weather; astronomical phenomena
A somewhat formal or literary term covering both weather and celestial phenomena. In everyday speech, 天気 (weather) or 天体現象 (astronomical phenomena) are more common.
Observe changes in weather and astronomical phenomena.
古来、人々は天象を神の意思と結びつけてきた。
Since ancient times, people have associated celestial phenomena with the will of the gods.
planetarium
From 天 (heaven, sky) and 象 (phenomenon, shape). The exact historical derivation is uncertain; the spelling is conventionally associated with celestial and meteorological phenomena.