How Do Astronomers Know That the Caloris Basin on Mercury

question 68

Multiple Choice

How do astronomers know that the Caloris Basin on Mercury was formed late in the period of intense bombardment?

• A) Radioactive dating of rock samples has fixed the date of formation.
• B) The basin contains very few craters.
• C) The surface of the basin is much darker than the rest of the planet, suggesting that the surface had not yet been churned over by meteoric impacts.
• D) Mountain ranges in the basin are very high because they have not had time to suffer significant erosion.

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Definitions:

Nerve Net

Of cnidarians and echinoderms, a mesh of interacting neurons with no central control organ.

Neurons

Nerve cells that are the fundamental units of the brain and nervous system, responsible for receiving sensory input from the external world, sending motor commands to our muscles, and transforming and relaying electrical signals at every step in between.

Motor Activity

Bodily movements produced by skeletal muscles that result in energy expenditure, encompassing both deliberate exercise and routine physical activities.

Cerebellum

A part of the brain located at the back of the skull, responsible for coordinating voluntary movements, balance, and posture.