4 ms·

How does the math change when you take into account the fact that Earth exerts a gravitational pull on the asteroid?

Skunkleton 7y ago
Interesting question, not sure. As the speed of the astroid is goes up, the relevance of gravity goes down. As the speed goes down, the damage it can do also goes down, and also reduces the probability of an encounter.
quickthrower2 7y ago
And does that make it more likely to miss? Ie it gets slung around by gravity instead of hitting?
lutorm 7y ago
The degree of gravitational focusing depends on the speed of the incoming object, but I seem to recall that for typical interplanetary velocities it's of order 1, ie not huge.
dmckeon 7y ago
It may not change this encounter much, but it could change the orbit just enough for some future earth-orbit crossing - as could the gravitational effect of any of the other planets, their moons, and all the other asteroids change the orbits of anything out there. Solar systems can be messy places, over geologic time frames. Sometime, sooner or later, we will have a significant impact.
kryogen1c 7y ago
Thinking out loud time! My favorite! To matter for a single pass, the object must be small and/or traveling slowly. Otherwise, itll just keep on cruising. Iteratively is a different story. Many objects repeatedly cross earths path. How that orbit changes over time i suppose is a function of the other gravity wells the objects pass when they arent near earth. I expect there are so many confounding gravities that only a certain belt\torus exists in the universe where, inside that torus, space stuff is capable of running into us. Side note: this article is clickbaity because it implies no one knew asteroids almost crash into us without us knowing, but thats not true. People know. There are hard reset buttons floating around in space and we might just press one without warning. https://en.m.wikipedia.org/wiki/Potentially_hazardous_object https://en.m.wikipedia.org/wiki/Potentially_hazardous_object
- probablybroken 7y ago
  Why would the size of the object matter in this instance?
  - kryogen1c 7y ago
    Mass, not really size. The smaller the object relative to earth, the more its course is changed by earths gravity.
    - probablybroken 7y ago
      You may want to refer to Galileo's leaning tower of pisa experiment...
gamedori 7y ago
It probably has no effect: objects that are not in stable orbits around the earth are going to be in hyperbolic orbits relative to the Earth's gravitational field. A dangerous asteroid would need a periapsis lower than the Earth's radius by a certain amount to hit the Earth, so the risk of collision is still roughly proportional to Area. If gravity is a factor I would expect it to be a high order term. Atmospheric effects are probably more significant.

Interesting question, not sure. As the speed of the astroid is goes up, the relevance of gravity goes down. As the speed goes down, the damage it can do also goes down, and also reduces the probability of an encounter.

quickthrower2 7y ago

And does that make it more likely to miss? Ie it gets slung around by gravity instead of hitting?

lutorm 7y ago

The degree of gravitational focusing depends on the speed of the incoming object, but I seem to recall that for typical interplanetary velocities it's of order 1, ie not huge.

dmckeon 7y ago

It may not change this encounter much, but it could change the orbit just enough for some future earth-orbit crossing - as could the gravitational effect of any of the other planets, their moons, and all the other asteroids change the orbits of anything out there. Solar systems can be messy places, over geologic time frames. Sometime, sooner or later, we will have a significant impact.

kryogen1c 7y ago

Thinking out loud time! My favorite! To matter for a single pass, the object must be small and/or traveling slowly. Otherwise, itll just keep on cruising. Iteratively is a different story. Many objects repeatedly cross earths path. How that orbit changes over time i suppose is a function of the other gravity wells the objects pass when they arent near earth. I expect there are so many confounding gravities that only a certain belt\torus exists in the universe where, inside that torus, space stuff is capable of running into us. Side note: this article is clickbaity because it implies no one knew asteroids almost crash into us without us knowing, but thats not true. People know. There are hard reset buttons floating around in space and we might just press one without warning. https://en.m.wikipedia.org/wiki/Potentially_hazardous_object https://en.m.wikipedia.org/wiki/Potentially_hazardous_object

probablybroken 7y ago
Why would the size of the object matter in this instance?
- kryogen1c 7y ago
  Mass, not really size. The smaller the object relative to earth, the more its course is changed by earths gravity.
  - probablybroken 7y ago
    You may want to refer to Galileo's leaning tower of pisa experiment...

gamedori 7y ago

It probably has no effect: objects that are not in stable orbits around the earth are going to be in hyperbolic orbits relative to the Earth's gravitational field. A dangerous asteroid would need a periapsis lower than the Earth's radius by a certain amount to hit the Earth, so the risk of collision is still roughly proportional to Area. If gravity is a factor I would expect it to be a high order term. Atmospheric effects are probably more significant.