do you know orange is green inside?

Ok. I have a small orange tree in my back yard. There are dozens of oranges are getting ripe on the tree. So one day, I decided to pluck one of the down to tree it because it looks ripe although a little small.
The texture is a bit different from oranges we get from safeway. They are a little hairy on the surface of the fruit. When I cut the little orange, the most surprising thing is that they are green in color. See! Almost as green as our green placemat!
I can also tell you for sure, they are not ripe yet. Some of you know Pei Sun don't like sour fruits. But guys, an unripe orange tastes much much more sour than lemon does. It is so sour that I can't even eat a single bit of the pulp. Reminds me of those high sour sweets that make your face grin for 10 seconds when first tasted the candy.