# Problem with figure captions on two different slides

I am having problems with figure captions. Currently, my captions are appearing at the bottom of both two slides. However, I want the captions to appear below the figure on separate slides. Please help, below is my code.

    \begin{frame}
\frametitle{Titan}
\begin{columns}

\column{0.5\textwidth}
\centering

\begin{figure}
\includegraphics<1>[height=4cm]{PIA14445.jpg}
\caption<1>{(Courtesy NASA/JPL-Caltech.)}

\includegraphics<2>[height=4cm]{outgassing.pdf}
\caption<2>{(Tobie et al., 2006)}

\end{figure}

\column{0.5\textwidth}
\begin{block}{Features/Missions}
\begin{itemize}
\item Largest Moon of Saturn
\item Cassini-Huygens mission
\item Presence of Subsurface Ocean + Crust Made of Ice I
\item Atmosphere (Nitrogen/Methane)
\begin{enumerate}
\item Methane needs to be replenished from the interior
\end{enumerate}
\end{itemize}

\end{block}

\end{columns}

\end{frame}

• Welcome to TeX-SE! Please provide us with a complete code that starts with \documentclass and ends with \end{document} and try to avoid including figures that others here do not have, i.e. use something like example-image-a instead. Have you tried using two figures? – user121799 May 10 '19 at 12:14

\documentclass{beamer}
\begin{document}
\begin{frame}[t]
\frametitle{Titan}
\begin{columns}[t]
\begin{column}{0.49\textwidth}
\centering

\only<1>{\begin{figure}
\includegraphics[height=4cm]{example-image-a}
\caption{(Courtesy NASA/JPL-Caltech.)}
\end{figure}}%
\only<2>{\begin{figure}
\includegraphics[height=4cm]{example-image-b}
\caption{(Tobie et al., 2006)}
\end{figure}}
\end{column}%
\begin{column}{0.49\textwidth}
\begin{block}{Features/Missions}
\begin{itemize}
\item Largest Moon of Saturn
\item Cassini-Huygens mission
\item Presence of Subsurface Ocean + Crust Made of Ice I
\item Atmosphere (Nitrogen/Methane)
\begin{enumerate}
\item Methane needs to be replenished from the interior
\end{enumerate}
\end{itemize}

\end{block}
\end{column}%
\end{columns}

\end{frame}
\end{document}