Nice to meet you!
Use this greeting when you’ve been introduced to a new person by someone you know. For example, if you’re attending an office party and a coworker introduces you to one of his or her friends, “Nice to meet you” would be an appropriate greeting. Only use it when meeting someone for the first time.
Another way is to say, “It’s nice meeting you”.
Do you suppose a martian might say It’s nice meeting you if he came to Earth?