spaceplasma:

Twilight phenomena

Twilight phenomenon is produced when unburned particles of missile or rocket propellant and water left in the vapor trail of a launch vehicle condenses, freezes and then expands in the less dense upper atmosphere. The exhaust plume, which is suspended against a dark sky is then illuminated by reflective high altitude sunlight, which produces a spectacular, colorful effect when seen at ground level. The phenomenon typically occurs with launches that take place either 30 to 60 minutes before sunrise or after sunset when a booster rocket or missile rises out of the darkness and into a sunlit area, relative to an observer’s perspective on the ground.

This phenomenon usually produces a cloud of green, blue, white and rose colored hues which takes on a corkscrew appearance as it is whipped around by wind currents. It is seen within two to three minutes after a launch has occurred. Depending on weather conditions, it could remain in the sky for up to half an hour before dispersing.

Pre-dawn launches are probably less spectacular than their dusk counterparts. During dusk launches, the sunlight shines through the exhaust plume. Pre-dawn launches, on the other hand, produce a more subtle display because the sunlight directly reflects off the plume.

Living in southern California, I’ve seen these several times after a Vandenburg launch. I remember one in particular when I was living in Redondo Beach in the apartment on Carnegie Lane, which would have made it 1986 or so. Or maybe it was later, when we were renting the house with bad plumbing on Lynngrove Dr.; that would have been 1994-ish. Weird that I can’t remember which it was. But it was one or the other.

I remember the moment itself clearly. We had ordered takeout from a Mexican restaurant on Highland Avenue, down near the beach, and I’d driven down and found parking a block or so away. I was walking north on the east side of Highland toward the restaurant. The sky was clear, with that warm, half-hour-after-sunset glow.

As I admired the view I saw what looked like a bright star or planet low in the west. It was like Venus, except I knew Venus wasn’t there. It rose, slowly at first and then faster, and as it rose it brightened, and the brighter it got the more trouble I had convincing myself it was a helicopter or an aircraft with its landing lights on.

Then staging happened. The bright dot bloomed into a big, translucent bubble, and as the central dot reappeared and continued crawling upward I could see the contrail, and I finally knew what it was. I watched as the rocket winked out at the end of its burn, then watched the backlit contrail twist in the high-altitude wind until it looked just like those images above.

I wanted to share the moment. I looked at the people passing by, but no one made eye contact. No one followed my gaze. They just stepped around me and kept walking, heads down.

Reposted from http://lies.tumblr.com/post/62561644213.