Approximate size of the "hut" object observed from the Yutu-2 lunar rover?

Question

News sources (for example, the Independent, the South China Morning Post, RT, and Newsweek) have reported recently on the observation from the Yutu-2 lunar rover of a "hut" object or "funny-shaped rock". Its distance from the rover is said to be 80 metres.

Approximately how large is it?

(image source: https://twitter.com/AJ_FI/status/1466677831929405443)

Idea: Match the image to a portion of a panorama, and scale the width/circumference by the 80 metres radius times 2pi. Good quality Yutu 2 panorama here, but I don't immediately see the match: https://moon.bao.ac.cn/www/plviewer/moon.html (though some of the horizon is missing) — SE - stop firing the good guys, Dec 07 '21 at 17:57
@SE-stopfiringthegoodguys - Thanks for this. I couldn't find a match either, but it may be possible to match these features. Perhaps an image showing the object with the image's overall angle of view marked is also publicly available somewhere. — ool, Dec 07 '21 at 19:07
The interpretation of this silhouette as a cube reflects the human visual bias towards rectilinear objects. If you zoom in and enhance the image, the object's true curvilinear nature will be revealed: a pair of buttocks. — Woody, Dec 07 '21 at 22:32
@Woody another faux rectangles Does the luminous blue shockwave from the RS-25 engine appear to be rectangular? — uhoh, Dec 07 '21 at 23:32
@OhOh For sure. And have a close look at the rock at 8:00 from the buttocks. It is definitely a "Burning Schoolhouse" https://www.archangelfireworks.com/burning-schoolhouse.html — Woody, Dec 08 '21 at 02:21
@KeithMcClary excellent, now need to find the original image to see if it is 4:3 or 1:1 format. What's being shown in the popular press is neither and so probably zoomed & cropped. — uhoh, Jan 08 '22 at 21:11

ool · Answer 1 · 2021-12-08T00:51:13.040

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The width of the "funny-looking rock" is no more than about $6.0$ metres.

The fact that the field of view in the image shown cannot be wider than $360°$ allows us to calculate an approximate maximum possible width. The item takes up approximately $1/84$ of the width of field, so if the width of field represented $360°$ then the item would be about $(2\pi \times 80 \text{ metres}) \ / \ 84 = 6.0$ metres wide.

If the field of view is $360n°$, with $0<n\leqslant1$, then the item's approximate width is $6.0n$ metres. Examples: if the field of view is $60°$, the item's width is about $1.0$ metre; if it is $120°$, about $2.0$ metres.

edited Dec 08 '21 at 00:51

answered Dec 07 '21 at 20:57

ool

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Is the "80" in the calculation the distance to the object, as mentioned in the question? – Organic Marble Dec 07 '21 at 21:00
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Yes - I will edit. – ool Dec 07 '21 at 21:00
Considering that all the rocks in the image have shadows that project towards bottom/left, the angle is way less than 360. more like << 60 degrees, possibly even something like 30. Making the rock about exactly 0.5m wide. – CuteKItty_pleaseStopBArking Dec 09 '21 at 21:26
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on the rover are the Panoramic Camera (PCAM),... the Visible and Near-Infrared Imaging Spectrometer (VNIS) FOV 19.7x14.5 and 6x6 degrees respectively. How big is the bun? – Keith McClary Jan 08 '22 at 20:34

score 3 · Answer 2 · answered Jan 10 '22 at 17:32

The so call hut rock observed by Yutu 2 is apparently another yutu!

'The "mysterious hut" as tall as the Arc de Triomphe turned out to be very small when approached,' they said in the update.

'The drivers were a little disappointed. Just as everyone was lost, a driver stared at the enlarged picture and covered his mouth and exclaimed: "Gosh! This is... Yutu!"'

It's a rock in the shape of a crouching rabbit! ... With rabbit food and droppings to complete the scene.

Approximate size of the "hut" object observed from the Yutu-2 lunar rover?

2 Answers2

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