Youth has a special place in the hearts and minds of Isaac Asimov fans, simply because it's one of the few short stories by the esteemed author that has alien characters in it. The story was first printed back in '52. Slim is the main character of Youth - he's a little boy whose dad is an astronomer and he's on his way to meet a big-time wealthy man. The man's son recently came across 2 weird-looking creatures, and he persuades Slim to join him and try to create a whole new circus act with these animals.
At the same time, Slim's father, an astronomer, tells the wealthy man that he has seen living-breathing aliens and that they're planning to start interstellar trading. He goes on and says that the aliens' world is dying and needs some help. Their previous civilization was demolished by the nuclear wars, and their world has been decaying ever since. So, that's why they need to do something ASAP, otherwise, their culture might be gone forever.
However, they haven't been in direct contact yet, so, the man and Slim's father decide to go out and look for them. Soon, they come across a tiny crashed ship with a few little dead creatures in it, and the men think that the whole crew died after the crash. But, when Red and Slim tell them that they've got two "creatures" caged up, the astronomer realizes that they are the survivors of the crash!
Next, when they learn that the aliens preferred to be captured and kept against their will when they could just as easily hurt or even kill the two boys, the industrialist (the wealthy man) and Slim's dad put their faith into their civilization and help them to start trading with the human race. The aliens manage to repair their ship and fly back to their own planet.