Which major constellation is positioned opposite of the Big Dipper on a star map?

Cassiopeia is indeed the correct answer because it is situated opposite the Big Dipper in the night sky. Both constellations are part of the circumpolar group around the North Star, Polaris. The Big Dipper, which is part of Ursa Major, stretches in a different direction, while Cassiopeia forms a distinctive W shape. As the Earth rotates, both constellations remain visible throughout the year in northern latitudes, creating a visual counterpoint to each other.

Orion, Hercules, and Centaurus, while significant constellations, are not in opposition to the Big Dipper on a star map. Orion is more prominent in the winter sky and does not have a direct relationship in positioning with the Big Dipper. Similarly, Hercules and Centaurus are located in different areas of the sky and are not positioned directly opposite the Big Dipper. Therefore, Cassiopeia's placement makes it the correct choice.