Friday the 13th, 2029? The odds of impact

  • Thread starter Ivan Seeking
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In summary, Check is citing odds that are even worse now! Asteroid 2004 MN4's chance of impacting Earth on April 13, 2029 has increased from 1 in 300 to 1 in 37. It's still a very small chance, but it's worth being aware of.
  • #36
Orbital velocity of 2004 MN4

Period of revolution about sun, P = 0.8853 y
Distance from sun at Perihelion, q = 0.7457 AU
Distance from sun at Aphelion, Q = 1.0982 AU
Inclination wrt Ecliptic, i = 3.3334 deg

So it crosses Earth's orbit twice, and the orbit of Venus twice during one of it periods. See my previous post in this thread with a link to the NASA site that shows the orbit of 2004 MN4. (Note - there is no orbital precession, so the simulator is not entirely accurate).

As it nears the Earth's orbit, the velocities are very close, probably on the order of 1 km/s (3600 km/h or 2200 mph) apart. Outside of Earth's orbit, the 2004 MN4 is traveling slightly slower, and as it nears the orbit of Venus, its speed is a little faster than Venus. But what counts is the velocity in the vicinity of the Earth. If it got near enough to the Earth, the Earth's gravity would accelerate it.

The mean Earth orbital velocity is approx. 29.786 km/s (107,229 km/h).

To capture it one would have to decrease the orbital velocity to less than escape velocity from earth, which is about 11.1 km/s (40,200 km/h, or 25,000 mph). Compare this to the moon's orbital velocity of 1.023 km/s.

If anyone wants to worry about something, take a look at all the other NEO's - http://neo.jpl.nasa.gov/orbits/
 
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  • #37
I think if we get hit, it'll be by one we didn't see coming. How long has this asteroid been orbiting the sun? 1000s of years, typically crossing our orbit twice a year?
 

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