Question

____ and the tilt of earths axis are two significant factors related to the suns uneven heating of earth.

Explanation:

The significant factors related to the sun's uneven heating of Earth, along with the tilt of Earth's axis, include the Earth's spherical shape (or curvature). The Earth is a sphere, so different latitudes receive different amounts of solar radiation. Areas near the equator get more direct sunlight, while areas near the poles get more spread - out (and thus less intense) sunlight. This, combined with the tilt of the axis (which causes seasons), leads to uneven heating. Another common factor is the Earth's rotation (but more precisely, the spherical shape is a key factor for the uneven heating due to the angle of sunlight incidence). However, the most appropriate factor here, considering the context of the sun's uneven heating related to the shape and tilt, is the Earth's spherical shape (or curvature). But also, the Earth's rotation is not the main one here. Wait, actually, the two main factors related to the sun's uneven heating of Earth are the Earth's spherical shape (causing different angles of sunlight incidence at different latitudes) and the tilt of Earth's axis (causing seasonal variations in heating). So the blank should be filled with "Earth's spherical shape" (or "Earth's curvature" or "Earth's shape"). Alternatively, another factor is the Earth's orbit? No, the main ones are the spherical shape (distribution of sunlight due to curvature) and the axial tilt. So the correct term to fill in the blank is "Earth's spherical shape" (or "Earth's curvature").

Answer:

Earth's spherical shape (or Earth's curvature)