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Comment by petermcneeley | Hacker News Reader

Is this video real? That booster seems to be falling very slowly.

It’s an illusion, the larger an object is the slower it seems to be moving. It’s pretty strong if you see a wide body jet or old bomber fly by at low altitude.

As a kid I saw an airliner landing nearby, and I was absolutely certain it had come to a near-stop mid-air. I assumed all of these years that was due to my youth and the fact that I was in a moving car; I didn’t realize this was a known illusion.

When I see a wide body jet fly over my home approaching a landing about 15km away it just looks like it’s impossible how it just hangs there apparently little faster than an airship. Of course it’s actually going 300km/h!

For a commercial airliner on final, probably slower than that, ~240--280 kph (130--150 knots). Given cruise speed is closer to 1,000 kph, that's comparatively quite slow.

Is there a higher quality video where we could estimate its velocity? It seems very slow.

Edit: There is more video here. https://spacenews.com/china-launches-new-beidou-satellites-r...

Max terminal velocity of a skydiver is only 200 km/h.. if this booster is empty this is even maybe slower. Plus real slowness there is also the optical illusion of a very large object in some distance.

So just curious, how fast would you think it should be, and how fast do you think it is in the video?

It makes more sense when you see the wreckage. The entire booster looks like it is made of very thin metal. It is falling on its side just before impact so it has maximum drag at that stage. I would guess it is going 100km/h or less.

This illusion is particularly strong when looking from the moving car. Large low flying planes seem to be standstill in this case.

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