此当是乾元二年七月在秦州作，故有"伴月落边城”之句。王柏曰：天河，从北极分为两头，至于南极，随天而转入地下过，水之气也。《广雅》：云汉、星汉、河汉、银河、绛河、天津、汉津，皆天河名。
杜甫·《天河》
常时任显晦，秋至辄分明。
纵被微云掩，终能永夜清。
含星动双阙，伴月照边城。
牛女年年渡，何曾风浪生。
The River of Heaven
Du Fu
The moon forever turns obscure or bright,
But clearest in the autumn, though sometimes
A floating cloud may darken it a while,
Keeps purely shining through the endless night.
The stars that move through the gates of night and day
Companion the moon down frontier walls:
The Spinning Girl1 and the Cowboy year by year
Have met nor wind nor wave upon the Milky Way.
1. The star Vega in the constellation of Lyra.
2. Herd-boy, stars in Aquila. The union of their constellations occurs on the 7th of the 7th lunar month.
