New measurements of the sky's blackness
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New measurements of the sky's blackness
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Re: New measurements of the sky's blackness
#2There are far fewer *Visible stars and galaxies than we thought
Re: New measurements of the sky's blackness
#3There are far fewer *Visible stars and galaxies than we thought
> So, what could be the source of this leftover glow? It’s possible that an abundance of dwarf galaxies in the relatively nearby universe lie just beyond detectability. Or the diffuse halos of stars that surround galaxies might be brighter than expected. There might be a population of rogue, intergalactic stars spread throughout the cosmos. Perhaps most intriguing, there may be many more faint, distant galaxies than theories suggest. This would mean that the smooth distribution of galaxy sizes measured to date rises steeply just beyond the faintest systems we can see – just as there are many more pebbles on a beach than rocks.
Re: New measurements of the sky's blackness
#4This paper would seem to put many others estimating the prevalence of astrobiological activity into question.
Re: New measurements of the sky's blackness
#5Specifically, from the article:
> New measurements of that weak background glow show that the unseen galaxies are less plentiful than some theoretical studies suggested, numbering only in the hundreds of billions rather than the previously reported two trillion galaxies.
We used to think that we couldn't see 90% of the galaxies/stars, this study proposes that we can't say about ½ of the galaxies/stars.
Re: New measurements of the sky's blackness
#6This is the money quote:
> New measurements of that weak background glow show that the unseen galaxies are less plentiful than some theoretical studies suggested, numbering only in the hundreds of billions rather than the previously reported two trillion galaxies.
The new data is based on observations of the luminosity of deep space images from the New Horizons program, which is outside the inner solar system. The older estimate was based on Hubble images along with mathematical models to try to account for the glow of space dust.
Re: New measurements of the sky's blackness
#7There are far fewer *Visible stars and galaxies than we thought
This is more about the invisible stars and galaxies, the ones too far to actually count, but whose lights just gives a faint glow to the darkness.
Re: New measurements of the sky's blackness
#8This paper would seem to put many others estimating the prevalence of astrobiological activity into question.
I don’t think so. For astrobiology we are mostly looking for life in our galaxy, this study looks at presence of very far away galaxies. For purposes of communication those galaxies are forever out of reach as they are at such high red shifts they are escaping from us faster than speed of light.
Re: New measurements of the sky's blackness
#9Noob physics question: I assume this talks about stars close enough that we can receive their light. Can we say anything about the number of stars & galaxies that are further away than that?
Re: New measurements of the sky's blackness
#10Important to note, that this number refers to the “observable universe”. The number might be much higher, especially given inflation theory, but those galaxies currently lay outside our observable universe due to speed of light constraints.
Another interesting possibility is a finite but unbounded universe which means we might see duplicate galaxies from light circumnavigating (think of an old video game where you leave the screen at the top and appear on the bottom). In that case there might be fewer actual galaxies than what we observe.