calculate for factors such as a collision with a smaller body (another asteroid or comet) which could alter the course significantly. Your plot is still plausible.

IF we had a case similar to Apophis, where one country thinks there's a slim chance but NASA says the chance is zero until it's too late we wouldn't be able to mount an anti-asteroid mission in time, that sort of thing would take six months to a year minimum, probably more like two years or longer.

DrunkenLilacs · Aug 17, 2011

Drachen Jager said:
As the disagreement over Apophis shows we don't know whether it will hit or not. Also, scientists cannot calculate for factors such as a collision with a smaller body (another asteroid or comet) which could alter the course significantly. Your plot is still plausible.

IF we had a case similar to Apophis, where one country thinks there's a slim chance but NASA says the chance is zero until it's too late we wouldn't be able to mount an anti-asteroid mission in time, that sort of thing would take six months to a year minimum, probably more like two years or longer.

That's a really good point. We are human, after all, and sometimes we might not make the right assumptions. Thanks Drachen. I didn't think of this, and I'm so glad you brought it up. That way, my MC's can still get a sense of shock, rather than just having expected their deaths.

PrincessofPersia · Aug 17, 2011

DrunkenLilacs said:
Here are the trailers, if anyone's interested:
Another Earth: http://www.youtube.com/watch?v=N8hEwMMDtFY
Melancholia: http://www.youtube.com/watch?v=wzD0U841LRM

But thanks, PrincessofPersia!

No problem. I didn't watch Another Earth, but the Melancholia trailer was awful IMHO. Not to sound disgusting, but the only thing that looks appealing about the movie is that I get to look at Kirsten Dunst.

But no. We'd know if there was another planet there.

Drachen Jager said:
A couple of impact simulators.

http://impact.ese.ic.ac.uk/ImpactEffects/

http://www.armageddononline.org/asteroid-impact-simulator.html

Yes it is possible for an asteroid to loop around that way, though the boffins at NASA, ESA and the Russian space program track them and have a pretty good idea where they'll end up.

Loop around in what way? I was assuming the proposed event would be the asteroid passing Earth, then spinning around and coming back like a yo-yo. I may have misunderstood though.

Note the only truly devastating asteroid we have a potential impact with right now is Apophis, NASA says the likelihood of an impact is near zero, but the Russians disagree.

No offense, but the Russians don't have a great track record. I'd trust NASA first. That said, if the Apophis object passes within the critical zone, I'm assuming that we'd work together to alter its orbit if there is even a slight chance that it will hit. I doubt we'd take no action if it weren't clear that it'd miss us.

Drachen Jager said:
As the disagreement over Apophis shows we don't know whether it will hit or not. Also, scientists cannot calculate for factors such as a collision with a smaller body (another asteroid or comet) which could alter the course significantly. Your plot is still plausible.

IF we had a case similar to Apophis, where one country thinks there's a slim chance but NASA says the chance is zero until it's too late we wouldn't be able to mount an anti-asteroid mission in time, that sort of thing would take six months to a year minimum, probably more like two years or longer.

I doubt we'd figure it out for sure with such little time left. Apophis (1997 XF11) was discovered in December 1997. That's 31 years before it's set to fly by us. We already have a relatively good idea about where it will be the next time. An orbit-altering event would have to happen pretty close to when it is going to pass us, and there would be an astronomically small chance of it being altered to strike us.

Snick · Aug 17, 2011

PrincessofPersia said:
Loop around in what way? I was assuming the proposed event would be the asteroid passing Earth, then spinning around and coming back like a yo-yo. I may have misunderstood though.

It couldn't act like a yo-yo, because there is no attachment, and the gravity is no where near enough to make that happen. Depending to the mass and velocity of the asteroid, it might be possible for it to approach the Moon closely and loop around it and come straight back. I don't know whether the Moon's gravity is enough for that, but Venus has enough gravity, and the sequence of the asteroid ploughing through the Venusian clouds and back at the Earth could be a great sequence. That wouldn't be enough to destroy the cloud cover of Venus, but it could diminish it.

PrincessofPersia · Aug 17, 2011

Snick said:
It couldn't act like a yo-yo, because there is no attachment, and the gravity is not where near enough to make that happen. Depending to the mass and velocity of the asteroid, it might be possible for it to approach the Moon closely and loop around it and come straight back. I don't know whether the Moon's gravity is enough for that, but Venus has enough gravity, and the sequence of the asteroid ploughing through the Venusian clouds and back at the Earth could be a great sequence. That wouldn't be enough to destroy the Cloud cover of Venus, but it could diminish it.

Yeah, I was saying that a yo-yo like action couldn't happen. Hence my confusion about DL's post. The Moon's gravity isn't enough to do that. YU55 is only 400 metres across, and the gravity of even the Earth isn't enough to alter its course in any significant way.

JennieRose8 · Aug 17, 2011

Your story sounds really interesting. What is the main plot, if you don't mind me asking?

GeorgeK · Aug 17, 2011

DrunkenLilacs said:
Okay, so, I have this WIP that has a scientific element. Basically, an asteroid that was thought to have passed by has circled the earth and now has come back around, threatening to hit it. Is that plausible? Can an asteroid do that?

The short answer is that no, an asteroid is not likely to do that. The long answer is that yes it could if all the conditions were right. That all the conditions to be right is so low that were it to happen the people watching the sky would likely assume the asteroid to be under intelligent control. So they'd probably be on the phone to seti before the pentagon.

DrunkenLilacs said:
Also, let's say the asteroid is the size of London. How big would the damage be?
Extinction level

DrunkenLilacs said:
I wa thinking of having it destroy one part of the U.S.--the west-- its surrounding areas and possibly states--once the impact happens, everyone around those areas die, but there's still a good amount of the country that's still in tact, for now at least.

