Starship Asterisk*

As previous posts would have it, those meteors are coming in at 60 miles per second. Care to speculate why some streaks show TWO bright finish burnout flares? 60 km/s. Meteors can't be as fast as 60 miles per second. Meteoroids are very non-uniform, especially when they are cometary dust, which is ...

This animation is wrong. The Perseids must cross the ecliptic close to the Earth in a direction opposite to the motions of the planets. Their speed relative to Earth is about 60 km/s, but in the animation it would only be about 20 km/s. In other words, their orbit is retrograde, not prograde. Their...

M20 is a tricky target for me, because it's low in the sky and there's a tree blocking it about where it's passing highest. So I shoot it through the tree, and the result is those weird, JWST-like diffraction spikes around the bright stars, caused by tree branches! I like diffraction spikes. :ssmil...

It goes without saying that I dislike nebula images where stars have been suppressed. What's the point? But look at the stellar background of Emmanuel Astronomono's image. Isn't it glorious? https://dq0hsqwjhea1.cloudfront.net/sandt-1.jpg Not only do we see "more or less foreground" stars...

This image doesn't do much for me. Partly because of the low contrast and low saturation, and partly because the stars have been suppressed... something easy to do these days, and which always results in images that lose all their aesthetic appeal to me. The depth of the image is interesting in how...

As Christian surmised, I'm not too happy with the non-blue appearance of the blue hue of the reflection nebula part of the APOD. Let's compare the APOD with a picture that I like very much myself: https://le-cdn.website-editor.net/s/776ab31444b54f92ac26f7da5c0aa074/dms3rep/multi/opt/M+20+LRGBHaO3S2...

The second law of thermodynamics says that the entropy of a system is always increasing, and so eventually everything will be in a state of max disorder and "evenly mixed", but looking scenes like the Triffid Nebula (estimated age 300,000 years) it's difficult to imagine that the universe...

What are the several splotches of orange seen on the Earth's surface (or in it's atmosphere)? Fires? Volcanos? Lightning? Cities, I'd think. Really? Hmm... Sure, why not? It's exactly the right color for the typical sodium lamp city lighting we often see on ISS shots of the night side, and it's not...

johnnydeep wrote: ↑Fri Aug 09, 2024 5:59 pm What are the several splotches of orange seen on the Earth's surface (or in it's atmosphere)? Fires? Volcanos? Lightning?

Cities, I'd think.

What would have happened if such a meteor as in the photo had hit the ISS? I have a little experience with bullets, such as the 5.56 mm bullets fired on j13. They weigh 4.02 gm, travel at 914.4 m/sec. They will dimple 6 mm mild steel, bounce off 6 mm plow steel. According to the post, the meteors a...

What I can't figure out is why an army of robots would want to colonize the Milky Way. What would be the point? Colonize, no. As you say, to what point? Even if those robots were somehow interested in reproducing themselves continuously, why would they choose planets? Space is much bigger. But expl...

What would have happened if such a meteor as in the photo had hit the ISS? It would depend where it hit. Critical parts of the ISS are protected by shields that will block particles smaller than about a centimeter. The meteor in the image was probably produced by a particle only a few millimeters i...

Modern digital astronomical image making has opened up capturing the spectacular nature of celestial objects to a much larger number of astronomy buffs than was possible when I was younger, and we are all the richer for it. Not only are these images qualitatively head and shoulders above the imager...

I knew it! Today's APOD sure looks like a circa 20-30 year-old comet picture - and it is, too! Rhemann799_109P_24_11_92_1100px[1].jpg Periodic Comet Swift-Tuttle Image Credit & Copyright: Gerald Rhemann You can tell the picture is old because of the lovely colors. The comet head is cyan-green, ...

I can' figure out why the colors are so well separated. The orange part of the cloud appears to be the same shade of peach, although admittedly the very bottom part appears to be a tad redder. And the yellow part of the cloud is almost the same shade of lemon overall. https://apod.nasa.gov/apod/ima...

Following the link to the Permian extinction, we are given asteroid “as big as Everest” estimates from 6 to 12 km diameter. This ( V = 4/3 x pi x r*2 ) which calculates from 112.8 to 902.5 cubic kilometers, a wide range. Supposing it to be of granite, density ~ 2.7 grams per cc, the mass ranges fro...

Hmm... don't ask me to explain how or why, but I note that the same thing happens to the sky during sunsets. https://i.pinimg.com/474x/da/5c/82/da5c8222da87a6780b45fc25f171fdba.jpg https://img.freepik.com/premium-photo/blue-sky-colors-sunrise-sunset-dark-blue-yellow_1018894-509.jpg Ann We don't see...

In contrast, the yellow color of the cloud's top results from reflection of light from a not-yet-setting Sun, where some -- but less -- blue light is being scattered away. Ok, this seems to be implying that the red bottom color is ALSO due to blue light being reflected away. If so, why is more blue...

Nice Star Wars trivia. But why is it called "Lars Homestead" in the movies? The Skywalkers lived there on Tatooine, not the Lars family. Wikipedia failed to enlighten me. See https://en.wikipedia.org/wiki/Tatooine for several mentions of "Lars Homestead" but no explanation of th...

As has been explained the glory is not a particular object in the sky, but the effect of backscattering of light rays from the sun from a particular set of raindrops in the sky in front and below you. The same can be said about the rainbow: Every person observes their own rainbow produced by reflec...

Alright. There's that "column of darker air" as opposed to a "shadow" distinction again. The text refers to cast shadows - the "shadow of the observer" - , so that's what I was regurgitating. And I assume you meant "cast by a plane" not "cast on a plane&...

That makes no sense to me. Why? But I assume if the "glory" is caused by the shadow of another object that you - and others - are inside (like an airplane), then everyone sees the same exact glory, no? And of course, if you and your buddy are side by side, and in actual contact, you would...

That would imply that the the one seen in this pic is that of the photographer, not the motorcyclist in the photo... is that the case? Yes. You can't see or image somebody else's glory. That makes no sense to me. Why? But I assume if the "glory" is caused by the shadow of another object t...

"Fun fact" about glories: If you see a glory and are acompagnied by other people, you will only see a glory around your own head. That would imply that the the one seen in this pic is that of the photographer, not the motorcyclist in the photo... is that the case? Yes. You can't see or im...

A comet with a 70-year period isn't returning to the Oort cloud! (Wikipedia tells me that Olbers has an aphelion of 32 AU but the Oort cloud starts around 2000 AU out.) Yeah, that's an odd assertion. It gets about as far from the Sun as Neptune (although orbiting on a different plane). That would b...