The ArcGIS Explorer default map, and maps and layers you can discover on the Explorer Resource Center, are created using ArcGIS Online services. Behind the scenes these have been authored using ArcGIS Desktop, and are powered by ArcGIS Server.

We've chosen a subset of all of the available ArcGIS Online services to include on the Explorer Resource Center, but you can connect directly to ArcGIS Online and shop around for more. Here's how...

Go to File > Open, and choose Servers. You'll see a list of the available connections you can make across the top. Choose ArcGIS Server (since the ArcGIS Online services are ArcGIS Server based) and type the following connection URL:

http://services.arcgisonline.com/arcgis/services

You'll see a list of all of the available services, many of them organized into folders.

At the bottom left of Open Content you'll see a link to the Help on Opening Content that includes a legend describing the icons you'll see:

Since Explorer is a globe, the globe services will be optimal. Many of the listed services are intended for use in ArcGIS Desktop, but any services you find will work just fine.

In this example, let's click to open the NASA CloudCover_World, and choose Space:

We've just added a cloud cover layer to our map. There lots of content to choose from, so try browsing for others you may find of interest.