What is luminosity? the amount of energy a star emits in a unit of time the brightness of a star as seen from earth the average temperature of a star during its life cycle the degree of shift toward the red end of the spectrum

In astronomy, luminosity is the total amount of energy emitted per unit of time by a star, galaxy, or other astronomical object. So the answer is A.

The amount of energy a star emits in a unit of time

Explanation:

Luminosity of a star is defined as the amount of energy emitted by it per unit time. It is measured in Watts.

The Luminosity of sun is about 3.8 × 10²⁶ W.

Apparent brightness can be measured using the Luminosity. Apparent brightness is the ratio of luminosity per square meter measured at certain distance from a star.

here is the answer

water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering. weathering is the breaking down or dissolving of rocks and minerals on earths surface. once a rock has been broken down, a process called erosion transports the bits of rock and minerals away.