Complex sentence: This primitive form of astronomy had once been a crucial facet to science and technology in China--so crucial, in fact, that if a Chinese astronomer were to inaccurately predict the occurrence of a comet or eclipse, he would subsequently be ordered to a beheading.
Split into simpler sentences: This primitive form of astronomy was once a crucial facet to science and technology in China. It was once claimed that if a Chinese astronomer were to inaccurately predict the occurrence of a comet or eclipse, he would be ordered to a beheading.