If you mean how far. If you can see the stars in the Milky Way - that is about how far we can see.
Human eye cannot estimate speed because planes are too fast for an eye to estimate speed.
microeconomist
A microbiologist.
A microbiologist.
No, for most people that is too cold.
A stethoscope
A microbiologist.
Do examine objects with detail too small to see with the human eye.
I looked it up in my physics text book and it says that the wavelength is too long to be seen by the human eye.
A microscope.
It's either microeconomist or microbiologist.
Any organism which is too small to be seen with the unaided human eye is by definition a microorganism.