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Naked-Eye Observing - Iridium Flares

These are very peculiar object mostly because they are man-made! A communications satellite "constellation" - that is a group of satellites working together - help transmit a signal around the Earth. The name comes from the initial company - the Iridium Corporation - who planned the satellite cluster to provide global coverage for satellite communications. For more information on the satellites, visit the Iridium website.

I have yet to actually see one. All bets are off in foggy Pacifica!

An iridium flare can look identical to a fireball photographically - which is a very bright meteor. These have also been mistaken for other things like a supernova because of their pulsating appearance.

The brightness of the iridium flare is the result of the Sun reflecting off the surface on the satellite. Sometimes these flares can be visible during the daytime.

Two excellent resources to determine when an Iridium flare (as well as a host of other events) will occur:

  • Heavens-Above - an online ephemeris with a simple interface
  • CalSKY - another online ephemeris with an extensive list of events

You will have to register to get specific data from your location, but the process is benign.

More information can be found here.

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