Vegas2 last year, the second Friday qualifying session was scheduled for 4:30 as well. It didn't actually get underway until about 4:45. The sun is pretty low in the sky by that time during that time of year so there were still plenty of header flames to be seen. In April, it'll be different as I think the sun doesn't set until after 7:00, as opposed to about 5:45 in late October. It makes sense though what Corey said above here about track conditions.