Person 1: Did you hear about the new restaurant on the moon?
Person 2: No, what can you tell me about it?
Person 1: It has great food but no atmosphere!
Explanation: A restaurant is a place to eat. Usually in a restaurant someone asks you what you want to eat and then serves you your food; then you pay for the food. To some people the food is the most important (if not the only) part that matters. To other people, the atmosphere of the restaurant matters. The atmosphere of a restaurant is the way it looks, the way it sounds, the way it smells; it is the way you feel when you are there- much more than just the taste of the food.
The moon, of course, has no atmosphere. When we talk about the atmosphere of the moon we are talking about the layer of gasses that surround a planet or a moon. The moon has no atmosphere; the earth has an atmosphere- that is why we can breathe.
This joke plays with the double meaning of the word atmosphere and that makes it funny! Of course if you want an out of this world restaurant you could try The Restaurant at the End of the Universe.