When I decided it wasn't worth to extend the exposure of M 37 in the clear night in February 2022 more than what is valuable, I considered to give the spring time cluster M 67 a try. One year ago I wasted an evening by spending an exposure with a misaligned optics, so that would be the perfect time for reconciliation. And indeed it was...

I am still excited about the picture although it is less spectacular than plenty of stuff you are seeing on my page. But the splendid appearance of the cluster in front of the intergalactic voids of the spring time sky together with the colourful spectral resolution of the stars makes it a highlight in my gallery.

For a long time M 67 was the oldest open star cluster known. But why should we know about the age of star clusters at all? It's because the hottest - and bluest - stars are spending their fuel much faster than the others. That means they are ending up earlier in either red giants or - after this short episode - as "white dwarfs", faint stellar corpses without any active energy production. The point of luminosity at which we do no longer observe blue stars in star clusters can be used to determine the age of the population. For M 67 researchers determined an age of well above 3.5 billion years...

Messier 67 was discovered by the German astronomer Johann Gottfried Köhler in 1779.