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A Rock Moves In Space
theBrownfury writes: "The BBC is reporting here that
a very large Earth collision course asteroid has been discovered. This asteroid, NT7,
was first observed on July 5th and current data suggests an impact date of
February 1st, 2019. NT7 is 2kms wide and on date of impact will be approaching
Earth at 28km/s. An asteroid of this size is large enough to cause continent
wide destruction. However astronomers are still cautious in reporting this
asteroid as the orbit of NT7 has not been fully verified. Current data on
NT7's orbit suggests it orbits the Sun every 837 days and travels in a tilted
orbit from about the distance of Mars to just within the Earth's orbit." The BBC article's headline (and accompanying illustration) are more alarming than the story itself seems to warrant: this asteroid has been given a 0.06 on the Palermo technical scale, which means it shouldn't bump getting run over by a llama off your list of worries.
Check out the 3d view here.
Just fast-forward to Feb-1 2019, set the center on earth, and zoom in.
1. mine it for data;
...and, well, you get the point. If it's coming close enough, let's turn it in to something useful.
2. use it as a platform for whatever;
3. sell pieces of it to whomever;
4. mine it for whatever minerals it may carry;
5.
Everything in the Universe sucks: It's the law!
The higher-precision text-based orbital calculator is more accurate. (And overloaded right now.) It has 2002 NT7 in its database. Both claim January 28, 2019 is the date of closest approach. Both claim closest approach around 0.8 AU. Remember, this is projecting many orbits ahead, and small-object orbit projection is inherently noisy because minor disturbing forces matter.
Either we'll know it's a definite miss in a few weeks, or this will be a worry for some time to come.
A Palermo value of 0.06 means that the risk from this object is elevated above the background risk for such objects by about 15%. (The 0.06 is the log of the ratio of the risk to the background risk.) So however worried you were yesterday about collisions with 2 km asteroids, you can be 15% more worried today.
In short, not worth losing sleep over.
http://neo.jpl.nasa.gov/neo/close.html
give distances both in AU and LD (lunar distances) for the dozen or so close passes that happen each month or so.
Not that you should be alarmed.
"It is a greater offense to steal men's labor, than their clothes"
Don't worry about the alarmist graphic. You'll note that they BBC online site uses that "giant asteroid destroying the Earth" image every second on third asteroid story they run. Here's a few recent favorites with the scary image:
Asteroid Impact Centre Site Selected
Earth at Lower Risk of Impact
UK Centre to Study Asteroid Threat
So, yeah, basically you should ignore that image. It's not related to the story in any but the most basic level; it's a picture of an asteroid hitting the Earth... a stock one.
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RumorsDaily
It's because there isn't a global inertial frame of reference.
The rock may be moving quite slowly wrt the place that it departed from, but the sun is moving also, and so is the earth. To expect them to encounter something from "out there" that happens to share their inertial frame of reference... if it did, you wouldn't encounter it. So it will have an inertia more aligned with some other star. Could be quite different from anything local. (It might not, also, but that's not the interesting case.)
I think we've pushed this "anyone can grow up to be president" thing too far.
If you have been following the recent articles about the "Interplanetary Superhighway" discovered by NASA researcher Martin Lo (I have been scouring the net for papers recently) you will realize that there may be a good case for early deflection. In fact NASA re-released the story about this with a little more data just this morning (jpl mailing list). This is hot stuff!
Lo is trying to map the low energy trajectories through the Solar System which result from calculating n-body gravitational problems for all the objects in the System. Apparently there are tube-like trails between the Sun and the Oort Belt along which objects can travel theoretically without thrust, and the dinosaur killer is thought to have come down an "offramp" to the Earth much like Shoemaker-Levy apparently did with Jupiter.
This technology was used in the Genesis Mission and chaos theory applies to the low-energy halo orbit around a Sun-Earth libration point. After orbitting around this point a few times the robot will (without thrust) return to a sample capture point in Earth orbit.
While I do not yet understand the math itself, it seems likely that this Rock is in a somewhat chaotic orbit and that small nudges can have very large effects on its trajectory down the way. A decade or two may not be long enough, or we might even set up a pattern which will smash us on a later orbit, but the technology is being developed right now.