This August, 2018, article raises this question for those who believe the Bible, in which it is written that God said that He made the firmament (rakia) on the second day of Creation.  The article reports that the New Horizons spacecraft discovered what looks like a brightly shining wall on the edge of space.  Is this the boundary of the visible heavens? 

https://gizmodo.com/new-horizons-spacecraft-sees-hydrogen-wall-at-the-end-o-1828258683 

Gen 1:6-8 Then God said, “Let there be a [a]firmament in the midst of the waters, and let it divide the waters from the waters.”  Thus God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament; and it was so.   And God called the firmament Heaven. So the evening and the morning were the second day.