UPDATE (5 pm ET): Despite the overwhelming similarities between the mystery "missile" and the contrail of a rocket launch, there may be a very simple explanation: It could be an optical illusion.
As detailed by New Scientist, Jonathan McDowell, an astronomer from the Harvard-Smithsonian Center for Astrophysics who tracks space launches, says it was probably an aircraft passing overhead, rather than a vertical rocket launch.
"If it's coming over the horizon, straight at you, then it rises quickly above the horizon," said McDowell. "You can't tell because it's so far away that it's getting closer to you – you'd think it was just going vertically up."
ORIGINAL POST: Monday evening, something launched approximately 35 miles off the Californian coast. A news helicopter even filmed the rocket-like contrail rising like an arced pillar in the sunset. If seeing is believing, there was definitely a rocket launch of some description.
However, no one is claiming responsibility. The U.S. military seems baffled, U.S. airspace was not notified of any commercial satellite launches, no regional Air Force bases had any launches planned and all we're left with are scores of theories as to what it might be.