According to here, the amateur photographer's name is Birg Möbius. The 44 year old wanted to photograph an airplane in front of a rainbow, and suddenly light flashed in the sky.
In the close-up (seen here) the outline of the aircraft ( A Boeing 777) is barely visible. The lightning struck the fuselage and exited out the tail wing.
What happens to a plane when it's struck by lightning?
Most of the time nothing, just like when lightning hits a car. It travels along the outer hull and leaves the plane at a different point (as you can see in the picture).
Sometimes you can find marks of burnt/stained metal at the entry and exit points and the electrical systems may suffer minor damage, but it's totally fine. IIRC, a single airplane gets hit by lightning around once or twice a year.