I've read a lot into the aftermath--fireballs, radiation, a lot of wind, ejecta--but I want to know if the impact of an asteroid that big would just kill everyone in a short amount of time, if there was no use of evacuation, if let's say, there's not exactly a safe zone to evacuate to.

Am I making sense? I feel like I'm rambling. I just want to know if one: it's plausible for an asteroid to orbit around the earth, come back and threaten to hit (and if scientists would catch it early on and do some thing about it); and two, what the impact would be like.

It's just a small portion of my WIP--I'm not going to go into detail about the asteroid in the story, but I think it would be nice if I knew it was plausible.

Help? Please and thank you?

Drachen Jager · Aug 17, 2011

PrincessofPersia said:
Yeah, I was saying that a yo-yo like action couldn't happen. Hence my confusion about DL's post. The Moon's gravity isn't enough to do that. YU55 is only 400 metres across, and the gravity of even the Earth isn't enough to alter its course in any significant way.

I was thinking of a gravity slingshot as several people above have pointed out. I assume that's the kind of scenario DL is thinking about, because if a statement or question is ambiguous, I prefer to assume the person talking is smart rather than stupid.

blacbird · Aug 17, 2011

DrunkenLilacs said:
Okay, so, I have this WIP that has a scientific element. Basically, an asteroid that was thought to have passed by has circled the earth and now has come back around, threatening to hit it. Is that plausible? Can an asteroid do that?

Yes, although not likely in a short term manner. The gravitational influence of the Earth could alter an asteroid's orbit in such a manner that it might be drawn into a closer path that could ultimately result in a collision. Exactly this thing happened with the Shoemaker-Levy comet that broke up and slammed into Jupiter in 1994.

DrunkenLilacs said:
Also, let's say the asteroid is the size of London. How big would the damage be?

The end of human life, and probably most living things on the planet. The asteroid figured to have resulted in the demise of dinosaurs, pterosaurs, mososaurs, ammonites and multitudes of other life forms 65 million years ago is believed to have been about 10 km in diameter. London is about 60km in width.

The volume math works out to be 10X10X10 km = 1000 cubic cm. 60X60X60 km = 216,000 cubic km, or 216 times the volume of the dinosaur killer.

It would be very bad.

caw

DrZoidberg · Aug 19, 2011

What's with the looping around? Can't you just have a previously unknown asteroid simply turn up and slam into Earth. That's be totally believable and won't violate any known physics.

But you do need to do your homework regarding the mass and calculated damage. Objects travelling at high speeds, like stuff pulled in by our gravitational field, do much more damage than slow objects. An asteroid the size of London would do incalculable damage and probably throw up a dustcloud that would block the sun for years, killing most if not all plant life, and the creatures living off it.

Mark G · Aug 19, 2011

I saw a documentary on this. The idea of sending a rocket to meet the asteroid and destroy it probably wouldn't work. According to the program (I believe it was one of those PBS things or History Channel), an explosion wouldn't change the MASS of the meteor; it would just turn it into a big, roiling storm of smaller pieces. Their mass would hold them together; and their path wouldn't change significantly. So instead of getting hit by a single BIG meteor, we'd get hit by hundreds of smaller meteors at the same time. So they were leaning towards the idea of placing "guidance rockets" on the meteor to change its orbit. That works a lot better if you have a one-piece meteor.

Tsu Dho Nimh · Aug 19, 2011

http://en.wikipedia.org/wiki/Meteor_Crater is about 1,200 m (4,000 ft) in diameter, 170 m deep (570 ft), and is surrounded by a rim that rises 45 m (150 ft) above the surrounding plains. The center of the crater is filled with 210–240 m (700–800 ft) of rubble lying above crater bedrock.

It was made by a meteorite about 50 meters across.

Chicxulub crater is more than 180 km (110 mi) in diameter, the meteorite was estimated as at least 10 km (6 mi) in diameter.

A meteor "the size of London" ... that's a hundred miles in diameter? Unless you want to take out entire continents and maybe cause global extinction and rupture the earth's crust, don't throw objects that large at the bottom of our gravity well.

Anyway, it can't do a near miss and loop around for another pass because of the physics of the encounters.

DrunkenLilacs · Aug 19, 2011

Thanks for all the help guys! I've made the asteroid A LOT smaller. Again, thanks, I've got it!

blacbird · Aug 19, 2011

DrunkenLilacs said:
I've made the asteroid A LOT smaller.

You need to talk to NASA about how you did this.

caw

Evice · Aug 20, 2011

Maybe if it was a alien planet to planet missile disguised as a asteroid, it might pass by to catch us off guard and then loop back to get us!

Calling all scientists and science buffs (:

DrunkenLilacs

Growing tipsier as we speak

mirandashell

BunnyMaz

Ruining your porn since 1984

PrincessofPersia

Mutive

Blissfully Clueless

DrunkenLilacs

Growing tipsier as we speak

PrincessofPersia

DrunkenLilacs

Growing tipsier as we speak

Drachen Jager

Professor of applied misanthropy

Snick

Drachen Jager

Professor of applied misanthropy

DrunkenLilacs

Growing tipsier as we speak

PrincessofPersia

Snick

PrincessofPersia

JennieRose8

GeorgeK

ever seeking

Drachen Jager

Professor of applied misanthropy

blacbird

DrZoidberg

aka TomOfSweden

Mark G

Author of Reborn to Bite

Tsu Dho Nimh

DrunkenLilacs

Growing tipsier as we speak

blacbird

Evice