others saw it too

Ah. Others, further south, spotted the phenomenon.

Caroline sent out this note at 8:52 PM:

Did anyone happen to be looking at Jupiter at around 7.50 this evening?

A friend and I were walking the dogs in York Region Forest, and had been looking at Jupiter. The sky was completely clear, it had just got dark and the only thing visible was Jupiter, which we were seeing in this huge expanse of sky. We had to look to our left and behind us slightly to see Jupiter, which I did every minute or so. I turned to look, and there to the right of Jupiter, slightly lower in the sky was something almost as bright, with a cone of white light behind it. Whatever it was must have been coming straight towards us as it did not move in relation to Jupiter. I did not see when or how it first became visible, but it had not been there a minute before. We saw it for probably ten seconds before it disappeared. It seemed to just fade out really quickly.

Geoff sent an interesting note at 9:44 PM:

This has been quite widely reported across the northeastern United States. It sounds to me like some sort of fuel or water dump by a satellite.

Frank said he thought it the search light from a helicopter. That was a good way to describe the appearance. Except that it wasn't moving, panning, flicking, or vibrating.

Randy, NASA expert, found the answer...

The Charged Aerosol Release Experiment (CARE) was conducted by the Naval Research Laboratory and the Department of Defense Space Test Program using a NASA four-stage Black Brant XII suborbital sounding rocket. Using ground based instruments and the STP/NRL STPSat-1 spacecraft, scientists studied an artificial noctilucent cloud formed by the exhaust particles of the rocket’s fourth stage at about 173 miles altitude.