Green Flash

A few nights ago, my sister said she saw a green flash in the sky. I thought it was a meteor. Well, it could not have been St Elmo's Fire. Wikipedia describes the Green Flash as:

"Green flashes and green rays are rare optical phenomena that occur shortly after sunset or before sunrise, when a green spot is visible for a short period of time above the sun, or a green ray shoots up from the sunset point."

Astounding! I would have loved to see it.

Addendum

My sister is certain. It is a meteor. Not the rare Green Flash or Green Ray.