Friday 12 June 2015

Dazzled by an Iridium Flare

I was having my usual late night potter around at midnight last night, taking a gentle late night tour of the sky.

I've been neglecting my astronomy I know, I keep saying! There just aren't enough hours in the day or night to do everything, and I have to rest occasionally. Using binoculars makes my eyes tire very quickly at night these days. But luckily, the sky has more than enough to keep the naked eye interested.

So it proved last night. Approaching low from the south, rising up to meet the bright orange star Arcturus, was a faint satellite. I could see however that it was brightening up, so I figured out quickly what it was.

The Iridium Satellites

These are communications spacecraft who's highly reflective panels direct sunlight onto a narrow strip of the Earth below as the satellite passes about 900km up. I've seen them before, the brightest ones reaching about the same brightness as Venus, around -4 for a few seconds before the sun-satellite angle becomes unfavourable for the observer and the Iridium craft fades away again.

This one, however, became almost as bright as a half moon. It cast shadows, had a halo lighting up a quarter of the sky, and it all but hurt my eyes to look at.  It drowned out the stars for a moment, and it almost felt like a celestial god was shining a torch on my face, it was dazzling.

Outside of the moon, this was the brightest object I've ever seen in the night sky.

A twitter contact down south thought it might have been a flash of lightning.

It was actually Iridium 32, and it had reached a magnitude of a shade under -8.

You can use the "Heavens Above" website to predict views for Iridium Flares - and also things like International Space Station passes. This is the pass I observed last night. If you enter your location, it will predict and locate bright Iridium Flares for you.

They really are spectacular.


All text copyright CreamCrackeredNature 12.06.15


  1. I love watching the ISS pass over so will check out the Iridium Satellites too :) Thanks for the useful information Simon.

  2. Not a problem, a very different challenge to the ISS, but a spectacular one on occasion.

  3. We try to watch the ISS when it goes over, and my son - who is a radio ham - can actually hear them on his radio.

  4. That is interesting, wonder sort of mundane chats they have as they sail above the Earth.

  5. More about Iridium flares in this excellent blog post!