Search found 1564 matches

by JohnD
Wed Sep 29, 2021 6:18 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Gigantic Jet Lightning from Puerto Rico (2021 Sep 29)
Replies: 13
Views: 3038

Re: APOD: Gigantic Jet Lightning from Puerto Rico (2021 Sep 29)

Neufer,
thnak you, I think I shall put fulgura frango on my race car!
by JohnD
Wed Sep 29, 2021 8:37 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Gigantic Jet Lightning from Puerto Rico (2021 Sep 29)
Replies: 13
Views: 3038

Re: APOD: Gigantic Jet Lightning from Puerto Rico (2021 Sep 29)

70km in one second is slower than a lightning stroke, which goes about 70 MILES in one second.
But I suppose this is going upwards so fighting gravity all the way!

JOhn
by JohnD
Thu Sep 16, 2021 5:11 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Mars Panorama 360 from Curiosity (2021 Sep 14)
Replies: 24
Views: 5746

Re: APOD: Mars Panorama 360 from Curiosity (2021 Sep 14)

Thank you, Johnnydeep! I can accept a lake in Gale Crater, and sediment on the lower flanks of Mount Sharpe. The Wiki entry on Gale includes, "An unusual feature of Gale is an enormous mound of "sedimentary debris" around its central peak, officially named Aeolis Mons (popularly known...
by JohnD
Thu Sep 16, 2021 9:26 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Mars Panorama 360 from Curiosity (2021 Sep 14)
Replies: 24
Views: 5746

Re: APOD: Mars Panorama 360 from Curiosity (2021 Sep 14)

Thank you, Chris, and Johnnydeep! Although I still can't see how "where now there is a mountain, there once was a lake..... the lake may have only been a few meters deep, just enough to form those sandstone deltas and thin layers of mud. But fluctuations in the water supply or the climate allow...
by JohnD
Wed Sep 15, 2021 11:00 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Cyclone Paths on Planet Earth (2021 Sep 15)
Replies: 26
Views: 14763

Re: APOD: Cyclone Paths on Planet Earth (2021 Sep 15)

Quote, " cyclones usually occur over water, which makes sense since evaporating warm water gives them energy. " Elementary mistake, surely? CONDENSING vapour provides the typhoon's energy. Or am I too picky, the water vapour has to be evaporated first, which occurs in tropical regions, the...
by JohnD
Tue Sep 14, 2021 11:13 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Mars Panorama 360 from Curiosity (2021 Sep 14)
Replies: 24
Views: 5746

Re: APOD: Mars Panorama 360 from Curiosity (2021 Sep 14)

The Mars Rovers' pictures and capabilities are always amazing, I love to see them! But feed my ignorance, please. Why is a "hill" a "Notch"? A notch is a groove or indentation, not a raised hummock. And why is Curiosity climbing Mount Sharp, "for clues about ancient water&qu...
by JohnD
Wed Sep 08, 2021 10:12 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Deep Sky Toward Andromeda (2021 Sep 08)
Replies: 29
Views: 7416

Re: APOD: The Deep Sky Toward Andromeda (2021 Sep 08)

Thank you, Ann, for your labelled version of this picture! Without it I was confused. But what a strange image! That red network seems to lie behind the galaxies, and that we are seeing the Energy Grid that lies between this and the next Universe, as in the Culture series of stories, by Sun-Earther ...
by JohnD
Sun Sep 05, 2021 9:34 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Earth and Moon (2021 Sep 05)
Replies: 20
Views: 6875

Re: APOD: Earth and Moon (2021 Sep 05)

Serendipitously, this somewhat bland if historic video was automatically followed by one as short, "Descent torwads Bennu", and subsequently by two more from NASA on the later stages of the still incomplete Osiris-Rex mission. Definitely worth following, IMHO! Roll on September 2023!
by JohnD
Wed Sep 01, 2021 11:15 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Dancing Ghosts: Curved Jets from... (2021 Sep 01)
Replies: 7
Views: 2108

Re: APOD: Dancing Ghosts: Curved Jets from... (2021 Sep 01)

Could the BHs emitting those jets be tumbling, precessing, so that instead of a straight jet along the axis, the direction varied with time?
This is happening to V404 Cygni : https://earthsky.org/space/black-hole-v ... rby-space/
by JohnD
Sun Aug 29, 2021 4:34 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Solar System Ball Drop (2021 Aug 25)
Replies: 38
Views: 102036

Re: JohnD wants to be our Playtex salesman?

Aren't some web searchers weird? To check quickly, I entered "moon feather hammer", not into my usual (couldn't be &rs%d to get that out) and the first entry was "Love Honey Fetish Selection. See Our Latest Fetish Wear." !?!?!? Web searchs use algorithms optimized to the use...
by JohnD
Thu Aug 26, 2021 9:02 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Solar System Ball Drop (2021 Aug 25)
Replies: 38
Views: 102036

Re: APOD: Solar System Ball Drop (2021 Aug 25)

Hmm. When I put that search into Google I got the expected Apollo video at the top of the list. Google structures its search results based on what it thinks your interests are. So the question is... what else have you been searching for lately? Why would I want to do that, when I have this lady at ...
by JohnD
Wed Aug 25, 2021 10:25 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Solar System Ball Drop (2021 Aug 25)
Replies: 38
Views: 102036

Re: APOD: Solar System Ball Drop (2021 Aug 25)

ta152h20, No, it was David Scott. Aren't some web searchers weird? To check quickly, I entered "moon feather hammer", not into my usual (couldn't be &rs%d to get that out) and the first entry was "Love Honey Fetish Selection. See Our Latest Fetish Wear." !?!?!? John Hmm. Whe...
by JohnD
Wed Aug 25, 2021 5:50 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Solar System Ball Drop (2021 Aug 25)
Replies: 38
Views: 102036

Re: APOD: Solar System Ball Drop (2021 Aug 25)

ta152h20,
No, it was David Scott.

