Why are comets visible only when they are near the sun?

Nasa scientists must work together to make sure that everything is correct and accounted for when launching a shuttle. besides a physicist, what other type of scientist would be in making sure that the shuttle has the appropriate type and amount of fuel to reach its destination?

What maintain homeostasis when a persons internal body temperature is 97.5°f

Which of these statements is false? a. others may notice a problem with a relationship before the people involved. b. the first sign of a problem with a relationship is a feeling of anger. c. damaged relationships can be repaired. d. even good relationships can be damaged.