Bay of Rainbow in Hong Kong

orion

今天的 Lunar Photo of the Day ( http://www.lpod.org)刊登了一幅有趣的香港地貌和月球地貌之比較圖片,見下圖

oldfield

Nice!  I'm interested to know their relative size, my very 粗淺 understandings told me that size does matter on the formation of features like this.

mca

Interesting! Thanks for sharing. The following discussion is just for fun.

Suppose you stand on one end (cape) of the HK “Bay of Rainbow”. You are definitely able to see the opposite cape.

Now imagine you stand on the peak of one cape of the Bay of Rainbow (Sinus Iridum虹灣). You will see nothing about the opposite cape, because the bay is large (230 km cape to cape) and the relatively sharp curvature of the global Moon blocks the distant view. See illustration below or from



Alan Chu
2008.01.10

P.S.  In p.28 of HKAS Newsletter (2007 Dec issue) , 向問天 gives a similar discussion on horizon distances.

mca

Please note that the lunar photo of Sinus Iridum is south up, so Cape "East" is on your left hand side while Cape "West" is on the right. Both capes have offical names, too long to mention here.

By experience, the Moon always shows more "funny" stuff in visibilty, if you let the lunar image south-up. Using a star diagonal will produce an awkward (mirror reverse) visual view not compatible with most Moon atlas.

AC