Good morning, Midnight!
Greeting the opposite
"Good morning" to Midnight—she's greeting darkness at the wrong time of day. The reversal signals depression or rejection flipping her world upside down.
Rejected by dawn
"Morn didn't want me—now—" The dash after "now" is classic Dickinson—it marks the moment of realization hitting. Morning itself has done the rejecting.
Permission to witness
"I can look, can't I?" She's asking permission just to watch sunrise. The question mark shows how rejection has made her doubt her right to even observe beauty.
Heart displaced
"Puts the heart abroad"—18th-century usage where "abroad" means displaced or wandering. The hills at sunrise literally send her heart away from her body.
Diminished self
She calls herself "a little Girl" when asking Midnight to take her in. She's making herself small, childlike, helpless—the language of someone whose rejection has shrunk them.