What does "Leaning under the Starry Sky" express?

Expressed the loneliness and desolation of the poet's heart.

"The stars come down from the clearing and the moon comes up from the river" is a poem in Du Fu's One Night in a Foreign Country. This poem expresses Du Fu's lonely and desolate mood during his journey. "Stars Down from the Open Space" vividly depicts the starry sky hanging over the vast Yuan Ye, while "Moon Running Up the River" depicts the magnificent scene of the surging river. These two poems indirectly express the loneliness and desolation of the poet's heart through the description of the scenery.