solar power

We are learning to use the clean energy from our dear Sun much better. Although Cosmos 1 wasn't very successful in its mission, it was a big leap forward - if I have the authority to say so.
The new spaceship is going to be our next Sun powered gadget and I have heard that soon enough solar powered planes will be crossing continents. I guess we won't see the white line left after airplanes anymore, is that a sad thing? That was the only way we knew a plane had crossed the sky, right? May be by then they can figure something for that too ...