Because the moon's body blocks direct radio communication with a probe, China first had to put a satellite in orbit above the moon in a spot where it could send signals to the spacecraft and to Earth.

How humiliating: you tried to send a direct message to a member of your Twitter coterie but couldn't because they quit following your tweets.

You can create links to particular users in messages by entering @ followed by their user name or send private 'direct messages' through the system by typing d and the user name.