Starship Asterisk*

Funny, I was surprised by seeing a globular cluster (47 Tuc) so close to the SMC. I've never appreciated that fact; I guess that detail has never sunk in
I really like that image.

... WR 40 is a WC8 class of a Wolf Rayet star, and I found this info on WC8 stars in a table in the Wikipedia article about WR stars: Temperature: 60,000 K. Radius: 6.3 solar. Mass: 18 times solar. Luminosity: 398,000 solar. Absolute magnitude: −5.32. ... Ann, looks like your spectral type is not c...

Nice image. I appreciate the version on the left that shows a realistic depiction of actual naked-eye visibility. (Also, a great advertisement for https://www.startrails.es/ .) The image on the left is nowhere near a depiction of naked-eye visibility. It offers a sense of scale, and that's all. To ...

Question: this explosion happened about 1,000 human-years ago. And now it's 10 LY-wide. Is that speed of light possible? My brain can't figure it out... First thing to note is that a light year is not a measure of time, but a measure of distance. Now if the Crab Nebula spans 10 ly, then it's radius...

I believe alter-ego has the correct location of the progenitor pulsar, though it was hard to find another source. From http://www.scienceworldreport.com/articles/1353/20120216/cold-wind-crab-pulsar-produces-very-high.htm#page1 https://1248916936.rsc.cdn77.org/data/images/full/383/cold-wind-of-the-c...

I believe alter-ego has the correct location of the progenitor pulsar, though it was hard to find another source. From http://www.scienceworldreport.com/articles/1353/20120216/cold-wind-crab-pulsar-produces-very-high.htm#page1 https://1248916936.rsc.cdn77.org/data/images/full/383/cold-wind-of-the-c...

richardschumacher wrote: ↑Sun Jan 15, 2023 4:12 pm Can you add an arrow to indicate the central star? It's difficult to pick out in this highly detailed image.

Pulsar identified.

Sorry, I was not quite correct on numbers and plots. Blackbody Calculator generates spectra on wavelength λ and I proclaimed bluishness for spectra on frequency ν. Both kinds of spectral functions are called Planck's law and, for a narrow band with photon energies much lower than kT, such as visibl...

100000K.png https://asterisk.apod.com/download/file.php?id=46319&mode=view A plot with a flat line at the zero height would be unfriendly, so a zero above the horizontal axis is used. What Rayleigh–Jeans law says, B ~ ν²/T, dictate the Brightness, or Spectral Radiance, to fall (.4/.1)² = 16 tim...

I guess I was thinking that at the poles, the stars paths are circles around the poles, so why wouldn't the moon's path look similar? Plus, this pic apparently shows the moon's progress over 1.5 hours, which is 16th of the total 24 hour path, so why doesn't it show a slight curve? (Of course, the m...

The extreme linearity of the path of the moon across the sky perplexes me. And it's parallel to the horizon to boot. Is this something special due to this being at the south pole, or would the path be so linear everywhere on earth? Sadly, I expect my 3D sense is failing me yet again. How could the ...

I think the featured analemma is a fake. The size of the Moon in the image is doubled or even tripled in respect the real size of the Moon. Please compare with this: https://apod.nasa.gov/apod/ap050713.html Hmm. Not sure what to make of that. Hopefully Chris or someone else will comment. The result...

Nice! First pic of Europa from Juno! Twenty years after the last close-up from Galileo in 2000. Will Juno be making more passes, or is this the one and only? I read the links, but that didn't seem to be mentioned. Yes, more flybys will happen. In its extended mission now, counting this pass, the pl...

I second Ann's perplexity about "Io's shadow". I'm still not sure what that really is, or means, or even what the arrow in the pic is pointing to (if meant to refer to something other than the southern aurora). Though fairly complicated, here's a simplified explanation. It's not a new thi...

Pretty pleasant "music of the (planetary) spheres". Does the eccentricity of the circle representing the planet mean anything? I don't know why the sky in this video has been distorted in the way it has. At least, it would be nice to have some information as to what conformal mapping was ...

Cross your eyes to see the Hasselblad stereo view. Apollo 11 Stereo View.jpg It's amazing to me. As a kid, I loved going to my grandparents' house to use their wooden stereo viewer to look at the old B&W stereo cards of steam engines, trains, and industry. Now I'm at my computer screen looking a...

Each projection describes a particular diffraction behavior in that context, but point-to-point deviation is not the sole definition of diffraction or diffraction structures. The "diffraction pattern" intrinsically includes interference. If you include measuring energy quanta, you'll then...

That's a reasonable way to understand the broad picture. Just keep in mind that there are two related but different things going on. You have diffraction, which results in light that ideally would create a perfect point being distributed outside that point by how it interacts with edges and obstruc...

With one hexagonal segment, yes. It's just what a camera on a backyard telescope would see if the scope was fitted with a hexagonal mask at the aperture and a narrowband filter. You could think of it that way (although even the min sections are brighter than zero, so appearance depends a lot on how...

Whether JSWT uses mirrors and or lenses to focus the light onto the detectors I'm not sure. It's ok to use flat "lenses" to filter the light. It's not ok to use concave or convex lenses to focus the image, because it would destroy multi-chromatic image resolution. A good Newtonian reflect...

... Update. Come to think about it, could the ISS be partialy shadowed? I think normally we don't notice satellites when shadowed; they must be colored and changing the color to red and dark red, but be much dimmer — like Moon looks red at an eclipse, but much dimmer, too. Tom Glenn however was not...

Does anyone else get an impression that the star field rotates slightly between the still image and the trailed image? I get a strong impression of rotation near the pole, but no such impression far from the pole. My GF gets no such impression in any part of the image. Weird. Yes, presumably becaus...

... But what exactly is causing the dashed lines on the sides...? I missed answering this part. As the description states, the dashed lines are extended exposure times so that the sun trails instead of just forming a dot. The intermittent dark regions within trails are clouds blocking the sun. Than...

johnnydeep wrote: ↑Sat Jul 02, 2022 8:51 pm ...
But what exactly is causing the dashed lines on the sides...?

I missed answering this part. As the description states, the dashed lines are extended exposure times so that the sun trails instead of just forming a dot. The intermittent dark regions within trails are clouds blocking the sun.

I truly don't understand how this image was made. Oh well, analemmas seem to be my nemesis. Sure, the three differently positioned analemmas are from three times an hour apart (why three?), taken by a pinhole camera every day over a year. But what exactly is causing the dashed lines on the sides, a...