The world can exhale a collective sigh of relief. A newfound asteroid tagged with the highest warning level ever issued will not strike Earth, scientists said Monday. The giant space rock, named 2004 MN4, was said on Dec. 23 to have an outside shot at hitting the planet on April 13, 2029. The odds climbed as high as 1-in-37, or 2.7 percent, on Monday, Dec. 27. Researchers had flagged the object as one to monitor very carefully. It was the first asteroid to be ranked 4 on the Torino Scale, a Richter-like measure for potentially threatening space rocks. The asteroid...