Planets lose detail when viewed close-up

[88Alex]

I am using Firefox on x64 Linux.
When I first see a planet in Kosmos from a significant distance away, it is very detailed, and looks just like a real planet (although the detail cannot be seen easily in this screenshot):

However, when I approach the planet, it suddenly loses all detail, and becomes an ordinary one-colored sphere:

As seen in these screenshots, the planet loses detail when viewed close-up. This happened with every single planet I ever saw up close.