You can download Celestia from here

---

To download the Black Acropolis for Celestia, click this link and download it into Celestia's Extras folder
The Black Acropolis in Celestia

then follow this CEL link The Black Acropolis

---

To download Blefuscu for Celestia, click this link and download it into Celestia's Extras folder
Blefuscu in Celestia

then follow this CEL link Somewhere near Blefuscu

---

To download Alexandria for Celestia, click this link and download it into Celestia's Extras folder
Alexandria in Celestia

then follow this CEL link Somewhere near Alexandria

---

To download Alfirk Dyson Swarm for Celestia, click this link and download it into Celestia's Extras folder
Alfirk in Celestia

then follow this CEL link Somewhere near Alfirk Dyson Swarm

---

To download Bullseye for Celestia, click this link and download it into Celestia's Extras folder

Bullseye for Celestia

then follow this CEL link Somewhere near Bullseye

---

To download Calyx for Celestia, click this link and download it into Celestia's Extra's folder
Calyx for Celestia
then follow this CEL link Somewhere near Calyx

---

To download Earthland for Celestia, click this link and download it into Celestia's Extras folder
Earthland in Celestia

then follow this CEL link Somewhere near Earthland and its moon Selene

---

To download Ken Ferjik for Celestia, click this link and download it into Celestia's Extra's folder
Ken Ferjik for Celestia
then follow this CEL link Somewhere near Ken Ferjik

---

see also
Orion's Arm Addons in Celestia page One

Orion's Arm Addons in Celestia page Two

Orion's Arm Addons in Celestia page Three