Search found 17353 matches

by Chris Peterson
Thu Apr 25, 2024 3:55 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: NGC 604: Giant Stellar Nursery (2024 Apr 25)
Replies: 7
Views: 312

Re: APOD: NGC 604: Giant Stellar Nursery (2024 Apr 25)

I'm still somewhat puzzled by JWST colour choices. Is there a scientific reason why they chose pink/red for NGC 604 but a kind of rusty brownish not-really-red for the Tarantula Nebula? Is it to reflect different molecular properties or are these different colours for no real reason? 604.png 2070.j...
by Chris Peterson
Thu Apr 25, 2024 2:54 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: NGC 604: Giant Stellar Nursery (2024 Apr 25)
Replies: 7
Views: 312

Re: APOD: NGC 604: Giant Stellar Nursery (2024 Apr 25)

I'm still somewhat puzzled by JWST colour choices. Is there a scientific reason why they chose pink/red for NGC 604 but a kind of rusty brownish not-really-red for the Tarantula Nebula? Is it to reflect different molecular properties or are these different colours for no real reason? 604.png 2070.j...
by Chris Peterson
Tue Apr 23, 2024 6:12 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Contrail Shadow X (2024 Apr 23)
Replies: 20
Views: 548

Re: APOD: Contrail Shadow X (2024 Apr 23)

P. Mitchell wrote: Tue Apr 23, 2024 6:08 pm These are not 'contrails'.
They are most certainly the condensation trails produced by passing jet airplanes. Contrails.
by Chris Peterson
Tue Apr 23, 2024 3:52 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Contrail Shadow X (2024 Apr 23)
Replies: 20
Views: 548

Re: APOD: Contrail Shadow X (2024 Apr 23)

from beneath https://www.globe.gov/documents/16792331/47233527/cld_pers1.jpg/f3c94d07-4a38-414c-b856-1566e7e7c5ae?t=1581356571539 Right... but relevance to my comments? ok I am fitting the shadow, the trails and Sun… and you are right, Sun is high in the sky Contrail Shadow X (2024 Apr 23)-.jpg I'm...
by Chris Peterson
Tue Apr 23, 2024 2:27 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Contrail Shadow X (2024 Apr 23)
Replies: 20
Views: 548

Re: APOD: Contrail Shadow X (2024 Apr 23)

I agree with others here that we are seeing the shadows of the contrails cast down onto the clouds, not up. (I'm not convinced it's even possible to have a contrail shadow cast up onto a cloud... the Sun would have to be on or slightly below the horizon, and I think the directly illuminated cloud w...
by Chris Peterson
Tue Apr 23, 2024 1:49 pm
Forum: The Observation Deck: Latest Sky Photography
Topic: Submissions: 2024 April
Replies: 91
Views: 3616

Re: Submissions: 2024 April

NGC 2403 This spiral galaxy in Camelopardalis is often compared to M33, but is imaged much less often. Visually, it is a bright binocular object. It is strikingly populated by H II regions, one of which is so large it has its own catalog designation (NGC 2404) inside its parent galaxy. NGC 2403 is ...
by Chris Peterson
Tue Apr 23, 2024 12:53 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Contrail Shadow X (2024 Apr 23)
Replies: 20
Views: 548

Re: APOD: Contrail Shadow X (2024 Apr 23)

I agree with others here that we are seeing the shadows of the contrails cast down onto the clouds, not up. (I'm not convinced it's even possible to have a contrail shadow cast up onto a cloud... the Sun would have to be on or slightly below the horizon, and I think the directly illuminated cloud wo...
by Chris Peterson
Mon Apr 22, 2024 3:26 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)
Replies: 6
Views: 384

Re: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Bartolo wrote: Mon Apr 22, 2024 1:54 pm How wide are Mt Etna's smoke rings?
Well, the image was made about 70km from Etna, so given the Moon is a half degree wide, the smoke rings are about 0.08 degrees, and must therefore be about 100 meters across.
by Chris Peterson
Sun Apr 21, 2024 4:31 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Perijove 16: Passing Jupiter (2024 Apr 21)
Replies: 15
Views: 500

