John Bear : Asteroid Apophis flew by this month and was much larger than expected . Named after an evil Egyptian serpent god , Apophis swings by every ten years . The impact caused a brilliant flash , visible in Earth telescopes , and left an ugly dark scar on Jupiter 's cold , gaseous surface . Bear : We can never be 100 % sure how close it will come or if events might change its course . If Apophis hit Earth , he said , the blast would be the equivalent of over a million tons of TNT .
John Bear : Asteroid Apophis flew by this month and was much larger than expected . Named after an evil Egyptian serpent god , Apophis swings by every ten years . Bear : We can never be 100 % sure how close it will come or if events might change its course . If Apophis hit Earth , he said , the blast would be the equivalent of over a million tons of TNT .