Benham's disk is named after the English toymaker Charles Benham, who in 1894 (or 1895) sold a top painted with the pattern shown.
When the disk is spun, arcs of pale color are visible at different places on the disk.
Not everyone sees the same colors.
Color changes by the speed of the disk.

You cannot take a picture of the colors.
If you try to take a picture of the phenomenon, it is not shown on the photo.
That's why the phenomenon is an optic illusion.

The phenomenon is not entirely understood.
One possible reason people see colors may be that the color receptors in the human eye respond at different rates to red, green, and blue.
The arcs of pale color can be seen when disk is spun under homogeneous light.
Try this phenomenon in different environment such as under Sun light, bulb light, fluorescent light, homogeneous light.
And confirm what you can see when the disk spins different direction.

[Precaution]
Please refrain from using when you are not in a good condition of health.
Please stop using immediately if you feel any changes in your health condition (such as feeling sick).