Starship Asterisk*

This occurred when there was only one landmass on Earth, Pangea. The area that became Quebec was at a lower latitude, probably not far north of the tropics. The radiometric dating methods used to determine the age of the event are very well developed, so the 215 million year determination is almost...

Lots of interesting questions arise! How accurate are age estimates? The text says 215 million years, 1 million years plus or minus, so cannot have caused Triassic-Jurassic die-off at 201 million years. Percentage of error possible at that remove, for each estimate? Also, where was Quebec back then...

Lots of interesting questions arise! How accurate are age estimates? The text says 215 million years, 1 million years plus or minus, so cannot have caused Triassic-Jurassic die-off at 201 million years. Percentage of error possible at that remove, for each estimate? Also, where was Quebec back then...

Orbiting 400 kilometers above Quebec, Canada, planet Earth, the International Space Station Expedition 59 crew captured this snapshot of the broad St. Lawrence River and curiously circular Lake Manicouagan on April 11. April 11? Which one? I guess the one in 2019? As Expedition 59 was from March th...

So, I'm reading that tiny NGC 3165 is also part of this triple, and at about the same distance, yet it doesn't seem to be interacting with the other two at all, either currently or in the past. Why not? First, these interactions are tidal . That means they occur when extended bodies are close enoug...

Thanks for that reference, Ann. It makes it very clear what is thought to happen. Do we know of any experiments to replicate this? Maybe when neon signs were being invented?i Speaking of seeing auroras at low latitude, I did see the 1989 event, living then in Massachusetts near Boston, about 41 deg...

It seems obvious to me that it is harder to create a blue nitrogen aurora than a green or a red oxygen one. Since the blue aurora is so rare, it has to require a lot of energy to create it. But in the many pictures of auroras that have been submitted to Starship Asterisk* and other sites from the l...

I’m having a hard time finding a coherent explanation of what causes the different colors. O2 molecules split because of ultraviolet light, then the O atom picks up an “ambient” electron, (not from the sun , only “particles” come from the sun, not protons and electrons) causing emission of green li...

TedH wrote: ↑Mon May 20, 2024 12:19 pm The position of the North Star seems low. I'm in Brookfield, Wisconsin, which is south of Arlington, and Polaris is never that low in the sky.

A wide angle image like this is strongly distorted. You can't compare what it shows to what your eye sees.

I just re-read Clarke's 1971 short story A Meeting with Medusa about a dirigible pilot who ventures down into the upper levels of Jupiter's atmosphere (and discovers life there). Kind of like the APOD, but in slow motion.

Roy wrote: ↑Sun May 19, 2024 4:27 pm

Chris Peterson wrote: ↑Sun May 19, 2024 2:50 pm

Roy wrote: ↑Sun May 19, 2024 2:40 pm Copyright said 2017 - I am sorry I have not seen this in the 28 years since then!

???

Yeah - meant to say 8 years. Probably age-related error. Hate it when that happens.

Oh well... I was hoping you had access to some kind of time machine.

Roy wrote: ↑Sun May 19, 2024 2:40 pm Copyright said 2017 - I am sorry I have not seen this in the 28 years since then!

???

NGC 2903 A pretty spiral galaxy in Leo, with a very obvious bar (estimated to contain 20% of the galaxy's mass), tightly wound arms, and a lot of starburst activity in the center. Details: QSI 660 camera on 250mm RC, Astronomic RGB filters. 40 minutes each red, green, and blue. Processed with PixIn...

The lower blue part of the Belt is just the twilight sky rising (or setting). In the evening I sometimes call it "nightrise". So yeah, it is only lit indirectly, by light that has scattered from air still lit by the Sun directly. So every moment of twilight involves some combination of di...

The Belt of Venus illustrates this. The upper pink part is directly lit by the Sun. The lower blue part is only scattering light from other parts of the sky. When I think of Descartes on clear and distinct ideas, where “distinct” perceptions are "sharply separated from all other perceptions&qu...

Astonishing !! :shock: !! From my non-astronomer/non-scientist point of view, I must presume (given the clarity of today's APOD) that the almost infinite orders of magnitude greater cost for other platforms must in some manner provide significantly greater information. I *hope* so. An image like th...

Amazing photograph! How was this taken? Was it from a space platform, an observatory, or from a portable ground based telescope? This latter seems quite improbable; however, I did follow the link to the photographer's website (where could not find this image) and his other images do seem to be made...

The Belt of Venus illustrates this. The upper pink part is directly lit by the Sun. The lower blue part is only scattering light from other parts of the sky. Regarding the lower blue part, which is the Earth's shadow, I wonder if the blue color is not a function of Rayleigh scattering but instead C...

The link to the "webda" page mentioned (https://webda.physics.muni.cz/cgi-bin/ocl_page.cgi?dirname=ngc2169) shows a "Log age" of 7.067 and 10 the power of that is about 11,668,096.17 😊 That's because you have a cheap calculator. Mine has more digits, so I know the age of this cl...

Log Age What about it? The link to the "webda" page mentioned (https://webda.physics.muni.cz/cgi-bin/ocl_page.cgi?dirname=ngc2169) shows a "Log age" of 7.067 and 10 the power of that is about 11,668,096.17 😊 That's because you have a cheap calculator. Mine has more digits, so I ...

LOG Age = 7.067 means 10^^7.067, which on my Casio shows 11,668,096. No, it means "about 11 million years". Or maybe, "about 11.5 million years". All but the first few digits are insignificant, and when you write them out it results in a misleading number, that might fool somebo...

Roy wrote: ↑Tue May 14, 2024 6:09 pmLog Age

What about it?

The color green does not exist outside our human eyes and brains. It is our eyes and brains that "create" the color green. Also then should be the case regarding the sun's green flash, it is an optical phenomenon, as our eyes and brains also create the color green of the sun's green flash...

I wonder if this Wikipedia article on Sky brightness makes sense -- it seems to that there is both direct and indirect sunlight in the sky at twilight -- "Indirectly scattered sunlight comes from ... the atmosphere itself .... the Sun has just set but still illuminates the upper atmosphere dir...

Hopefully someone can clear up some sun confusions for me. Today's APOD shows AR-3664 towards the BOTTOM of the solar disk. That of May 11 showed this cluster to be towards the RIGHT. Does the apparent orientation of the sun shift from day to day? My understanding is that the storms move from left ...