Starship Asterisk*

[quote=raschumacher post_id=340762 time=1723476472]
[quote=johnnydeep post_id=340743 time=1723397988 user_id=132061]
"Bots"? What bots? (I ain't no dang bot!)
[/quote]
That's just what a bot *would* say! :_>

(I meant, of course, the bots which the "Submit" puzzles are designed to foil, and not your most hu-man admirable self.)
[/quote]

Hmm. "Submit puzzles"? You mean that you are presented with a puzzle to solve correctly when using the "Submit" button to submit a post here? If so, I never see that... perhaps because I've created an assount?

[quote=johnnydeep post_id=340743 time=1723397988 user_id=132061]
"Bots"? What bots? (I ain't no dang bot!)
[/quote]
That's just what a bot *would* say! :_>

(I meant, of course, the bots which the "Submit" puzzles are designed to foil, and not your most hu-man admirable self.)

[quote="Uli Bastian" post_id=340759 time=1723470262]
Concerning the fact that the animated orbit INDEED is retrograde:
Thanks, I got the point. It is, indeed. Very nice. In order to avoid my misunderstanding with other people, it might be considered to change the start-up viewing perspective of the animation. If you make the start-up view perpendicular to the ecliptic (i.e. with the Earth orbit appearing as a near-perfect circle), the meteoroid cloud looks equally nice, and the retrograde orbit - as well as the velocity of the meteoroids wrt the Earth - become unambiguous.
:)
[/quote]

Yes, the default viewing orientation creates the illusion that the orbital plane of the debris lies on the ecliptic. Another useful trick is to color the particles according to whether they are above or below the ecliptic.

Concerning the fact that the animated orbit INDEED is retrograde:
Thanks, I got the point. It is, indeed. Very nice. In order to avoid my misunderstanding with other people, it might be considered to change the start-up viewing perspective of the animation. If you make the start-up view perpendicular to the ecliptic (i.e. with the Earth orbit appearing as a near-perfect circle), the meteoroid cloud looks equally nice, and the retrograde orbit - as well as the velocity of the meteoroids wrt the Earth - become unambiguous.
:)

[quote=raschumacher post_id=340742 time=1723391751]
[And, dang. Them bots is gettin' smart.]
[/quote]

"Bots"? What bots? (I ain't no dang bot!)

[And, dang. Them bots is gettin' smart.]

[quote=johnnydeep post_id=340739 time=1723381692 user_id=132061]
I've got nothing to say about astronomy or this APOD other than to remark how impressive doing this animation in a web page is to me.
[/quote]

Agreed, it's brilliant. Now if only it included a date indicator...

[quote="Uli Bastian" post_id=340738 time=1723359623]
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.
[/quote]

Their orbit [i]is [/i]retrograde. It's just a little hard to see since their orbital plane is nearly perpendicular to Earth's. Tilt the viewing angle and look closely.

I've got nothing to say about astronomy or this APOD other than to remark how impressive doing this animation in a web page is to me. I suppose it's all done with JavaScript that the browser is running? My limited page analysis tools show this:


[attachment=0]perseids animation.jpg[/attachment]

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.

[url=https://apod.nasa.gov/apod/ap240811.html] [img]https://apod.nasa.gov/apod/calendar/S_240811.jpg[/img] [size=150]Animation: Perseid Meteor Shower[/size][/url]

[b] Explanation: [/b] Where do Perseid meteors come from? Mostly small bits of stony grit, [url=https://science.nasa.gov/solar-system/meteors-meteorites/perseids/]Perseid meteoroids[/url] were once expelled from [url=https://en.wikipedia.org/wiki/Comet_Swift%E2%80%93Tuttle]Comet Swift-Tuttle[/url] and continue to follow this comet's orbit as they slowly disperse. The [url=https://www.meteorshowers.org/view/Perseids]featured animation[/url] depicts the entire meteoroid stream as it orbits [url=https://science.nasa.gov/sun/]our Sun[/url]. When the Earth nears this stream, as it does every year, the [url=https://en.wikipedia.org/wiki/Perseids]Perseid Meteor Shower[/url] occurs. Highlighted as bright in the animation, [url=https://apod.nasa.gov/apod/ap240106.html]comet debris[/url] this size is usually so dim it is practically undetectable. Only a small fraction of this debris will enter the [url=https://www.nasa.gov/general/what-is-earths-atmosphere/]Earth's atmosphere[/url], heat up and [url=https://apod.nasa.gov/apod/ap011118.html]disintegrate brightly[/url]. Tonight and the next few nights promise some of the better skies to view the [url=https://apod.nasa.gov/apod/ap170818.html]Perseid shower[/url] as well as [url=http://cams.seti.org/FDL/]other active showers[/url] because the [url=https://moon.nasa.gov/resources/54/phases-of-the-moon/]first quarter moon[/url] will be [url=https://www.reddit.com/r/FindTheSniper/comments/1chffk6/find_the_cat/]absent[/url] from [url=https://science.nasa.gov/skywatching/whats-up/]the sky[/url] from [url=https://earthsky.org/astronomy-essentials/everything-you-need-to-know-perseid-meteor-shower/]midnight onward[/url].


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