2029: Asteroid MN4 to pass closer than geostationary satellites - visible

Anxious Earthlings need not worry too much for another 24 years, however, because asteroid 2004 MN4 is not due to make its closest approach to Earth until about 10pm London time on Friday 13 April 2029.

The latest calculations of the rock's orbit suggest that it will come so close that it will probably be visible to the naked eye from Britain. It will shine in the sky as a dim, fast-moving star - the first asteroid in modern times to be clearly visible from Earth without the aid of a telescope or binoculars.
...
The latest revisions of the calculations have refined the asteroid's orbital path to suggest that it will pass our planet by the relative whisper of 36,000km (22,600 miles) - well within the orbit of geostationary satellites and about a tenth of the distance to the Moon. This is by far the largest of the top 10 closest asteroids recorded by astronomers. Only two others have come closer and both were much smaller objects - tens of yards wide instead of the 350 yards of asteroid 2004 MN4.

Professor Mark Bailey, director of the Armagh Observatory, said that there was little danger from the asteroid even though it would come close enough for its orbit to be directly affected by the Earth's gravity - causing the path of the space rock to swing away.

http://news.independent.co.uk/world/science_technology/story.jsp?story=611219

Between January 27 and 30, a team led by Lance Benner of the Jet Propulsion Laboratory in Pasadena, California, tracked the asteroid using the enormous Arecibo radio telescope in Puerto Rico. By bouncing radio waves off the asteroid, the astronomers received precise information about its position and speed that enabled them to plot the object's course over the next 24 years with great accuracy.
...
But there's another reason for concern. According to Dan Durda, another SWRI astronomer, 2004 MN4 is likely to be a "rubble-pile" asteroid, consisting of material only loosely held together by gravity. Because the asteroid will pass us at just 2.5 times Earth's diameter, tidal forces could tear it apart. The result would be a trail of rocks drifting slowly apart with the passage of time. One or more of these might hit Earth in the more distant future, creating a spectacular fireball as it burns up in the atmosphere.
...
So, take note: On Friday, April 13, 2029, from dark-sky sites throughout Europe, 2004 MN4 will look like a 3rd-magnitude star. It will be moving a quarter of the way across the sky in just an hour, its motion among the stars clearly evident.

And maybe, just maybe, you'll see an asteroid die.

http://www.astronomy.com/default.aspx?c=a&id=2874