Hi,

A colleague at work has described on observation from a few nights ago of what looked like a classic Iridium flare. From his position in Sydney he saw a bright flash then a pale dot moving roughly west to east. That seems fairly unambiguous.

He then went on to say he saw another satellite of similar brightness seconds later going in the opposite direction, roughly west/ south-west, at about the same rate. This "satellite" appeared to change course slightly as if it was raising its altitiude as it crossed the sky.

I didn't think there were any satellites moving in a retrograde orbit. I have no idea what this sighting could have been. I would have guessed a plane if he hadn't said they were about the same brightness. Any suggestions?

Israel launches its satellites in retrograde orbits. It does so because it doesn't want failed launches to fall on its neighbors. The catch, it costs more energy because you lose Earth's rotation instead of gaining it.

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ScienceBits - A random walk in science

Thanks for the info Bugon. They seem to be in fairly highly inclined orbits too which I think makes them a possibility.