![](https://mcdonaldobservatory.org/sites/default/files/images/news/gallery/kepler-18-graphic.jpg)
Caption:
The top graphic shows the orbits of the three known planets orbiting Kepler-18 as compared to Mercury's orbit around the Sun. The bottom graphic shows the relative sizes of the Kepler-18 and its known planets to the Sun and Earth. Credit: Tim Jones/McDonald Obs./UT-Austin