Equation tag not showing

Question

Sorry, real noob here... I just need to typeset the following equation. I found a way to split the too long equation into two lines, but now it does not typeset/give equation tag: why?

\begin{equation*}
    \begin{aligned}
    W [ & \text{inverse distance attraction} \\
    & \mid \text {elliptic orbits and the "second law"}] \approx 1 \label{a3}
    \end{aligned}
\end{equation*}

I am using TeXShop on Mac Os X.

Answer 1

The equation* environment is untagged. Drop the asterisk and use equation instead.

Answer 2

I guess that you only need to remove the asterisk in the begin and end equation:

\begin{equation}
    \begin{aligned}
    W [ & \text{inverse distance attraction} \\
    & \mid \text {elliptic orbits and the ``second law''}] \approx 1 \label{a3}
    \end{aligned}
\end{equation}

Also, don't use the character ", called dumb double-quote marks, for typestting; use `` to open the quote and '' to close.