A Strange Spiral in the Àger sky

On the night of 25 June 2025, my ANNKE NCPT500 surveillance camera, which routinely monitors my telescopes and observatory infrastructure during astrophotography sessions, recorded an unusual and unexpected luminous phenomenon in the sky.

The first image shows a cropped view of the event as seen from my observatory in Àger (Montsec, Lleida). The second image links to a video that documents the complete passage of the object across the (available) field of view.

After consulting several sources, this is what I have found about this phenomenon in the sky:

On the night of 25 June 2025, a luminous spiral cloud was observed across wide regions of Europe, including from my observatory in Àger. The phenomenon sparked widespread curiosity and speculation. Eyewitnesses described a bluish-white spiral slowly expanding in the sky. It remained visible for several minutes and was captured in photographs and videos from multiple locations, including Spain, the UK, France, Italy, Germany, Hungary, and Poland.

Initial confusion led to speculation about meteors or unidentified aerial phenomena (UAPs). However, within a few hours, several weather agencies, space observers, and scientific institutions clarified the origin of the event. The spiral was identified as the result of a fuel venting manoeuvre from a SpaceX Falcon 9 upper stage, following the Transporter-14 mission.

The rocket had been launched two days earlier, on 23 June 2025, from Vandenberg Space Force Base in California. After deploying 70 payloads into sun-synchronous orbit, the Falcon 9’s upper stage conducted a controlled venting of residual fuel before re-entering the atmosphere. This release of liquid oxygen and kerosene in the near vacuum of space crystallised into a visible cloud of ice particles. Sunlight reflecting off this expanding cloud created the spiral effect visible from Earth.

The spiral appeared during astronomical twilight in Europe, when the Sun was just below the horizon. This timing made the ice plume especially visible, as it remained sunlit against the darkened sky. Similar events have occurred following previous SpaceX missions (e.g., Transporter-6 and Transporter-9), and they have become more frequent due to the increased cadence of rideshare launches involving upper stage fuel dumps at high altitude.

Sources consulted:

Space.com – “Spiral spotted in night sky above Europe” (Anthony Wood, 26 June 2025)

Virtual Telescope Project (Italy) – event report and image

Calar Alto Observatory (Spain) – observational data

UK Met Office – official statement on X (Twitter)

Météo-France – clarification via X (Twitter)

Observatory automation and remote operation with Talon6.