After a rock hit a Russian town unexpected, i think we still can develop in that field. I would like to have two questions. First, certain sources tell, that even with the help of passively detecting infrared radiation, objects can be detected from very far away in space, and a complete sky browse can be completed in hours. If it is true, then how that meteor wasnt discovered from millions of km-s away? http://en.wikipedia.org/wiki/Chelyabinsk_meteor I gladly post my calculations here or the homework topic, i assumed it was warmed by sunlight to an average lunar temperature, 250K, and a radiating area about 227 m2. I also read, that they underestimated the size of another, low albedo meteor, and they corrected it with the help of a radio-telescope. Can that mean that radars are still superior for observing, detecting things in the solar system?