Have you ever heard someone proclaim confidently that, actually, because light from distant stars takes thousands – even millions – of years to reach us, most of those pin pricks of light in the night sky are actually already dead?
It'a a fascinating idea. After all, when we look up at distant objects in the night sky, we're effectively looking back in time, because light from distant objects does indeed take thousands or millions of years to reach us.
More space myths explored
But what about the stars we see with the naked eye from our back garden or a dark-sky site?
Are they really so far away, their light travelling for so long, that they're actually already long gone?
Let's take a scientific look at this enduring myth.
What we actually see in the night sky
All the stars you can see with the naked eye lie within about 4,000 lightyears of Earth.
But the most distant ones you can see are intrinsically brighter, have more mass and are therefore likely to die in supernova explosions.
We can only see fainter (hence less massive) stars out to smaller distances, but these less massive stars are more likely to end their lives in less violent (but more common) deaths.
This complicates our estimates of the death rate for naked-eye stars. We can, however, choose an intermediate distance – say 1,000 lightyears – to estimate this number.
Using our knowledge of the rate of stellar deaths in the Milky Way, the death rate for visible stars works out at about one star every 10,000 years or so.
Given all those stars are closer than 4,000 lightyears, it’s unlikely, though not impossible, that any of them are already dead.
However, using a powerful telescope brings many more distant stars into view, increasing the chance that some have already died.
This article appeared in the June 2025 issue of BBC Sky at Night Magazine
