Spaceships and astronomy
#77
Re: Spaceships and astronomy
Earth has another moon!
NASA says it isn't, but then they're also trying to tell us that Pluto isn't a planet.
NASA says it isn't, but then they're also trying to tell us that Pluto isn't a planet.
Last edited by Pulaski; Jun 16th 2016 at 8:46 pm.
#78
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Joined: Feb 2009
Location: Fox Lake, IL (from Carrickfergus NI)
Posts: 49,598
Re: Spaceships and astronomy
Earth has another moon!
NASA says it isn't, but then they're trying to tell us that Pluto isn't a planet either.
NASA says it isn't, but then they're trying to tell us that Pluto isn't a planet either.
#79
Re: Spaceships and astronomy
Earth has another moon!
NASA says it isn't, but then they're also trying to tell us that Pluto isn't a planet.
NASA says it isn't, but then they're also trying to tell us that Pluto isn't a planet.
#80
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Joined: Feb 2009
Location: Fox Lake, IL (from Carrickfergus NI)
Posts: 49,598
Re: Spaceships and astronomy
#81
Re: Spaceships and astronomy
There appears to be too little information to rule out that possibility at the moment.
It's interesting that we can look at stars that are billions of lightyears away/ years old, but we can suddenly find a sizeable chunk of rock that we didn't know is whizzing around in our own back yard.
It's interesting that we can look at stars that are billions of lightyears away/ years old, but we can suddenly find a sizeable chunk of rock that we didn't know is whizzing around in our own back yard.
#82
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Joined: Feb 2009
Location: Fox Lake, IL (from Carrickfergus NI)
Posts: 49,598
Re: Spaceships and astronomy
There appears to be too little information to rule out that possibility at the moment.
It's interesting that we can look at stars that are billions of lightyears away/ years old, but we can suddenly find a sizeable chunk of rock that we didn't know is whizzing around in our own back yard.
It's interesting that we can look at stars that are billions of lightyears away/ years old, but we can suddenly find a sizeable chunk of rock that we didn't know is whizzing around in our own back yard.
#83
Re: Spaceships and astronomy
There appears to be too little information to rule out that possibility at the moment.
It's interesting that we can look at stars that are billions of lightyears away/ years old, but we can suddenly find a sizeable chunk of rock that we didn't know is whizzing around in our own back yard.
It's interesting that we can look at stars that are billions of lightyears away/ years old, but we can suddenly find a sizeable chunk of rock that we didn't know is whizzing around in our own back yard.
#84
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Joined: Feb 2009
Location: Fox Lake, IL (from Carrickfergus NI)
Posts: 49,598
Re: Spaceships and astronomy
Anyway, Newton's first law is what is at work here. Unless it is pushed out of its orbit by some external gravitational influence, it will stay where it is quite happily. Even then it's a crap shoot as to whether said influence would not just push it out of orbit and away from Earth anyway.
More of a concern are as yet undiscovered or untracked Near Earth Asteroids, or unobserved comets from the Kuiper Belt stopping by to say hello. Luckily, Jupiter helps keep a lot of these objects away from us. We do love Jupiter
#86
Re: Spaceships and astronomy
Agreed, with statistics playing a strong supporting roll.
I have just done a rough calculation, based on an orbit of radius 9 million miles and a size of the earth as a disc of 8,000 miles across. If the asteroid flew off in a totally random direction, the probability of it coming in our direction (it hitting a disc of 50 million sqmiles on the surface of a sphere with the radius of its orbital distance from earth) is 1.64×10^-14, which I think is less than 1 in 60 trillion. In any case, the reality is that if it gets "nudged" it is far more likely to shoot off into space that come in our direction.
I have just done a rough calculation, based on an orbit of radius 9 million miles and a size of the earth as a disc of 8,000 miles across. If the asteroid flew off in a totally random direction, the probability of it coming in our direction (it hitting a disc of 50 million sqmiles on the surface of a sphere with the radius of its orbital distance from earth) is 1.64×10^-14, which I think is less than 1 in 60 trillion. In any case, the reality is that if it gets "nudged" it is far more likely to shoot off into space that come in our direction.
#87
Re: Spaceships and astronomy
Agreed, with statistics playing a strong supporting roll.
I have just done a rough calculation, based on an orbit of radius 9 million miles and a size of the earth as a disc of 8,000 miles across. If the asteroid flew off in a totally random direction, the probability of it coming in our direction (it hitting a disc of 50 million sqmiles on the surface of a sphere with the radius of its orbital distance from earth) is 1.64×10^-14, which I think is less than 1 in 60 trillion. In any case, the reality is that if it gets "nudged" it is far more likely to shoot off into space that come in our direction.
I have just done a rough calculation, based on an orbit of radius 9 million miles and a size of the earth as a disc of 8,000 miles across. If the asteroid flew off in a totally random direction, the probability of it coming in our direction (it hitting a disc of 50 million sqmiles on the surface of a sphere with the radius of its orbital distance from earth) is 1.64×10^-14, which I think is less than 1 in 60 trillion. In any case, the reality is that if it gets "nudged" it is far more likely to shoot off into space that come in our direction.
#88
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Joined: Feb 2009
Location: Fox Lake, IL (from Carrickfergus NI)
Posts: 49,598
Re: Spaceships and astronomy
It wouldn't work like that in practice. A random object would have to be essentially on a collision course with Earth in order to come straight at us like that, at which point it wouldn't matter what it hits on the way.
#89
Re: Spaceships and astronomy
I'm just thinking, many random objects are on a collision course with Earth, but get burned up in the atmosphere. If one were to hit the orbiting astroid (unlikely but possible) its trajectory would likely include a liaison with Earth.
#90
Re: Spaceships and astronomy
If anything gets close enough to that chunk of rock to move it out of earth's orbit it will (i) be pretty much random in direction, and (ii) is by far most likely to put it (back) into orbit around the sun, which is likely where it came from in the first place.
You've been watching too many sci-fi movies.
Last edited by Pulaski; Jun 17th 2016 at 5:11 pm.