Prince's 1987 double album Sign O' The Times is getting a massive super deluxe edition in September, and here's one of the most sought-after rarities from the collection (and perhaps the entire Prince Vault) -- "Cosmic Day." Recorded on November 15, 1986 and featuring Prince in his pitched-up vocals "Camille" persona, "Cosmic Day" is a helium fueled psych pop treat that really seems like it could've been a hit (for someone, at least), and this nearly six-minute version features some serious shredding, too. Bits of the song have made their way online before but this is the first time the whole song has been shared.

The Prince estate has also shared the handwritten lyrics for "Cosmic Day" as well. Check that out and listen to "Cosmic Day" below.

The Sign O' The Times box set will be out September 25 and features an incredible 63 previously unreleased tracks, 45 of those being studio "vault" tracks like "Cosmic Day."