Starship Asterisk*

These kinds of gradients are distributed over thousands or even millions of light years. They simply aren't significant over one light year. Ok, but then how close are nearby stars getting to our sun to nudge Oort cloud objects as I've often seen posited as the cause of some mass extinctions on Ear...

The tidal forces are infinitesimally small on the scale of something the size of a planetary system. There would be no detectable impact. Well, couldn't there be an increased chance of nearby star perturbations nudging Oort cloud objects inward and thereby increasing the likelihood of planetary imp...

APOD Robot wrote: ↑Thu Jun 04, 2020 4:05 am It also reveals a small galaxy nearby, likely a satellite of NGC 3628

So, is this the nearby small galaxy being referred to?

Let's say you had a solar system in one of these tidal fields...would life on a planet go on as normal? I know this would be an incredibly slow process. The tidal forces are infinitesimally small on the scale of something the size of a planetary system. There would be no detectable impact. Well, co...

...just how dense are these dust clouds? I'm thinking they would be much less dense than water vapor clouds on earth. Most cosmic dust particles measure between a few molecules & 10 -7 m. The light-year is ~10 16 m Hence, the optical cross section: σ d ~ (10 -7 m) 2 Optical depth τ d ~ [σ d x 1...

https://www.esa.int/var/esa/storage/images/esa_multimedia/images/2003/05/ngc_6523_lagoon_nebula/10180764-2-eng-GB/NGC_6523_Lagoon_Nebula_pillars.jpg Sometimes I just can't point to a feature of an image based on the description given. Like here: "Visible near the image center, at least two lon...

Sometimes I just can't point to a feature of an image based on the description given. Like here: "Visible near the image center, at least two long funnel-shaped clouds, each roughly half a light-year long". Just what funnel-shaped clouds is it referring to? At the center of the image I do...

https://apod.nasa.gov/apod/calendar/S_200601.jpg The Lively Center of the Lagoon Nebula Explanation: The center of the Lagoon Nebula is a whirlwind of spectacular star formation. Visible near the image center, at least two long funnel-shaped clouds, each roughly half a light-year long, have been fo...

Does anyone know what the object, visible in the full sized view, at approx. 5:00 of Mercury is? I'm not finding what you are referring to. All I see is haze and trees all around both Mercury and Venus. How close to Mercury is it? It’s about an inch below and to the right of Mercury as it first bec...

Tszabeau wrote: ↑Fri May 29, 2020 2:17 pm Does anyone know what the object, visible in the full sized view, at approx. 5:00 of Mercury is?

I'm not finding what you are referring to. All I see is haze and trees all around both Mercury and Venus. How close to Mercury is it?

The amount of light that is reflected off a still water surface depends on the angle of incidence. Taking that to be about 45° here, and solving the Fresnel equation, puts the reflected intensity at about 5%. Photographically, that means there is more than a 4-stop difference between the intensity ...

Orin, that's mysterious the disappearing clouds. My guess is though that the clarity is less in the reflection is that the water is dimmer so the photographer had to ramp the exposure f-stop up thereby making the sky look overexposed. By the way compliments to Helmut the photographer, I find this c...

NCTom wrote: ↑Sun May 24, 2020 11:55 am That was some crack considering after a couple of billion years of dust storms the thing is still 8 kilometers deep!

Hmm, that's an interesting thought. I wonder if the canyon really does have a very thick layer of dust at its bottom...

orin stepanek wrote: ↑Sun May 24, 2020 11:30 am marsglobe_viking_960.jpg

So big that the best view is from afar!

Perhaps, but it would sure be sweet to be able to fly along and within it in a helicopter!

... Meteors or satellites? The description starts with "Stars shine and satellites glint"... Yes, I see three "streaks" in the image. Two bright ones, and one fainter one nearer the LMC (visible in the linked higher-res image). And now that you've pointed out that one that I mis...

https://apod.nasa.gov/apod/calendar/S_200523.jpg Ghost Fungus to Magellanic Cloud Explanation: Stars shine and satellites glint in this clear, dark, night sky over Wannon Falls Reserve, South West Victoria, Australia. In fact the fuzzy, faint apparition above the tree tops is the only cloud visible...

What could possibly be the survival advantage of bioluminescence for a fungal organism? That's a very interesting question. The best answer I found is in a thread here - https://worldbuilding.stackexchange.com/questions/565/what-would-be-the-evolutionary-advantage-for-plants-to-be-bioluminescent. T...

orin stepanek wrote: ↑Sat May 23, 2020 12:09 pm IMG_1478-Edit1200.jpg

Yes The SMC is there; also a couple of meteor streaks
as well!
I loved the Silhouette of the large tree also!

Meteors or satellites? The description starts with "Stars shine and satellites glint"...

Hmm. I note that all these crescents are horizontal. Does that mean something particular about where the pictures were taken on the Earth? Is a horizontal crescent mandatory (or even possible) for an inferior planet when viewed from Earth? Or was this just depicted this way for artistic effect? Sor...

Hmm. I note that all these crescents are horizontal. Does that mean something particular about where the pictures were taken on the Earth? Is a horizontal crescent mandatory (or even possible) for an inferior planet when viewed from Earth? Or was this just depicted this way for artistic effect? Sorr...

I pity the fool who prints out the poster of Uranus or Neptune!

Also, it's a crying shame that the posters for the different versions of "asteroids", "comets" and "beyond" don't indicate what particular object they are pictures of

I often wonder when viewing simulations like this - just how fast is the viewer apparently moving? I have to guess it would be many times the speed of light. Yes, warp 7, in fact. So we only travel 7 3 = 343 light minutes over the minute of video :?: Clearly, it's much faster than that. Assuming we...

I agree with others who have said that a weather phenomenon is not a topic of astronomy. Years ago I submitted a photo of an analemmatic sundial that I constructed. It was rejected by the editors of APOD. You would think that a sundial has much more to do with astronomy than a waterspout. Would you...

Explanation: ....Their last go-round lasted about 100 million years.... Just curious how they could know such a detail? And if just their last interaction lasted that long (presumably when they were closest?), and these two galaxies are gradually spiraling toward each other, I would think it would ...

Amazing that such a clear image was taken from the earth. Also, I guess the great red spot was not in view for this picture (else I would think it would show up as a round feature of some sort)?