The Size of the First Contact Borg Sphere

During the battle of Sector 001 the Borg launched a Sphere in order to travel back to the year 2063. The USS Enterprise-E destroyed the Sphere. The remains of this Sphere ended up in the Arctic Circle.
From ENT: "Regeneration" we know that the scientists calculated a diameter of about 600 m. This contradicts the concept designs of John Eaves. Borg Sphere: 1300 feet (= 396 m).

design scetch by John Eaves (johneaves.files.wordpress.com)

How was the size of the Sphere now implemented in the studio model?

For the calculation of the size I use a photo of the Borg cube at the Children's Museum of Indianapolis Star Trek exhibition.

Borg cube miniature used in 1996 film "Star Trek: First Contact"
Robert Scheer/IndyStar

From John Eaves design sketch we know that the edge length of the Borg cube is 9000 feet (= 2743 m).

• Because the photo doesn't show exactly the front of the side with the opening for the Sphere, I transferred the edge length to the middle of this opening.
• If you now set the height of the opening in relation to the edge length, you get a diameter of 503m.
• The red circle shows the size of the Borg Sphere with 396 m diameter (as on the design sketch of John Eaves).

The space between the sphere and the opening also corresponds to the perception in the film.

screenshot by trekcore.com (Star Trek First Contact)

I've added that to my Size Chart for the huge ships.