13
$\begingroup$

The video ESA video Progress launch timelapse seen from space is of course striking for many reasons.

However there is a strange, blinking light structure on Earth that's quite puzzling! I've added a GIF from two screen shots that I've cropped, shifted, zoomed and sharpened to highlight what I'm talking about.

It can't be a reflection from an ISS window because it remains fixed within all the other lights on the Earth. Look after 00:55 in the video, where it flashes at about 2 Hz.

What is it? Where is it?

GIF:

GIF of mystery structure on Earth

According to the YouTube video's notes:

Timelapse of the Russian Progress MS-10 cargo spacecraft launched on 16 November 2018 at 18:14 GMT from Baikonur cosmodrome, Kazakhstan, taken by ESA astronaut Alexander Gerst from the International Space Station.

The spacecraft was launched atop a Soyuz rocket with 2564 kg of cargo and supplies. Flying at 28 800 km/h, 400 km high, the International Space Station requires regular supplies from Earth such as this Progress launch. Spacecraft are launched after the Space Station flies overhead so they catch up with the orbital outpost to dock, in this case two days later on 18 November 2018.

The images were taken from the European-built Cupola module with a camera set to take pictures at regular intervals. The pictures are then played quickly after each other at 8 to 16 times normal speed. The video shows around 15 minutes of the launch at normal speed.

Improve this question
$\endgroup$
4

2 Answers 2

Reset to default
13
$\begingroup$

Update: After quite a lot of searching I believe I've found the culprits!

As suggested in the comments, they appear to be a series of very large power lines around the city of Zalantun in Northwest China. The lines are very difficult to discern from aerial imagery, but I have marked them on this map - if you zoom right in on the red lines you can make out pylons and multiple parallel cables. Also marked is an airport between the power lines which explains why they are lit at night.

enter image description here

The three large, lit metropolitan areas seen at around 1:03 in the video are the cities of Qiqihar, Daqing and Harbin (from farthest to closest).

ISS Tracker confirms the station was passing just North of this area at between around 1827-1829GMT November 16th - around 13-15 minutes after launch from Baikonur, coinciding with when the cities are visible on the left (to the South) in this image from the footage:

enter image description here

The footage is taken from the East and from a very low angle, making the perspective a bit mind-bending, but explaining the exaggerated curvature of the Southernmost power line. As far as I can tell, the lines are (as of the aerial images being taken) still under construction as in may places only the pylons are visible.

Improve this answer
$\endgroup$
3
  • $\begingroup$ This sounds really promising, thank you! Here's one example of NASA "black marble" images earthobservatory.nasa.gov/features/NightLights/page3.php There are probably other ways to get this kind of thing as well, e.g. viirsland.gsfc.nasa.gov/Products/NASA/BlackMarble.html $\endgroup$
    – uhoh
    Commented Nov 24, 2018 at 15:28
  • 1
    $\begingroup$ @uhoh yeh that'll certainly help a lot! I'll come back later and have another go at tracking them down, but feel free to edit if you find them in the meantime! $\endgroup$
    – Jack
    Commented Nov 24, 2018 at 15:42
  • 3
    $\begingroup$ I agree with your position estimate. I found several quite large power lines in the area, like this one: openstreetmap.org/way/308666877 I'm pretty confident it's collision avoidance lights on some of the towers of such a line. $\endgroup$
    – asdfex
    Commented Nov 24, 2018 at 15:51
1
$\begingroup$

I was asking myself the same question. My guess is: it could be a street illuminated with LED street lights, and the flicker is an artefact caused by the 50 Hz A/C mains current to power the LEDs and the timing of the camera shutter.

Improve this answer
$\endgroup$
6
  • $\begingroup$ btw I used to think LEDs were driven with a pulsed waveform at higher frequency than that for efficiency, but many answer agreed that LEDs streetlight these days were DC. Are LEDs in modern streetlights usually pulsed? If so, roughly what frequency? When many LEDs are in series, there is a high frequency involved to make a higher DC voltage in some cases. $\endgroup$
    – uhoh
    Commented Nov 24, 2018 at 11:17
  • 1
    $\begingroup$ That's not possible. If you had a light switching on and off at 50 Hz you couldn't use that road without a huge stroboscopic effect. The effect would be like single images every ~30cm at 100 km/h. $\endgroup$
    – asdfex
    Commented Nov 24, 2018 at 15:06
  • 1
    $\begingroup$ @asdfex The Mercury and Sodium lights are probably flickering at 100 or 120 Hz and it's not very noticeable. I don't think LEDs would be built to blink, but if they did at 100 or 120 Hz we might not know. $\endgroup$
    – uhoh
    Commented Nov 24, 2018 at 15:18
  • 2
    $\begingroup$ @uhoh: These never switch off completely - they just get dimmer a bit. And I can tell you, the ~ 1kHz of modern LED backlights of cars are already very annoying to my eyes. $\endgroup$
    – asdfex
    Commented Nov 24, 2018 at 15:25
  • 2
    $\begingroup$ this is timelapse, showing stars and the night side of the earth, so the exposure time is probably longer than normal. under such conditions no 50 hz (or similar) flicker can be registered. $\endgroup$
    – szulat
    Commented Nov 25, 2018 at 1:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.