Rocket Twilight Phenomenon

When a rocket launches just after sunset it rises into the air and, if the timing is right, part of the rocket exhaust will enter the light from the sun and leave a colorful trail behind as the exhaust freezes and ice crystals form. This is called the “twilight phenomenon” and is fairly rare as the timing of the rocket launch window and sunset have to coincide just right.

This happened on 22 September 2005 and my trip to see it was very short: I walked out of my front door and set up the tripod and camera in the driveway. 🙂

[Photos on this page can be enlarged by clicking on them. Click outside the photo to close the box it displays in.]

Twilight 01 Rocket Taking OffFirst, the rocket rises in the dark part of the sky; in this case over the house across the street…

Twilight 02 Rocket Entering SunlightThe missile in this case was a hybrid rocket called a Minotaur. The first stage you see here was a retired Minuteman missile; sitting atop it are Pegasus rocket parts carrying a classified payload.

As the rocket rises, the first stage burns out and the second stage ignites. The brightest picture here is the moment when the second stage ignited. The rocket then continues on its southern course but because the Pegasus exhaust differs from the Minuteman exhaust, the second stage does not leave the same ice crystals in the atmosphere and so contributes less to the formation of the twilight phenomenon…

Twilight 03 Second Stage Firing Twilight 04 Second Stage Departing Twilight 05 Second Stage Well on the Way

Finally, after the rocket has gone out of sight, the exhaust remaining forms a multi-colored cloud in the sunlit portion of the sky. And, as the sun sets, this cloud gradually loses its color and disappears into the night…

Twilight 06 First Stage Trail SpreadingAnd, then, the show is over. All in all, about 15 minutes from start to finish.

Twilight 07 Show Almost Over

[This page was moved from my site to TomsFotos 18 Jan 2015.]