Coordinate system

What coordinate system does three.js use?
While checking the location of the collision, I noticed something strange.
The y-axis shouldn’t always change, but it keeps changing.
Please check my source.
ask01.html (4.4 KB)

see e.g. Transformations and Coordinate Systems | Discover three.js


Thanks for the attached image.
However, I don’t know why the y-axis value keeps changing. Please see the console log.

For reference, the source will create a cube every time you click on the screen.
It is thought that the resulting cubes should all have the same y-axis.
However, the y-axis is all different.

I found the problem.
I put -90 in the x value to rotate the earth-plane rotation.
However, looking at the manual today, I was instructed to substitute the radian value.
I substitute -0.5*Math.PI for the x value.
The earth-plane rotated exactly, and the value of the collision point caused by mouse clicks was always close to zero.