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Gin Gardner
why wait for something good to happen?
why wait for something good to happen?


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“We know the size of the Observable Universe since we know the age of the Universe (at least since the phase change) and we know that light radiates. […] My question is, I guess, why doesn’t the math involved in making the CMB and other predictions, in effect, tell us the size of the Universe? We know how hot it was and how cool it is now. Does scale not affect these calculations?”

Our Universe today, to the best of our knowledge, has endured for 13.8 billion years since the Big Bang. But we can see farther than 13.8 billion light years, all because the Universe is expanding. Based the matter and energy present within it, we can determine that the observable Universe is 46.1 billion light years in radius from our perspective, a phenomenal accomplishment of modern science. But what about the unobservable part? What about the parts of the Universe that go beyond where we can see? Can we say anything sensible about how large that is?

We can, but only if we make certain assumptions. Come find out what we know (and think) past the limits of what we can see on this week’s Ask Ethan!

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“Regardless of the mechanism in question, we can be certain of one conclusion: the reason for the dimming of Boyajian’s star is due to dust. This is normal, particulate dust, containing particle sizes down to about 100 nanometers, or smaller than the wavelength of visible light. The same dust that causes short, day-or-less dips also causes dips that last many months, and also cause the decline that’s lasted more than a century. It’s all due to plain, normal dust.

The big, open question that now remains is where this dust came from? It’s not because the star is young or still forming, and there are incredible constraints on the star having an unseen companion. It cannot all come from interstellar dust. Was a planet devoured? Is there something even more unusual afoot? The only way to know will be with more — and better — science on this object. But one thing’s for certain: even if alien megastructures exist somewhere, they aren’t here.”

A few years ago, NASA’s Kepler spacecraft observed a most unusual star: KIC 8462852. Unique among all the stars in its field, it displayed enormous flux dips, but they were irregular. When we went back through the data, we also found that this star has been dimming, consistently but irregularly, over more than a century. Many ideas were proposed, including swarms of comets, debris from planetary collisions, or even alien megastructures. All of these ideas and more, however, fell apart with further observations.

The result? We know it’s dust that explains it all. But where does the dust come from? That’s still a mystery. Here’s what we know so far.

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IC 4628 - Prawn Nebula in SHO Hubble Palette

I had a lot of fun processing this one. The [O-III] emission lines are quite strong here creating this beautiful turquoise color in the background that helps the yellow-gold to stand out more.

I hope you like it!


The Prawn Nebula, also known as IC 4628 and Gum 56, is an emission nebula located in the constellation Scorpius. It has an apparent magnitude of 7.31 and lies at a distance of 6,000 light years from Earth. Located to the south of Antares, the nebula is about 250 light years in diameter, corresponding to an apparent size of 1.5 degrees, or 3-4 times the size of the full Moon.

It is a stellar nursery that contains a large number of very hot, luminous, young stars, formed out of the surrounding gas. These stars include two large, hot, blue-white giants belonging to the rare spectral class O. O-type stars have a relatively short lifespan as they tend to burn out very quickly before ending their lives in supernova explosions and collapsing into either neutron stars or black holes. The blue giants in IC 4628 will end their lives after only about a million years. The material produced by their supernova explosions will be used to form new stars in the nebula.



- OTA: Orion 8" f/3.9 Newtonian Reflector
- Upgraded with Moonlite 2" CR focuser
- Mount: Celestron AVX
- Polar Alignment: QHY PoleMaster
- Imaging Camera: Atik 383L+
- Guiding Telescope: Orion 80mm short tube refractor
- Guiding Camera: Starshoot Autoguider
- Filters: Baader HA 7nm, OIII 8,5nm, SII 8nm Baader MPCC Mark III Coma Corrector
- Frames: 32 x HA 120, 10 x HA 150s, 10 x HA 180s, 15 x OIII 120, 10 x OIII 180s, 15 x SII 120s, 10 x SII 180s.
- Software: SGP, PHD2, Pixinsight, Lightroom,
- Location: Puerto Varas, Chile
- Date: 02/07/2018, 03/07/2018

Processing Details

- Image Calibration
- Cosmetic Correction
- Image Registration
- Image Integration

Then worked each channel separated.

- Deconvolution (PSF, Range - Star mask)
- Multiscale Linear Transform
- Multiscale Median Transform
- Histogram Transformation (from STF's auto stretch)
- HDR Multiscale Transform
- Local Histogram Equalization
- Curves Transformation

O3, S2
- Multiscale Linear Transform
- Histogram Transformation (from STF's auto stretch)
- Local Histogram Equalization
- Curves Transformation

And then I used Pixel Math to combine them:
- Pixel Math (R: SII, G: HA, B: OIII)
- Background Neutralization
- Color Calibration
- SCNR (Green)
- ACDNR (Chrominance)
- Color Saturation
- Invert - SCNR (Green) - Invert
- LRGB Combination (L: HA)
- Morphological Transformation (to shrink stars)

- Curves, Saturation

#astrophotography #telescope #universe #sky #starrynight #deepsky #astrophoto #prawn #hubble #chile

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National Aboriginal Languages Day is Saturday, March 31. If you believe in keeping Indigenous languages alive visit and share the video.

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Between the Planets and the Stars

Stars undergo nuclear fusion in their cores, while planets don't. But between the largest planet and the smallest star lay brown dwarfs.
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