From at least the time of Sima Qian 司馬遷 (c.145–c.86 BCE), Chinese sources consistently divided the astral sciences into tianwen 天文 ‘heavenly patterns’ and li 曆 ‘calculation’. In short, the former is devoted to interpreting ‘anomalies’ (yi 異), the latter to modelling ‘regularities’ (chang 常), and though no one in his day could predict them with any accuracy, Astronomer Royal Sima Qian makes a forceful argument that solar eclipses are nevertheless perfectly ‘regular’ and, thus, not to be read as omens (zhan 占). Seven centuries later, when experts were able to calculate their exact time, place, ‘starting corner’ and magnitude with relative ease, we then hear Astronomer Royal Li Chunfeng 李淳風 (602–670) argue the opposite: that, regardless the protestations of sceptics, eclipses are nevertheless ‘catastrophes’ (zai 災) linked to political dysfunction. In this talk I will discuss Li Chunfeng's curious position, presented in the omen compendium Yisi zhan 乙巳占, then turn to his other works and activities in tianwen omenology to explore how he may have put theory into practice. With an idea of what he personally did about solar eclipses, I will then take a broader look at the practice of their interpretation to his day to hypothesise about what was at stake in declassifying them as ‘anomalies’.