Google Maps too. To view the moon and Mars in Google Maps switch the base map to Earth view then zoom out as far as possible. The options for moon and Mars appear when you have completely zoomed out.
There are labels on the moon and Mars views in Google Maps. You can click the labels to learn a bit more about the highlighted locations. Unfortunately, you cannot create tours or placemarks on the the moon and Mars views in Google Maps in the same manner that you can in Google Earth.
Applications for Education
As mentioned above, the option to explore the moon and Mars has long been available in Google Earth. Being able to do the same in Google Maps presents the same opportunity to students who don't have Google Earth installed on their computers. In particular I am thinking about Chromebook users who aren't able to install Google Earth. The only shortcoming of the moon and Mars views in Google Maps compared to Google Earth is that you cannot measure or add placemarks.
H/T to Google Maps Mania.