陨石即将撞向一颗行星。主角在死前会离开地球多长时间？

At the end of Book 6 of my book series, a magic ritual has caused a large meteorite (around 1/4 the size of the one that caused the chicxulub crater) to ram into the small planet (around the size of Earth's moon). However, the main characters are some time away from their ship when the meteorite hits. If the meteorite hits the opposite side of the planet, how long do these characters have to escape before they are swept away by the shockwave?At the end of Book 6 of my book series, a magic