Category: Sky observation

Posts related to observational astronomy, or simply sky observation.

Ole Rømer and the finite speed of light

The first to observe that the propagation of light was not instantaneous was the astronomer Giovanni Domenico Cassini (1625-1712); the first to estimate its speed, in 1676, was the Danish astronomer Ole Christensen Rømer (1644-1710), both based their observations on the solar system.

pdf  Brussi 2026_Ole Rømer and the finite speed of light

 

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Milky Way bulge

The galactic bulge is indeed an incredibly dense region. While the solar neighborhood has a stellar density of roughly about 1 star every 250 cubic light-years), the central bulge reaches densities of millions of stars per cubic light-year. In the densest parts, stars can be separated by only a few light-days or light-weeks, compared to the 4+ light-years between us and Proxima Centauri.

 

link  read more on Black Hole X Channel

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Stars like gas molecules

Looking at photographs of galaxies, one gets the impression that they are gas clouds, as they were actually considered before the resolution of optical instruments allowed us to identify individual sources. As in these splendid images from HST (the Hubble Space Telescope) and VISTA (the Visible and Infrared Survey Telescope for Astronomy, part of ESO’s Paranal Observatory).

 

Young compact star cluster E269-58 by HST

Young compact star cluster E269-58 by HST on X Black Hole channel

Cat’s Paw Nebula in Infrared

Cat’s Paw Nebula in Infrared on X Black Hole channel

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Here I am

After a hiatus from 2021, I’m resuming my online presence with this small collection of suggestions, seeking intellectual dialogue. Let me know what you think in the comments or via email.
Thanks

p.s. I posted with the dates of the original documents

 

 

That's me

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