In episode 1 of the TV show, Supergirl, Superman meets Kara when her pod finally reaches Earth.

However Superman was just a baby when they left Krypton, so he would have no memory of Krypton.

I guess they could have left some message in his pod, but Kara was supposed to be the one to protect him so this wouldn't be logical (other than a precautionary measure).

Is there any in-universe explanation of how Superman knew that Kara was is cousin? Or if he didn't know why did he go to her pod when it crashed on Earth?