Thread: Interstellar meteorites

I was thinking, is the reason we don't find interstellar meteorites on earth, due to their speed of entry, or they just don't hit us?

Do interstellar objects always explode on hitting the atmosphere leaving no trace?

The total energy of impact with the atmosphere and ground is proportional to the velocity squared.
However, the rate of energy transfer (power) from ram-air pressure in the atmosphere is proportional to the cube of the velocity.

If local meteors come in at 20 km/s to 70 km/s, but interstellar stuff can come in at 550 km/s (sun vel through space), then they could be heated a thousand times hotter by ran-air effects.

Is this hot enough to generate soft x-rays that will penetrate the meteor causing it to explode at altitude

May be it's because they are rare and even if you get one how do you tell the difference? May be it's good that we don't meet much interstellar space phenomena.

Originally Posted by ~Mark~M~

May be it's because they are rare and even if you get one how do you tell the difference? May be it's good that we don't meet much interstellar space phenomena.

Yes, but for every free-floating planet out there, how many comets and large asteroids?
For every large object, how many smaller objects that vanish in a flash on hitting the upper atmosphere?

What I really want comments on, is the idea that these interstellar objects are travelling fast enough to generate megawatts of soft x-rays, that penetrate the meteor causing it to explode as inclusions vaporise.

I also think that such objects are exceptionally rare. Though comets leaving our solar system are common.

Another reason why such objects are not hitting Earth is the following: Concentration of mass in our solar system. Outer planets (gas giants) are pulling these objects away from Earth. Please, also keep in mind, most of our solar system is an empty space.

Originally Posted by PetTastic

I was thinking, is the reason we don't find interstellar meteorites on earth, due to their speed of entry, or they just don't hit us?

Mostly they are just not there. Free floating rocks in interstellar space are exceedingly rare (at least compared to free floating rocks near the Sun.)

Originally Posted by billvon

Originally Posted by PetTastic

I was thinking, is the reason we don't find interstellar meteorites on earth, due to their speed of entry, or they just don't hit us?

Mostly they are just not there. Free floating rocks in interstellar space are exceedingly rare (at least compared to free floating rocks near the Sun.)

Yes, I agree, but estimates on the amount of interstellar material vary by many orders of magnitude.
I am interested in how to interpret what evidence, there is.

If most near-Earth objects are travelling at +-10km/s relative to us (orbits between mars and Venus), until they fall into the Earth's gravity, how hard is it to spot something going past 70-100 times faster?

Originally Posted by BlasW

I also think that such objects are exceptionally rare. Though comets leaving our solar system are common.

Another reason why such objects are not hitting Earth is the following: Concentration of mass in our solar system. Outer planets (gas giants) are pulling these objects away from Earth. Please, also keep in mind, most of our solar system is an empty space.

I agree these object are not very common, but our solar system is so tiny on the scale of interstellar space, everyone we do detect hints at a massive population out there.

The only way something travelling at interstellar velocities, is going to notice the existence of the outer planets is if they score a direct hit.
Slower material, that may be moving in the same direction as our system is unlikely to approach through the plane the planets orbit in.
If it comes in thought the planets, Jupiter takes 11 years to do an orbit, giving plenty of time for stuff to come in while it is on the other side of the system.

Originally Posted by PetTastic

Originally Posted by ~Mark~M~

May be it's because they are rare and even if you get one how do you tell the difference? May be it's good that we don't meet much interstellar space phenomena.

Yes, but for every free-floating planet out there, how many comets and large asteroids?
For every large object, how many smaller objects that vanish in a flash on hitting the upper atmosphere?

What I really want comments on, is the idea that these interstellar objects are travelling fast enough to generate megawatts of soft x-rays, that penetrate the meteor causing it to explode as inclusions vaporise.

Why do you think the objects would be traveling fast? The Cosmic Rays include a few fast moving protons, some even approaching the speed of light, but it is theorized that the fastest moving protons only maintain that speed for a limited distance after they're set in motion because they interact with the CMBR, and that slows them down.

A macro-sized object, in turn, would be slowed down gradually by constant collisions with the Cosmic Rays.

Besides that, the kinds of forces that are capable of accelerating a macro-sized object to extremely high speeds also tend to shatter it to bits. Even forces like gravity have that effect if they're very strong, because of tidal forces.

Originally Posted by kojax

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Why do you think the objects would be traveling fast? The Cosmic Rays include a few fast moving protons, some even approaching the speed of light, but it is theorized that the fastest moving protons only maintain that speed for a limited distance after they're set in motion because they interact with the CMBR, and that slows them down.

A macro-sized object, in turn, would be slowed down gradually by constant collisions with the Cosmic Rays.

Besides that, the kinds of forces that are capable of accelerating a macro-sized object to extremely high speeds also tend to shatter it to bits. Even forces like gravity have that effect if they're very strong, because of tidal forces.

I was assuming interstellar stuff would be moving at speeds on the same scale as the stars.
The Sun is relativly slow moving star only doing 550km/s ( 0.31 AU per day)