What according to romeo would juliet's eyes cause to happen ?

Romeo compares Juliet's eyes with the stars. He believed that her eyes were speaking to the stars, and that the stars were speaking to them. Romeo seems to have believed that the stars had left their places and wanted Juliet's eyes to twinkle while they were gone. In comparison to the stars, Romeo questions himself about what would happen if the trade was made, and he comes to the conclusion that the brightness of her cheek would outshine the stars as well.