In this article, the attached image, captioned "The Shenzhou-12 capsule bears the scorch marks from the heat of re-entry," really caught my eye - it looks like they dropped a shipping container from space! I googled the Shenzhou-12 immediately and every other picture seems to show a normal circular spacecraft, so what exactly am I seeing in the image on the BBC?
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2$\begingroup$ I think your eye is simply misguided by the equipment and the flag in the foreground that obscure the round shape. The harsh shadow on the bottom edge doesn't help either. $\endgroup$– asdfexCommented Sep 17, 2021 at 12:58
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1$\begingroup$ @asdfex I mean it's possible? But the corner in the top right seems pretty undeniably square to me $\endgroup$– bendlCommented Sep 17, 2021 at 13:02
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4$\begingroup$ There's no corner there. It's just the edge where the cylindrical black part and the rounded, sand-colored cap meet. It's hard to grasp because of the total lack of a color or brightness gradient in this area due to the uniform illumination. After glancing at the image from some other angles I also was able to convince my brain that it's a box shape... $\endgroup$– asdfexCommented Sep 17, 2021 at 13:05
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$\begingroup$ See also space.stackexchange.com/q/16926/6944 for a similar illusion. $\endgroup$– Organic MarbleCommented Sep 17, 2021 at 13:24
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2$\begingroup$ It's square because... it isn't? You are looking at the side bottom of a near cylinder. The black bit is a curved surface spanning more than 170 degrees of arc. $\endgroup$– CuteKItty_pleaseStopBArkingCommented Sep 17, 2021 at 13:25
2 Answers
As asdfex says, it's an illusion caused by the photo angle and lighting, the cylindrical sides form a sharp angle with the (very much flattened) base.
This photo shows the base of a Shenzhou spacecraft from a slightly different angle.
Image credit: theregister.com
As you can see, the base is convex, not flat, and its circumference has a ring of evenly spaced indentations and raised features:
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compare this to the image you posted...
these marks are widely spaced in the middle but close together at the top and bottom, a typical perspective effect.
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2$\begingroup$ Wow. That's definitely a bit mind bending. What a weird trick of perspective. $\endgroup$– bendlCommented Sep 17, 2021 at 14:58
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1$\begingroup$ @uhoh Me too at first glance! I thing the flag on the left leads the eye to extend the line of the capsule but actually there's a sharp curve from the side to the hatch at the top. $\endgroup$ Commented Sep 18, 2021 at 10:31
Allow me to overlay a side-view diagram of the Shenzhou reentry capsule (borrowed from this wikipedia diagram, and adapted for transparency) on top of your photo:
Now your brain is seeing through the optical illusion: one of the flags is obscuring the curve of the capsule's top, and you can realize that the bottom-left corner is not the capsule itself, but rather an opened hatch or some other piece of equipment.