Re: APOD: Perijove 16: Passing Jupiter (2024 Apr 21)

johnnydeep wrote: Sun Apr 21, 2024 4:25 pm Two questions about some info from the links:

1. Why does the Jove probe spin - stability I guess? But doesn't that negatively impact the ability to take pictures? And how fast is it spinning?
https://www.jpl.nasa.gov/news/press_kit ... pacecraft/
by Chris Peterson
Sun Apr 21, 2024 1:26 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Perijove 16: Passing Jupiter (2024 Apr 21)
Replies: 15
Views: 500

Re: APOD: Perijove 16: Passing Jupiter (2024 Apr 21)

saturnine wrote: Sun Apr 21, 2024 1:14 pm
Roy wrote: Sun Apr 21, 2024 12:55 pm Could really do better with the William Tell Overture instead of that squirrel music.
I think “Jupiter, the Bringer of Jollity” by Holst is quite appropriate.
Until you recognize that Holst was addressing astrology, not astronomy!
by Chris Peterson
Sun Apr 21, 2024 1:08 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Perijove 16: Passing Jupiter (2024 Apr 21)
Replies: 15
Views: 500

Re: APOD: Perijove 16: Passing Jupiter (2024 Apr 21)

1) it would have been nice to state the date rather than say it was the 16th pass…like that tells us anything. 2) on a personal note, I hate when people add music to space videos. Could really do better with the William Tell Overture instead of that squirrel music. The APODs focus on the “ oh, Wow!...
by Chris Peterson
Sun Apr 21, 2024 3:46 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Diamonds in the Sky (2024 Apr 20)
Replies: 13
Views: 555

Re: APOD: Diamonds in the Sky (2024 Apr 20)

Hey there, I'm the author of this composite. These images were captured with my lens on a star tracker in Arkansas. The camera was not level at the time of the exposures because I didn't make any adjustments to the camera during tracking by adjusting where the camera was on the right ascension axis...
by Chris Peterson
Sat Apr 20, 2024 3:50 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Diamonds in the Sky (2024 Apr 20)
Replies: 13
Views: 555

Re: APOD: Diamonds in the Sky (2024 Apr 20)

Alright, I'll ask: why aren't the two "diamonds" on the same line through the center of the eclipse? The centers of the Sun and Moon are coincident at totality, so why aren't the two diamond colinear with the center? The centers of the two bodies are only coincident at mid-totality if you...
by Chris Peterson
Thu Apr 18, 2024 6:02 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Total Eclipse and Comets (2024 Apr 17)
Replies: 25
Views: 1024

Re: APOD: Total Eclipse and Comets (2024 Apr 17)

But I suppose even if there are only two bodies in a system, like, say, the Sun and Jupiter, the Sun may - and will - change mass over time through its evolution along the Hertzsprung-Russell diagram due to changes in its nuclear fusion processes. So I'd think that could also eventually perturb Jup...
by Chris Peterson
Thu Apr 18, 2024 3:46 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Total Eclipse and Comets (2024 Apr 17)
Replies: 25
Views: 1024

Re: APOD: Total Eclipse and Comets (2024 Apr 17)

I wonder what makes the comet get too close to the Sun ? I'd imagine gravity pull .. but then, how long it must have taken that comet to reach that stage (i mean how many times it must have made rounds around Sun and how many years it must have been doing it before finally getting too close and get...
by Chris Peterson
Thu Apr 18, 2024 2:16 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Total Eclipse and Comets (2024 Apr 17)
Replies: 25
Views: 1024

Re: APOD: Total Eclipse and Comets (2024 Apr 17)

I wonder what makes the comet get too close to the Sun ? I'd imagine gravity pull .. but then, how long it must have taken that comet to reach that stage (i mean how many times it must have made rounds around Sun and how many years it must have been doing it before finally getting too close and get...
by Chris Peterson
Wed Apr 17, 2024 11:27 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Total Eclipse and Comets (2024 Apr 17)
Replies: 25
Views: 1024

Re: APOD: Total Eclipse and Comets (2024 Apr 17)