Aren't some web searchers weird? To check quickly, I entered "moon feather hammer", not into my usual (couldn't be &rs%d to get that out) and the first entry was "Love Honey Fetish Selection. See Our Latest Fetish Wear." !?!?!?

John
by JohnD
Wed Aug 25, 2021 5:34 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Solar System Ball Drop (2021 Aug 25)
Replies: 38
Views: 102036

Re: APOD: Solar System Ball Drop (2021 Aug 25)

"The energy released by "landing on" is determined by the velocity of impact." Surely, 'times the mass of the object', Johnny? I'll bet that David Scott's hammer made a bigger hole in the moon dust than the feather! Same velocity, more energy. John PS Fred, your links seem out of...
by JohnD
Wed Aug 25, 2021 2:33 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Solar System Ball Drop (2021 Aug 25)
Replies: 38
Views: 102036

Re: APOD: Solar System Ball Drop (2021 Aug 25)

Does the slower fall speed make it safer for a person to fall that distance? You will note, if you watched the video, that even onto Ceres that has the lowest g used, the terminal velocity was 90kph, or 55mph. All others were in hundreds of kph. Since your falling astronaut will lack the security o...
by JohnD
Wed Aug 25, 2021 8:53 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Solar System Ball Drop (2021 Aug 25)
Replies: 38
Views: 102036

Re: APOD: Solar System Ball Drop (2021 Aug 25)

Does the slower fall speed make it safer for a person to fall that distance? SC, You will note, if you watched the video, that even onto Ceres that has the lowest g used, the terminal velocity was 90kph, or 55mph. All others were in hundreds of kph. Since your falling astronaut will lack the securi...
by JohnD
Tue Aug 24, 2021 8:28 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Abell 3827: Cannibal Cluster Lens... (2021 Aug 23)
Replies: 25
Views: 9868

Re: APOD: Abell 3827: Cannibal Cluster Lens... (2021 Aug 23)

Thnak you, All, especially Ann and Chris! I'm glad I asked the question, about colours and distance, because as I have said before, and IMHO of course, this should be a site with a scientific emphasis, where we can marvel at the beauty that is in astronomical science. The 'retouching' of star pictur...
by JohnD
Mon Aug 23, 2021 11:08 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Abell 3827: Cannibal Cluster Lens... (2021 Aug 23)
Replies: 25
Views: 9868

Re: APOD: Abell 3827: Cannibal Cluster Lens... (2021 Aug 23)

Today's blurb seems fixated on explaining gravitational lensing, and does so well, but at the expense of explaning the picture. For those who are unfamiliar with "Abell 3827", like me, it is the four bright objects near the centre. A link to, say, the Wiki entry would help: https://en.wiki...
by JohnD
Tue Aug 17, 2021 2:23 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: M57: The Ring Nebula from Hubble (2021 Aug 17)
Replies: 16
Views: 4016

Re: APOD: M57: The Ring Nebula from Hubble (2021 Aug 17)

Thank you, Ann and Chris! My next assignment is clear! Meanwhile, and if I may, isn't a photon a photon? For photons to have different energies, they will have different frequencies? Sure, near the star, an atom is more likely to receive a photon more frequently, perhaps leading to the doubly ionios...
by JohnD
Tue Aug 17, 2021 1:29 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: M57: The Ring Nebula from Hubble (2021 Aug 17)
Replies: 16
Views: 4016

Re: APOD: M57: The Ring Nebula from Hubble (2021 Aug 17)

Chris, OK, I imagined a simple explanation, and was wrong, but I can do complexity! You will be as short of time as any busy academic - please refer me to some source that will explain the mechanism? Neufer, Thank you! So the blue is due to Oxygen, not Helium? But why is that fluorescing near the st...
by JohnD
Tue Aug 17, 2021 9:53 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: M57: The Ring Nebula from Hubble (2021 Aug 17)
Replies: 16
Views: 4016

Re: APOD: M57: The Ring Nebula from Hubble (2021 Aug 17)

The intense spectrum of colours across the Ring Nebula represent the different elements being ionised and then fluorescing at a distinct frequnency and colour. So the spectrum represents a gradient of elements in the nebula that depends on their distance from the star. How does this gradient form? I...
by JohnD
Mon Aug 02, 2021 1:23 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Pluto in Enhanced Color (2021 Aug 01)
Replies: 15
Views: 4690

Re: APOD: Pluto in Enhanced Color (2021 Aug 01)

Good point, neufer! Nicely made! And lava tubes are a feature of both Earthly and Lunar geology. So, perhaps a coating of ice over a flowing river of water? BUT! Look at the shape of the Virgil Fossa as it approaches Elliot (click on my pic above for an enlarged version) The Fossae are jagged rifts,...
by JohnD
Mon Aug 02, 2021 11:03 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Pluto in Enhanced Color (2021 Aug 01)
Replies: 15
Views: 4690

Re: APOD: Pluto in Enhanced Color (2021 Aug 01)

Thank you, neufer, and Ann for the tutorial on cryovolcanism! But I repeat - there is no possibilty of liquid water on the surface of Pluto, or of amonia in liquid form, or methane either, when the appearance of the Virgil Fossae as it approaches Elliot resembles an eroded water channel. Ice II or I...