Contrasting open clusters: M35 and NGC 2158
The cluster on the left (M35) appears larger than the one on the right (NGC 2158) because at a distance of a 'mere'
2,700 light years, M35 is less than a sixth of the distance to NGC 2158. M35 is believed to be 'only' 95 million years
old and so it is dominated by 'young' brilliant blue-white stars. NGC 2158 has been around for more than a billion
years and so a far higher proportion of its stars have evolved into red giants, giving this cluster a more mellow hue.