Yesterday, an image went viral on social media that showed a neon pink glow in the distant San Jose skyline. This looked like something straight out of a sci-fi movie which is perhaps why it gained so much attention. It’s fair to say that this isn’t a typical sight that you’d expect to see when looking at the sky.

The image was first shared on Reddit by a curious resident who was unsurprisingly baffled by the strange sight. This got a number of comical responses, with one user even jokingly adding that it was Pink Poodle who got a new sign. Others even claimed it was a Batman signal. However, the truth is far less fantastical and is actually a weather phenomenon.

It turns out that this is called Raleigh scattering. This is when sunlight interacts with air molecules, it scatters in all directions. The shorter wavelengths of light, such as violet and blue, are scattered more than the longer wavelengths, such as red and orange. This is why the sky appears blue during the day.

However, at sunrise and sunset, the sunlight has to travel through a thicker layer of atmosphere to reach our eyes. This means that more of the shorter wavelengths of light are scattered away, leaving behind the longer wavelengths of red and orange. This is why the sky appears pink or orange at sunrise and sunset. Over the years, San Jose has frequently seen this happen in its skies, meaning that as spectacular as yesterday was, it wasn’t anything too extraordinary.