What does the "larger dome" refer to in Today by Billy Collins?
If ever there were a spring day so perfect,
so uplifted by a warm intermittent breeze
that it made you want to throw
open all the windows in the house
and unlatch the door to the canary's cage,
indeed, rip the little door from its jamb,
a day when the cool brick paths
and the garden bursting with peonies
seemed so etched in sunlight
that you felt like taking
a hammer to the glass paperweight
on the living room end table,
releasing the inhabitants
from their snow-covered cottage
so they could walk out,
holding hands and squinting
into this larger dome of blue and white,
well, today is just that kind of day.