Final answer:
Crater cracks are detected by visual examination, which is essential for geologists and astronomers to study the age and geological history of a planet or moon's surface. Features like mudcracks provide crucial indicators of the processes that have shaped the terrain over billions of years.
Step-by-step explanation:
Crater cracks are most commonly detected by visual examination. When astronomers and geologists study craters, they often look for distinctive features such as mudcracks. Mudcracks can be significant geologically as they are typically wider at the top and become progressively smaller toward the bottom of the crack, serving as a good way-up indicator when seen in cross-section. This attribute of mudcracks is valuable in determining the orientation of sediment layers on planetary surfaces, which may have formed more than 3 billion years ago, as evidenced by photographs taken by NASA's Mars Rover Curiosity. Additionally, the number of craters can tell us about the relative age of different regions on a planet or moon, with more heavily cratered terrain often being older. This information helps geologists understand how long it has been since the surface was last 'swept clean' by geological processes like lava flows or impacts from celestial events.