There’s a double burst of color in the sky right now. The planet Mars and the star Pollux stand side by side. They’re in the east at nightfall and soar high across the sky later on. Mars is by far the brighter of the two, with Pollux close to its left.
Mars and Pollux both shine bright orange. But they achieve that color in different ways.
Mars is a planet – a chunk of rock and metal about half the size of Earth. Much of its surface is coated with dust. It’s made mostly of iron oxide – it’s basically rust. And if you have any rusty iron pipes, you know it looks orange.
That dust could be a problem for future Mars explorers. It’s so fine that it could get into machines and electronics. That could jam any moving parts, and short out the electronics. So mission planners will have to find ways to prevent astronauts from tracking the dust into their habitats.
Pollux, on the other hand, is a star. And it’s an impressive one: It’s about twice as massive as the Sun, almost 10 times wider, and more than 30 times brighter.
Pollux is so large because it’s burned through the original hydrogen fuel in its core. That’s made the core smaller and hotter. Radiation from the hotter core pushes on the surrounding layers of gas, making them puff up. As the gas expanded it got cooler. So the surface of Pollux is a couple of thousand degrees cooler than the Sun. At that temperature, the gas glows orange – a bit of color in the night sky.
Script by Damond Benningfield