Complex sentence: On 9 December 2009, "Dmitriy Donskoy" launched a Bulava missile which had a failed third stage and was visible in Norway making a glowing spiral in the sky.
Split into simpler sentences: On 9 December 2009, "Dmitriy Donskoy" launched a Bulava missile. The third stage of the missile failed, and it was visible in Norway making a glowing spiral in the sky.