Stargazers and astrophotographers will soon have to bid #flarewell to the 66 glinting satellites. The briefly-glinting satellites that have become so beloved of stargazers and astrophotographers in the last 20 years will cease to be at the end of 2018.

The 66 mobile satellite communications satellites in low Earth orbit owned by Iridium all have three reflective panels that occasionally catch the Sun and flare for between five and 20 seconds. They can be as bright as magnitude -8, which is brighter than Venus, and over the years have become the target of many astrophotographers and astronomers, keen to see how many they can spot.

As part of the Iridium’s activation of their new Iridium-NEXT constellation, they have been responsibly deorbiting their original Block 1 constellation that produce the flares. Iridium flares are so bright because of the unique design of the Block 1 satellites—the Iridium-NEXT constellation uses an entirely different design, so they won’t be producing flares.

Of the original 95 satellites in the Block 1 constellation, 35 have been deorbited (and one destroyed in a collision), with 25 deorbited in 2018 and 10 since July 1.

In order to predict flares, the satellites must be operational and have their attitudes controlled. Of the remaining 59 satellites still in orbit, 32 have already been deactivated. Another 4 are currently in the process of being deboosted. And 11 are in backup mode, which means they have been moved out of the operational orbits and may not have their attitudes as tightly controlled, also making predictions impossible.

That only leaves 13 fully operational Block 1 Iridium satellites in orbit and those are all expected to be deboosted in the coming months. So, time is running out fast!

If you haven’t ever seen an Iridium flare, you are rapidly running out of time to do so! Star Walk 2 app has got a full list of Iridiums, it also has the Notification setup that will let you know when the next Iridium will fly by so you can spot it.