Why does Mars' appear fainter than Venus, as seen from Earth?

Might it be that it further from the source of light, the sun?

Mars appears fainter than Venus when seen from Earth due to a combination of several factors, including their distance from Earth, their sizes, and their reflectivity.

One of the main factors is the distance between Mars, Venus, and Earth. Venus is much closer to Earth than Mars, which makes it appear brighter. On average, Venus is about 41 million kilometers away from Earth, while Mars is around 78 million kilometers away. The difference in distance causes Venus to receive more sunlight and appear brighter in the night sky.

Another factor is the sizes of Mars and Venus. Venus is almost the same size as Earth, while Mars is smaller. The larger size of Venus means that it reflects more sunlight, making it appear brighter than Mars.

Lastly, the reflectivity of each planet's surface plays a role. Venus has a thick atmosphere that reflects a significant portion of the sunlight it receives, which contributes to its brightness. Mars, on the other hand, has a thinner atmosphere and a relatively darker surface, which absorbs more sunlight rather than reflecting it.

In summary, Mars appears fainter than Venus when seen from Earth because it is farther away, smaller in size, and has a less reflective surface.