A celestial grandfather strolls low across the south on winter evenings. He’s represented by two stars. In the western world, they’re part of the constellation Columba, the dove. But in ancient China they were known as the Grandfather.

The stars are Alpha and Epsilon Columbae. Coincidentally, they’re about the same distance from Earth – about 280 light-years. And both are much bigger and brighter than the Sun. But there’s a big difference in their ages, so the stars aren’t related.

Alpha – the First Star of Grandfather – is the brighter of the two – the brightest member of Columba. It’s less than a hundred million years old – about two percent the age of the Sun. But it won’t be around much longer. It’s about four and a half times the mass of the Sun. Heavier stars age more quickly. In the next 150 million years or so, Alpha will move out of the “prime” phase of life and into the next phase, as a giant.

Epsilon has already reached that phase. It’s not as massive as Alpha, but it’s about one and a half billion years older – a third the age of the Sun. It’s puffed up to many times the size of the Sun, so it shines much brighter. Before long, though, it will cast off its outer layers, leaving only its hot, dead core – and Grandfather will be down to a single star.

Columba is low in the south-southeast at nightfall. Alpha and Epsilon are close together, near the center of the constellation.

Script by Damond Benningfield