The most compelling evidence to date of giant black holes was offered by U.S. scientists in the cover article for this month's Nature magazine. Using a string of radio telescopes, spread from the Caribbean to Hawaii, scientists identified an area of turmoil in space 1 1/2 light years wide -- or 40 million times the size of the Sun. TIME science reporter Michael Lemonick reports that "the very strong assumption is that it has got to be a black hole." He explains that black holes were believed to come in two types: many the size of one star, and others believed to be as large as a million or more stars, which lie in the middle of galaxies. Today's findings seem to show that the second type does exist. Lemonick said, "This is not absolute, iron-clad proof that's it a black hole but it's such strong evidence that nobody doubts it."