Satellites that Flash or reflect sunlight?

[Orionskies]

Being new to astronomy I've recently started observing the night sky and all its natural wonders But there are lots of man made wonders as well in the form of satellites moving across the night sky. But the other morning around 4am I saw what appeared to be a satellite moving across the sky except it flashed a brilliant white light intermediately.

Does anyone know if satellites are observed to do this?

[Kunama]

Tumbling Iridium satellites reflect Sunlight as they tumble. Look at the Heavens Above website for timings of visible satellites.

[Allan_L]

Yes.
Satellites "shine" by reflecting sunlight from shiny surfaces towards Earth.
Some (non-functional) satellites and objects, such as burnt out rocket bodies, can appear to flash intermittently, because they may be tumbling end over end.
On the other hand some satellites will give a single brilliant flash when a solar panel or antenna aligns with the Sun; Iridium flares are an example of this and their "flash" can be predicted precisely using various apps.

[MichaelSW]

Julian,

Some satellites rotate for stabilisation purposes. Variations in their surface / projections will cause a variation in reflectivity, hence the flashing. Some satellites or other bits of space junk may be tumbling in orbit (out of control!)

This article gives a good explanation.

http://www.satobs.org/tumble/tumbleintro.html

Cheers.

[Orionskies]

Thanks all for clarifying this for me and for the extra resources. :)

[madwayne]

Here's a post one such "flasher", known as the Virgo Flasher.

http://www.iceinspace.com.au/forum/showthread.php?t=139281

Wayne

[Orionskies]

Thanks Wayne.

I didn't realize there could be such a following for satellites and the one I saw did have a very bright flash that made it stand out.