Light years

Baby supernova seen right in our neighborhood

The supernova, known as G1.9+0.3, would have made a bright flash when it first exploded 140 years ago but was not seensupernova-180.jpg because dust obscures it, David Green of Britain’s University of Cambridge and colleagues reported.

The supernova is at the center of the galaxy, roughly 25,000 light-years from Earth. A light-year is the distance light travels in one year — about 5.8 trillion miles.

The article says that the supernova exploded just 140 years ago. It goes on to say that we are 25,000 light years away from it. So, how can we possibly be seeing it with light waves that take 25,000 years to reach us? Did it really explode 25,140 years ago, rather than 140?


If the star was at the center of our galaxy, as stated in the article, at 25,000 light-years away, how is it that the light from the supernova explosion has reached us in only 140 years?


A number of readers asked about this, and of course they have a point. Time frames such as this one are often referred to in Earth time – as in 140 years – rather than adding the number of years it took for us to see the event. Those are implied, and as you saw, we mentioned the light year distance later in our story. 

Other news organizations tended to handle this story the same way: GBU Editor


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