CASTOR AND POLLUX: SO SIMILAR, BUT SO DIFFERENT

Dwelling in the celestial neighborhood of the Gemini constellation, the stars Pollux and Castor shine brightly. Pollux, having an apparent magnitude of +1.1, is marginally brighter than Castor, which boasts a magnitude of +1.5. Given their close proximity and nearly identical luminosity, it's no wonder they help form the constellation of Gemini.

However, beneath the surface, these twin stars are starkly different. A striking variance, visible even to the naked eye, is their color. Pollux, a red/orange giant, is situated 33 light-years from our Solar System. In contrast, Castor, a blue main-sequence star, is slightly further away, at a distance of 51 light-years. Their identical brightness and closeness in the night sky are purely a result of perspective.

Pollux shares a few characteristics with our star, the Sun. It has a mass of 1.8 times that of the Sun and is in a similar advanced evolutionary state, foretelling the Sun's future in several billion years. Like the Sun, Pollux is orbited by at least one planet, a gas giant discovered in 2006, with nearly three times the mass of Jupiter.

In stark contrast, Castor bears little resemblance to our star. Besides being considerably larger and more massive, Castor is part of a multiple star system, potentially comprised of six components. The two primary stars, Castor A and B, exceed the Sun in size, while the four potential components could be red dwarfs - small, less luminous stars. However, the existence of these four components remains uncertain.

Credit: Rogelio Bernal Andreo (Deep Sky Colors).