Superb image, particularly the corona which extends further than in many other images. That's right. But you should always be aware of the spatial conditions. It looks like the corona extends almost to Mercury. In reality, Mercury's orbit is still quite far away... https://live.staticflickr.com/655...
by Chris Peterson
Wed Apr 17, 2024 3:23 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Total Eclipse and Comets (2024 Apr 17)
Replies: 25
Views: 1024

Re: APOD: Total Eclipse and Comets (2024 Apr 17)

florid_snow wrote: Wed Apr 17, 2024 3:10 pm You missed the "Of these" reference at the start of the sentence. I think the writer was just trying to point out that the comets and Mercury were not visible to the unaided eye. But yes, Jupiter was bright! It must be just out of frame in this image.
Ah. Quite.
by Chris Peterson
Wed Apr 17, 2024 2:54 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Total Eclipse and Comets (2024 Apr 17)
Replies: 25
Views: 1024

Re: APOD: Total Eclipse and Comets (2024 Apr 17)

Also visible in the image is the sprawling corona of our Sun and the planets Mercury (left) and Venus (right). Of these planets and comets, only Venus was easily visible to millions of people in the dark shadow of the Moon that crossed North America on April 8. Huh? Jupiter was absolutely brilliant...
by Chris Peterson
Wed Apr 17, 2024 1:34 pm
Forum: Starship Asterisk: Handbook
Topic: Please help me
Replies: 1
Views: 363

Re: Please help me

Does anyone know of a way to display powerpoint slides from the Classroom directly on web pages, without having to download the entire PPT file Candy Crush ? I don't think you can. There are online PPT viewers if you don't have PowerPoint that let you view the slides in a browser, and you can use t...
by Chris Peterson
Tue Apr 16, 2024 6:29 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Cigar Galaxy from Hubble and Webb (2024 Apr 15)
Replies: 27
Views: 1322

Re: APOD: The Cigar Galaxy from Hubble and Webb (2024 Apr 15)

"shows, unexpectedly, that this red-glowing dust is associated with hot plasma." Is it unexpected because there is plasma inside stars, but this is plasma dust in between stars, as if chunks of plasma were blown out of stars? Plasma is just highly ionized gas. That is, a mix of neutral at...
by Chris Peterson
Tue Apr 16, 2024 1:20 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Colors of Twilight vs. Sunset/Sunrise
Replies: 26
Views: 1649

Re: Colors of Twilight vs. Sunset/Sunrise

I can see that the mixture of red and blue light in the sky under certain circumstances will make parts of even in the cloudless dawn or dusk sky look purple (because the atmosphere itself will reflect light and provide some mixing of the colors). I know I have seen clouds reflecting the dawn or du...
by Chris Peterson
Mon Apr 15, 2024 12:31 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: How a Total Solar Eclipse Ended (2024 Apr 14)
Replies: 12
Views: 859

Re: APOD: How a Total Solar Eclipse Ended (2024 Apr 14)

<r><QUOTE author="johnnydeep" post_id="338347" time="1713128783" user_id="132061"><s>[quote=johnnydeep post_id=338347 time=1713128783 user_id=132061]</s> <QUOTE author="Guest" post_id="338345" time="1713121809"><s>[quote=Guest post_id=338345 time=1713121809]</s> <QUOTE author="Chris Peterson" post_i...
by Chris Peterson
Sun Apr 14, 2024 6:56 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: How a Total Solar Eclipse Ended (2024 Apr 14)
Replies: 12
Views: 859

Re: APOD: How a Total Solar Eclipse Ended (2024 Apr 14)

I had seen several partials but never a total eclipse. I brought cameras along but after about 20 seconds I decided that I wasn't going to live this experience through the lens. There are countless other photographers more able than I to document this. I needed to see this in person and more import...
by Chris Peterson
Sun Apr 14, 2024 1:44 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: How a Total Solar Eclipse Ended (2024 Apr 14)
Replies: 12
Views: 859

Re: APOD: How a Total Solar Eclipse Ended (2024 Apr 14)

Once again, the digital sensors just plain maxed out as the sun re-emerged, while in person, the reappearance of the bright disk of the sun, while causing a person to avert their eyes from the brightness, was accompanied by a spotlight shaft of light shooting down from the sky into the circle of da...