The strange object was spotted high above Westham last Friday evening by sisters Cheryl Ashwood and Stacey Follan.
They describe seeing a perfectly spherical object, that looked like it was on fire, which moved slowly from Lanehouse towards Portland.
Cheryl, 27, of Dowman Place, said: “It sounds ridiculous but it was a complete sphere of flames – literally like a fireball.
“It rose up to about the height of a light aircraft and moved off towards Portland.
(See previous blog entry Orange lights over Bournemouth usher in a new year)