orbitals - Why is the energy of an electron always negative?

I just wrote my chemistry exam a few hours ago. However, I am still confused about the following question:

Why is the energy of an electron in an orbital always negative?

I wrote that from the following equation

$$E_n = -R_h\left(1-\frac{1}{n^2}\right),$$

we can see that the energy will always be negative.

Is my answer correct?