How to prevent misalignment of a vertical column when a node label is displayed

Question

I am trying to make a vertical column of various moon phases using a macro that generates circles, but when I add a node label to a circle (to designate that it is a full moon) it shifts the circle that contains the label slightly up and to the right.

\documentclass[leqno,12pt]{article}
\usepackage{tikz}
\usetikzlibrary{calendar,fpu}

\newcommand{\moon}[2][]{%
\def\lunarage{#2}%
\pgfmathsetmacro\textF{ifthenelse(\lunarage==15,"F","")}
\tikz []{
    \draw (0,0) circle [radius=1ex];
    \node[color=black] (0,0) {\textF};
    %
    }%
}
\begin{document}\noindent%
    \foreach \d in {0,1,...,30}{%
    \moon[]{\d}  \\   }
\end{document}

THANKS for any help!

Answer 1

You're drawing a circle and a node over it. As this node is wider than the circle, this particular moon is wider than all other moons.

I think it's better to use a circular node than a circle with a not-drawn node over it. You must be sure that minimum size is big enough to encompass F (or whatever letter you want). This way, all moons have same size.

\documentclass[leqno,12pt]{article}
\usepackage{tikz}
\usetikzlibrary{calendar,fpu}

\newcommand{\moon}[2][]{%
\def\lunarage{#2}%
\pgfmathsetmacro\textF{ifthenelse(\lunarage==15,"F","")}
\tikz []{
    \node[draw, circle, color=black, inner sep=0pt, minimum size=5mm] (0,0) {\textF};
    %
    }%
}
\begin{document}\noindent%
    \foreach \d in {0,1,...,30}{%
    \moon[]{\d}  \\   }
\end{document}