Sun, Moon, And Stars

The moon is Earth's only natural satellite, while the sun, Mars, and Venus are celestial bodies that do not serve as moons to other planets.

Stars are large celestial bodies primarily composed of hydrogen and helium gases that undergo nuclear fusion to emit light and heat. Asteroids, planets, and comets are not primarily composed of hydrogen and helium, nor do they emit light and heat in the same way stars do.

The sun is at the center of our solar system, around which all other planets revolve. The moon and other planets are celestial bodies that orbit the sun, but the sun itself is the primary source of light and energy.

The correct answer 'measure' means to determine the size, amount, or degree of something. The three incorrect answers 'calculate', 'estimate', and 'evaluate' all involve making judgments or arriving at a specific value, but they do not specifically refer to determining the size, amount, or degree of something.

A model is a simplified version of a real-world object or concept used to represent and understand the original.

A constellation is a group of stars that forms a recognizable pattern. It is different from a galaxy, asteroid, or nebula.

A shadow is formed when an object blocks light, preventing it from reaching a surface. Reflection is when light bounces off a surface, illumination is the act of lighting something up, and refraction is the bending of light as it passes through a medium.