The dome (or inside shape) of the heavens ascends upwards like a tub, (that is to say) like a tent (denda) which is spread out with its extremities (fixed) || downwards and its dome stretching upwards so that people can sit beneath it and their feet stand on the earth, whilst all of them are inside the tent; in like wise are the heavens, their extremities are (fixed) downwards and their dome stretches upwards and all creatures dwell beneath them as in a tent, as it is said, "And he spreadeth them out as a tent to dwell in" (Isa. 40:22).
The Heavens as a Tent and the Shape of the Dome Above
Pirkei DeRabbi Eliezer 3:10