A question base of Skies of Pern, and rocks from space.

[GinnyStar]

I was reading a story on ff.net, and know several members here are on there, and are better at set up informaton to send PM via e.g. (dot) explaning it. then I can. PS I add the spoiler for this fan written one for its has a few thinks in it which in my book.
author, leavesfallingup,
Title: Dragon's Destiny
Chapter: 9
Story URL: http://www.fanfiction.net/s/5777090/9/
Author URL: http://www.fanfiction.net/u/1692535/

the writer in question had a one that stump me. So I got a question for you.
via this writer, and I was thinking 'What if this hit Pern, what kind of impace would it be.'

I helped via Hans site to fix an spot.

hanks for the information. Are there any good links that might help me. I
have been using the old fashioned method (notes kept in a notebook) and I've
missed quite a bit of important information.

She is looking for more on

As long as we're at it, do you have any significant information about the
Western Continent? It is key to my plot, and I don't want to get the
information wrong.

More on the reply to your comments on chapter 10. If a cart (or car) sized
asteroid struck dead-center in the sand, then the entire surrounding area
would be devastated. As an example go to Crater Valley in Panama. The main
impact there was approximately the size of a schoolbus, but the crater is 18.2
square kilometers.

I think she fogot one thing the effect of hitting the sand, and bay its self it in the middle of Half-Circle Sea Hold.
I wish my writing was clear any thoughts on this bit? I know the one that was in SoP hit water, and the effect of the wave at Sunrise Clift Sea Hold.
Also depend on how close to sand/water it is.

Also you folks know that I can't type for long. "Sighing" I love helping folks I just wish my writting skils were better.

[Cavatica]

...can anybody translate that for me?

[Joz]

1. Any info on the western continent? - I don't think there is, however. I'm waiting for the next book to come out (one day!) and I'm hoping there will be more info on it then. If I recall correctly, the western continent was originally a fan invention, from a role-playing game, and Anne took it on.

2. Any useful information about the effects of meteor impacts, including what would happen if it hit different substrates, such as sand, or rock. We already see an example of what would happen if an asteroid hit water in Skies of Pern.

Somewhere I have some info on that, relating size and mass of asteroid to size of crater formed. But this will be affected by a planet's gravity. Craters on the moon have larger central peaks as the lesser gravity allows for greater rebound. But since Pern is similar to Earth this probably wouldn't be a factor in the story.

[Eriflor]

The Western Continent is visible on the left side of the map in Skies of Pern. It's described as 'two landmasses, a wide inlet almost completely separating them except for a straggle of boulders making a bridge at the northern end' (page 402 in the Ballantyne Books paperbook --- end of the section INTERIM AT BENDEN AND ELSEWHERE).

Actually, on the map it looks more like 2 islands very close together, so the boulders may be under water at times.

Eriflor.

[GinnyStar]

Thanks folks, for the information. for some reason I can't get the coding as it not part of FF.net then it gets removed.

[StevenB]

GinnyStar, the damage resulting from the impact of an asteroid doesn't just depend on how large it is. It depends on what it is made of, how fast it is travelling and what kind of material it hits. So there is no one true answer to your query. The speed of impact will depend on where the asteroid has come from - objects in a retrograde or hyperbolic orbit will be the most damaging because they will hit faster.

What happens also depends on what the asteroid is made of. If an asteroid is made of loose rubble it could break up into smaller pieces when entering the atmosphere (that's not necessarily a good thing because it could cause damage over a wider area, like the difference between a single bullet and a shotgun round; it is a good thing if the pieces become small enough to vapourise). An asteroid made of volatile materials (such as ice and frozen gases) would probably vapourise or explode in the atmosphere and never hit the ground (the Tunguska event last century was supposed to be one of those situations).

The material the asteroid hits also makes a difference. The sea is the worst place for an asteroid to hit, since it would create a tsunami that could devastate a wide area of the globe. I am not sure about sand. During a high speed impact it could act like a fluid and behave rather like water, so you could get a short-lived "sand tsunami" (which might explain the comment about an impact in sand generating an unusually large crater). But it would be worth asking some geologists and impact specialists.

[P'ter]

In industry, sand with air blown through it acts as a liquid. So, you might get almost no crater at all as it would fill back in.

[GinnyStar]

Thanks both SteveB and P'ter for the information.

[StevenB]

You're welcome Ginny. As I said in my visitor post, I don't have time to look up any references at the moment, but you could try Googling "cosmic impact" or "asteroid collision" and see what you find.

It's interesting how materials behave differently when shocked supersonically. I recently went to a lecture by the engineers designing the next car to attempt the world land speed record. At such high speeds, the ground underneath the car acts like a fluid, so the wheels are designed more like the rudders of a ship than the wheels of an ordinary car.

By the way, when I said "sand tsunami" I meant that would happen only during the short time that the sand is shocked and behaving like a fluid. A tsunami in the ocean can travel thousands of miles, but any such wave in the sand will reach a certain distance and then stop. Would wet sand behave differently from dry sand?

The simplest way to decide how devastating an impact would be is to work out how much energy is available using the kinetic energy formula (half mass times velocity squared). That energy could be compared to the energy generated by an atomic bomb of a certain number of megatons. As an approximation you could assume the object is a spherical lump of iron of the size you want travelling at escape velocity (~10 km/s).

[Cheryl]

Wet sand would definitely behave different from dry sand. I think your "sand tsunami" scenario is more likely to happen with dry sand. Wet sand, when shocked, liquifies but I don't think it would transmit the shock wave far.

In earthquakes at least, wet sand acts like quicksand and anything built on top of it is going to sink and/or topple. There's a notable case of this happening in Japan where some brand-new buildings suffered no structural damage but sunk a bit and tilted, rendering them completely uninhabitable:

[GinnyStar]

Thanks all for the useful information.

[StevenB]

Thanks Cheryl.

[Multi-Facets]

Yikes. Those apartments are worse off than the Leaning Tower of Pisa. ^0_o^