possible Earth collision detection

[brandbll]

I have a question about our ability to detect objects that could possibly strike the Earth. It seems like we do a good job keeping track of objects in our own solar system. But couldn't it be possible for something outside of our solar system to strike us from a direction that we really aren't watching? For example, recently when Xena was discovered i remember reading that it took so long to discover because of it's wacky orbit and that is why no one was looking for it. <br /><br />So, i guess what i'm asking is, what are the odds we could completely miss something that could smash into Earth? <div class="Discussion_UserSignature"> <p><font size="3">You wanna talk some jive? I'll talk some jive. I'll talk some jive like you've never heard!</font></p> </div>

 

[harmonicaman]

Not only do we have to look for for objects that are not in the plane of the elliptic (or residing in wacky orbits), but we have to be alert for long period comets that comes at us from behind the Sun! I think that's where the most danger lies; an object that comes at us undetected due to the Sun's glare...<br /><br />

 

[dragon04]

<font color="yellow">but we have to be alert for long period comets that comes at us from behind the Sun!</font><br /><br />In our yearly trek around the sun, we get an omnidirectional look for just such objects.<br /><br />I would also think that aberrant objects inbound from outside the solar system at extreme inclinations with respect to the ecliptic would be primarily influenced by the sun's gravity well, although I don't have the expertise in the mechanics involved to make more than uneducated assumptions.<br /><br />Over the course of the several billions of years the solar system has existed, all objects affected by the sun's gravity have pretty much settled into stable, predictable orbits, I would assume.<br /><br />Perhaps one of our more expert posters could explain something to me.<br /><br />I've read a great deal about massive objects interacting with and perturbing Oort cloud objects.<br /><br />As an example, let's say that an object as massive as Barnard's Star (which in time will pass relatively close to our solar system) cruises by at an arbitrary distance of 1 LY.<br /><br />How is it that BS can "knock" an Oort body towards the sun as opposed to pulling it out of the Oort cloud?<br /><br />To the best of my knowledge, gravity is not repulsive in nature, but rather attractive in all cases. Is it because a massive and passing body steals orbital velocity from the Oort objects? <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[the_unknown]

first off, there are new comets found every year (or more frequent) and some comets have very eliptical paths and take many years (like 86, i believe hale bop) to orbit the sun. a comet coming from the far side of the sun that was impossible to see until it passed the sun enough to make a bright imprint on the horizon at sunset or sunrise would give us the least warning time for a collision. this is only taking in consideration our solar system's objects. If moving at a median speed for a comet, we would have anywhere from about 2 months to 6 months before the collision and, of course, even less time to do something about it.<br /><br />one more thing... an object traveling near the speed of light will actually push objects (stars, oort cloud objects, galaxies) away from them. even objects moving fractions slower than the speed of light will also push objects away, just not as much as an object moving close to the speed of light. look in the archives of articles here and find one dealing with merging galaxies and you will see that fact.<br />

 

[brandbll]

I'm talking about something like an asteroid though that might come at us at a wierd angle from outside the solar system. Do we have a means for detecting something like that?<br /><br />"one more thing... an object traveling near the speed of light will actually push objects (stars, oort cloud objects, galaxies) away from them. "<br /><br />So you are saying a small object would push our sun out of it's way because of its speed? <div class="Discussion_UserSignature"> <p><font size="3">You wanna talk some jive? I'll talk some jive. I'll talk some jive like you've never heard!</font></p> </div>

 

[qso1]

the_uNKNown:<br />"one more thing... an object traveling near the speed of light will actually push objects (stars, oort cloud objects, galaxies) away from them. "<br /><br />Me:<br />To the best of my knowledge, no physical astronomical object has ever been detected travelling near light speed and a small one could not repel a galaxy even if it were travelling at SOL. As an example, typical comet velocities are roughly .01 % light speed, nowhere near the speed of light.<br /><br />An object coming in from the far side of the sun is more myth than fact. It has already been explained that we orbit the sun so there is no far side as it were. The closest thing to that would be an object coming in on the opposite of the sun relative to our current position. But at some 60,000 mph, the object is not travelling fast enough to get to us so as not to be seen until the last possible minute. The object would eventually pass near the sun and be about 93 million miles from us as it passes from the opposite to the same side of the sun. This would give us detection time but with no known defense system in place, we would be hard pressed to do anything about the potential impact. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

brandbll:<br />While its possible that something could come in from a weird angle undetected, its usually the case that astronomers world wide, professional and amateur alike, are constantly scanning all areas of sky for the next comet or asteroid passage. A good example of this can be seen at the thread listed below.<br /><br />News flash: Earth has a "second moon."<br /><br />Check out the weird orbit which at times would put the object in extreme southern or northern latitudes for prospective observations. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>