  The presence of interlayer interactions in twisted bilayer graphene (TBG)
enhances several characteristics, including the optical and electrical
properties. We theoretically investigate the magic angle of TBG according to
the vanishing of Fermi velocity and find double magic angles in a series. The
thermal radiation from TBG can be tuned to the far infrared range by changing
twist angles. The peculiar radiation spectrum is out of atmospheric window,
which can be of great use in invisibility and keeping warm. The total radiation
of TBG is slightly more than twice of a single layer graphene.
