Since 赤 means red, bare, and 道 means way, path?
Actually there are three of these words: 赤道, 黄道, 白道, where '赤' means 'red', '黄' means 'yellow', and '白' means 'white'.
赤道 is the equator. 黄道 is the sun's track in the sky. 白道 is the moon's track in the sky. As for why they are named so - they are named using "the five colors corresponding to five directions", according to 《汉书·天文志》. If you know Chinese, you can refer to this question on 知乎: https://www.zhihu.com/question/21376627
1Exactly, these words are not translated from English but are words which are already there defined by Chinese astrologist thousands years ago. Feb 25, 2016 at 19:19
赤 has several meanings, in this case imaginary or unreal. The equator is a path that has been thought up by the human intellect, and so does not represent a physical boundary per se.
Strange. My Oxford dictionary also gives "loyal, sincere". That's almost the opposite of "imaginary, unreal"... But I know Chinese has such things. Thanks! Feb 23, 2016 at 19:26
Btw, the Coriolis effect implies it's not so imaginary... Feb 23, 2016 at 19:29
Don't think the coriolis effect was known before the equator was defined. Another interpretation is that the red line demarcates a very hot area. Indeed, if you look at a temperature map, you could see a typical red banding around the equator, although it is not the hottest place on earth.– user4452Feb 23, 2016 at 22:19
1Yes, your both points make a lot of sense. Btw, in which dictionary did you find the definition of "imaginary", "unreal"? I don't find it not even here: chineseetymology.org/… Feb 23, 2016 at 22:43
1Can you give a reference why 赤 in this case mean imaginary or unreal ? Feb 23, 2016 at 23:48