With reference to Onetrack's comment; Yes, a pretty amazing sight to see. Back in those days I would have blamed it on the dope or acid, but that's just me. While I believe Onetrack I'm the sort of bloke that would say it was something 'of this world' we just don't see that often and therefore have no real explanation. Space is really, really big and if you read Einstein's Special Relativity (a difficult read) you'll understand that travelling at light speed or even a small fraction of that speed is just not possible. If you think time, speed and distance calculations were tricky when learning navigation, try throwing in weird effects like the Lorentz Transform, time dilation and ever increasing mass. (At light speed, mass becomes infinite, go figure...)
It is interesting that the object Onetrack saw was green. That's the color that many Bioluminescent life-forms here on Earth emit. Maybe something to think about.