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

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?

– ool
Dec 7, 2021 at 17:44
• @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 7, 2021 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. Dec 7, 2021 at 22:32
• We are being "Mooned" Dec 7, 2021 at 22:49
• @uhoh I found the FOVs, see below. Jan 8, 2022 at 20:57

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 $$0, then the item's approximate width is $$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.

• Is the "80" in the calculation the distance to the object, as mentioned in the question? Dec 7, 2021 at 21:00
• Yes - I will edit.
– ool
Dec 7, 2021 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. Dec 9, 2021 at 21:26
• 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? Jan 8, 2022 at 20:34

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.