What is an Iridium Flare?

I'm sure at some time or another you have seen a satellite transit the sky above your head.  However, what would happen if the satellite was angled just right such that it reflected the Sun back down to you.  This is what is known as a satellite flare.  The satellite will brighten significantly, potentially becoming brighter than a crescent moon.

There is a group of satellites (called a constellation) that are controlled and have easily predicted satellite flares.  These satellites are the Iridium Satellites.  The original plan was to have 77 of them in orbit (77 is the atomic number for Iridium) but only 66 were necessary to be operational.

The following site is a good resource for locating iridium flares from your location.

http://www.heavens-above.com/IridiumFlares.aspx

You can also download the Heavens Above application for your mobile device that will provide you with all the information necessary to see a flare and other controlled satellites; even the space station.

Iridium flares typically occur several times an evening and they are VERY easy to see.  Using the app, find the place in the sky where it will occur and start watching a minute before it is due to flare.  You should see a dim satellite nearing the flare point all of a sudden become the brightest object in the sky.  You may think it is a plane, but it can be even brighter.  An image of a flare is shown below.

Iridium Flare

On Wednesday March 15, 2017 at 9:02pm in Calgary there will be a very bright flare between the heads of Gemini and the head of the lion of Leo.  See the map below for details.  If you miss it don't worry as these are a common occurrence.

-8.4 Iridium Flare, Calgary, AB March 15, 2017, 21:02

However, in the near future these satellites will be going offline and replaced by a newer fleet.  A news article on this is provided below.

http://news.nationalgeographic.com/2017/01/skywatching-iridium-flares-spacex-satellites-space-science/

I would suggest grabbing the Heavens Above application and go outside to catch one of these before they become extinct.  If you can photograph one that would be amazing.  I will try for the bright one tomorrow by placing a wide-angle between the two heads and start a long exposure.  Good luck if you attempt to see it!