Starship Asterisk*

m.clayton wrote: ↑Sun Oct 27, 2019 6:25 pm I see a Firebird in flight over the ghost of the cafeteria lady at my elementary school.

Either that, or a Nice Hat over a face with huge deep-sunk eyes and an ankle-length beard.

Gandalf's Ghost...?

I've seen ISS several times from my back garden, but I'll always remember the time I happened to be outside at dawn and saw it coming over the trees in next door's garden. It was incredibly bright — the sunlight must have been bouncing straight down from all the solar panels at once, very different ...

Anyway, today's APOD reminded me of this unforgettable scene from 2001: A Space Odyssey. Johann Strauss' An der schönen blauen Donau will surely never be the same! I dunno, the music that came to my mind was whatever was used in the animation "The Inner Life Of The Cell" , which did an IM...

What's the significance of all the organics in the Plutonian atmosphere? We get excited by seeing methane on Mars. They're probably Tholins , (mostly) hydrocarbon compounds created from simpler surface and atmospheric chemicals due to UV from the sun and cosmic radiation from everywhere else. It's ...

There's really no need to invoke interstellar bodies when considering impacts with planets. There are vastly more bodies within our own solar system that can become planetary impactors, and an impact from a solar system body is billions of times more likely than an impact from the occasional inters...

Something I suspected when I saw the perihelion distance of 2AU — the hyperbolic orbit (there are diagrams on the Wikipedia page) is very open and flat. I'd guesstimate it's going to be deflected only about 30° or so as it passes the sun; definitely going at a considerable rate of knots, even faster...

A fascinating picture. I notice there are fainter loops around the outside; presumably this is a swirly sort of connection between the brightly glowing loops of warmer gas and the surrounding much larger invisible mass of cold gas? Now I can't help wondering what our solar system looked like at this...

madtom1999 wrote: ↑Sat Oct 12, 2019 10:07 am I've never seen that big arrow?

Look at where it is — down below the Earth. It's only visible in the southern hemisphere.

Something that just occurred to me, from that comment about the HII regions churning out lots of massive stars. They burn fast and pop as supernovae fast, so are we seeing a lot more SN eruptions and remnants than average in those regions?

Ah, I see what's happened — the English version of the Wikipedia page is the only one that doesn't have the proper photo of NGC 7715. That's quite a mangled galaxy there, it seems both of them are being chopped into little bitty pieces by each other's gravity. I wonder if galaxies are ever completel...

I notice that the caption describes NGC 7715 as "off to the left". Are there any good photos of it? I can't find any; the Wiki pages for 7715 and 7714 both show the same picture, similar to today's. Presumably it's at the end of the "shrapnel" of bluish clusters trailing away fro...

neufer wrote: ↑Tue Oct 08, 2019 3:15 pm

TheOtherBruce wrote: ↑Tue Oct 08, 2019 2:26 pm Maybe there's a connection to red aurora filaments being due to atomic oxygen.

Oxygen is primarily green...nitrogen is primarily red.

Whoops, looks like I misunderstood the Wikipedia section on auroral colours.

Ann wrote: ↑Tue Oct 08, 2019 4:09 am Interesting. The upper and lower structures of these phenomena are quite different.

Why are these things red?

Maybe there's a connection to red aurora filaments being due to atomic oxygen. If so, it's probably saying something relevant about the energy levels involved.

Heh — I've been waiting months for the chance to slip in that particiular Pythonism.

BDanielMayfield wrote: ↑Mon Oct 07, 2019 6:06 pm I did some reading also to find an answer to Ann's question, (not being too lazy to google), but I was too lazy to post a reply. Happily though TheOtherBruce has made up for my lapse. You're a credit to our name sir!

<raises hat, bops self on nose with one of the corks tied to the brim>

It has long been known that Saturn has a rocky core, and it has long been suspected that Jupiter may not have one. So, because I'm too lazy to google, would someone enlighten me as to why Jupiter doesn't seem to have a rocky core? The Wikipedia page on Jupiter suggests any original core could have ...

I think we can safely call this a starburst galaxy? Those are some really huge HII regions; there must be massive numbers of spectacular nebulae in them. Hmm... I followed the link to the 2016 picture, and I'm surprised there are so few (and much smaller) visible HII regions. I think I've matched up...

Those two nebulas look similar when you crop and rotate them to match, but MyCn 18 likely at a much younger stage. NGC 3132 is probably older and in a less organized stage. I don't think the same thing is causing the star appear off center, and the two apparent ringlike structures are only incident...

https://upload.wikimedia.org/wikipedia/commons/thumb/6/6a/Elements_abundance-bars.svg/1920px-Elements_abundance-bars.svg.png The gases thrown off by these geriatric Sun-like stars simply reflect the abundances of the elements in the Solar System :arrow: I.e., mostly: Hydrogen, Helium, Oxygen, Carbo...

The ionizing star of a planetary nebula is always pink in images in nitrogen/hydrogen/oxygen data processed with this standard palette. I'm probably missing something obvious, but I've always wondered why those three elements in particular (well, the nitrogen and oxygen anyway) are chosen so often ...

The “grand finale” link takes you to a very interesting link that states “Throughout the mission, Cassini has primarily relied upon its reaction wheels for fine adjustments to its orientation, especially during science observations.” So... I’m left wondering what Cassini’s “reaction wheels” are. Th...

Those figures are intriguing; 1500 light years away, and over 5000 years ago. Could there be a written (or chiselled) record somewhere, maybe one we know about but just don't understand yet?

Interesting, I haven't heard of this type of lightning before. Would it be safe to assume it also happens on other planets that have the right atmospheric conditions?

Ah, OK, I missed that bit about the planet having an at least partly hydrogen-helium atmosphere. Now I'm leaning more towards a mini-Neptune, where there might not be a solid surface at all apart from a possible rocky core.

8 times the mass of Earth? We are going to have to be SUPER SAYANS to do anything there.... got anything smaller???? The figure for density (from the Wiki article) is awfully low, juggling the numbers gives a surface gravity only a little bit more than Earth's. Which makes me wonder, what kind of p...