<human>:  Why did they call the first Soviet nuclear test ‘Tsar Bomba’?
<bot>: The bomb was named after the Russian Tsar Nicholas II, who was assassinated in 1918. The Tsar was known for his love of science and technology, and the Soviets were looking to replicate his achievements. The Soviets called the bomb “Tsar Bomba” because it was the largest and most powerful nuclear weapon ever detonated.