Reddit user p0nette posted this image to Imgur and Reddit with the question “Saw this tonight in Reunion Island, what is it ??!”

Here’s a full-size crop of the cloud:



If your geography is as rusty as mine was, Réunion is a French island in the Indian ocean off the east coast of Madagascar. I wondered if the image might be related to today’s Falcon 9 launch.

When an upper stage doesn’t work correctly in space, it often leaves an interesting display. The unburned propellant creates a cloud in space that can reflect sunlight and be visible over a huge area. A previous SpaceX launch caused reports of a UFO over Australia.

Could p0nette’s object be the upper stage of the Falcon 9 that was launched this morning? I think it is.

In the press conference after the launch, Elon Musk said that SpaceX attempted a relight of upper stage but encountered an anomaly. So it certainly could have left a cloud of propellant floating in space.

One of the missions on the Falcon 9 was DANDE, the Drag and Atmospheric Neutral Density Explorer, designed and built here in Colorado. They posted “Two Line Elements” to their website after the launch, which give the orbital information of the satellite. While the satellite and upper stage will drift apart over time, early in their orbits they should be fairly close together.

With the orbit data we can rewind time using Alexandru Csete’s software Gpredict and find the course that DANDE, and the upper stage, flew over. The rocket launched at 16:00 UTC, here it is just after launch at 16:09 UTC:



Here it is an hour and a minute after launch, after it flew south over Antarctica and then north up the other side of the world:



The yellow circle represents the area over which it could be seen above the horizon. From Réunion, it would have been almost directly overhead, and would have taken some time to cross the sky. Réunion’s time zone is UTC+4, so it would have been 9:01 PM local time when it was highest in the sky.

I haven’t yet gotten confirmation from the original poster as to when it passed and what direction it was traveling, but this seems like the most likely candidate for the source of the cloud. I’ll update further when I find out more.

If you’ve seen more images of the cloud or have questions, please contact me at wikkit@gmail.com.