Plate XLVIII — Exchange Rate (the Ledger Nebula)

Observing note

Under a narrowband filter this nebula resolves into parallel dark columns, and the house engraver could not resist drawing them as a ledger. The red emission on the left he called the debits; the fainter blue reflection on the right, the credits, and the balance never quite closes. A northern winter object that rewards a long, slow exposure and a willingness to be owed.