Search found 33 matches

by Antony Rawlinson
Mon Sep 26, 2022 8:56 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: All the Water on Planet Earth (2022 Sep 26)
Replies: 20
Views: 7823

Re: APOD: All the Water on Planet Earth (2022 Sep 26)

Can someone clarify why the ball representing "liquid fresh water" is so much larger than the one representing "all fresh-water lakes and rivers"? I thought at first that the difference must be held up in Arctic and Antarctic ice, but it's telling us "liquid fresh water".
by Antony Rawlinson
Mon Jul 25, 2022 6:20 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Find the New Moon (2022 Jul 25)
Replies: 29
Views: 12009

Re: APOD: Find the New Moon (2022 Jul 25)

An example of why we often use pseudocolor palettes when trying to get more out of an image. I've converted the original to grayscale and then applied a common pseudocolor mapping used for astronomical images. It results in an image that lets our eyes see more detail than would otherwise be apparen...
by Antony Rawlinson
Fri Dec 31, 2021 9:09 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: JWST on the Road to L2 (2021 Dec 31)
Replies: 27
Views: 8818

Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Can anyone explain whether space debris accumulates at the L-points and whether it could endanger the spacecraft? I originally understood the Webb to be targeted for an L-point along the line of the Earth's orbit, and thought in terms of Jupiter's "Trojan" and "Greek" asteroids -...
by Antony Rawlinson
Sun Jul 11, 2021 8:46 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Find the Moon (2021 Jul 11)
Replies: 9
Views: 3264

Re: APOD: Find the Moon (2021 Jul 11)

Oddly, the Moon's disk is quite large in the picture - but very faint. It took me a careful scan of the enlarged image to find it: just right of the frame centre. The lower limb, above the slight bulge in the skyline, is more obvious than the rest of the disk.
by Antony Rawlinson
Sun Jul 04, 2021 6:50 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Face on Mars (2021 Jul 04)
Replies: 12
Views: 3171

Re: APOD: The Face on Mars (2021 Jul 04)

Can anyone say where on the planet this is located?

Also what are the black dots that litter the frame? Are they surface features or just imaging effects?
by Antony Rawlinson
Mon Apr 12, 2021 8:09 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: When Black Holes Collide (2021 Apr 11)
Replies: 23
Views: 6744

Re: APOD: When Black Holes Collide (2021 Apr 11)

The text says it's computer-generated. Can anyone say what real-life scale it represents, in terms of distance/size, mass and time? I believe this is a simulation of stellar mass black holes colliding. So the black holes are several solar masses, and their event horizons several tens of kilometers ...
by Antony Rawlinson
Sun Apr 11, 2021 11:58 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: When Black Holes Collide (2021 Apr 11)
Replies: 23
Views: 6744

Re: APOD: When Black Holes Collide (2021 Apr 11)

The text says it's computer-generated. Can anyone say what real-life scale it represents, in terms of distance/size, mass and time? I believe this is a simulation of stellar mass black holes colliding. So the black holes are several solar masses, and their event horizons several tens of kilometers ...
by Antony Rawlinson
Sun Apr 11, 2021 8:18 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: When Black Holes Collide (2021 Apr 11)
Replies: 23
Views: 6744

Re: APOD: When Black Holes Collide (2021 Apr 11)

The text says it's computer-generated. Can anyone say what real-life scale it represents, in terms of distance/size, mass and time?
by Antony Rawlinson
Mon Apr 06, 2020 5:33 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: NGC 1672: Barred Spiral Galaxy from... (2020 Apr 06)
Replies: 16
Views: 3956

Re: APOD: NGC 1672: Barred Spiral Galaxy from... (2020 Apr 06)

I don't see any "bar". What I do see is an asymmetric centre, with more bright material in the upper part (as seen in the image) of the central swirl than in the lower. What am I supposed to be looking for?
by Antony Rawlinson
Tue Feb 25, 2020 8:17 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Jupiter's Magnetic Field from Juno (2020 Feb 25)
Replies: 16
Views: 6548

Re: APOD: Jupiter's Magnetic Field from Juno (2020 Feb 25)

Intriguing. At first I thought it was suggesting that the Great Red Spot was the southern magnetic pole, but the text refers to the Great Blue Spot. Are they associated?
by Antony Rawlinson
Wed Jan 01, 2020 5:39 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Betelgeuse Imagined (2020 Jan 01)
Replies: 46
Views: 20312

Re: APOD: Betelgeuse Imagined (2020 Jan 01)

I've never seen a supernova myself (I was only six when the one in the Large Magellanic Cloud occurred), and I'd love to see something as impressive as a supernova as bright as the full Moon. It might put a handicap on other astronomical observations for the duration of the phenomenon. Can anyone s...
by Antony Rawlinson
Wed Jan 01, 2020 4:24 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Betelgeuse Imagined (2020 Jan 01)
Replies: 46
Views: 20312

Re: APOD: Betelgeuse Imagined (2020 Jan 01)

It depends what you're counting. If you're counting things , you start at one. If you're counting quantities (like time) you start at zero. Not in this case. The Christian Era (or "Common Era") started with the year 1, not the year 0 - which was not designated. This means that centuries -...
by Antony Rawlinson
Wed Jan 01, 2020 9:33 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Betelgeuse Imagined (2020 Jan 01)
Replies: 46
Views: 20312

Re: APOD: Betelgeuse Imagined (2020 Jan 01)

Much as I agree that the "new decade" stuff is misplaced, let's get back to the astrophysics. The main page says that the Betelgeuse supernova won't be a danger to us, but will "rival the full moon" in brightness. What it doesn't say is how long it will last. Wanting to know abou...
by Antony Rawlinson
Tue Oct 22, 2019 7:58 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Night Sky Reflections from the... (2019 Oct 22)
Replies: 10
Views: 6726

Re: APOD: Night Sky Reflections from the... (2019 Oct 22)

I read through the - informative as always - text below the image, expecting to find mention of the human figure in the centre, and the heavenly body s/he is apparently holding in their right hand. Somehow among the tour of the rest of the image content, this detail seems frustratingly to have been ...
by Antony Rawlinson
Tue Oct 08, 2019 6:55 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Horsehead Nebula (2019 Oct 06)
Replies: 17
Views: 8037

Re: APOD: The Horsehead Nebula (2019 Oct 06)

Does the red emission nebula that makes the Horsehead visible, have a name? Yes it does. IC 434 But note, I am just an interested layman. I could be wrong. Wait for confirmation from an authority. Thanks for the info - although IC 434 seems more like a catalogue number than a name. I was just a lit...
by Antony Rawlinson
Sun Oct 06, 2019 7:59 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Horsehead Nebula (2019 Oct 06)
Replies: 17
Views: 8037

Re: APOD: The Horsehead Nebula (2019 Oct 06)

Does the red emission nebula that makes the Horsehead visible, have a name?
by Antony Rawlinson
Tue Sep 17, 2019 6:39 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Water Vapor Discovered on Distant... (2019 Sep 17)
Replies: 17
Views: 6229

Re: APOD: Water Vapor Discovered on Distant... (2019 Sep 17)

"... unconfirmed sister planet ..."? Does that mean suspected to exist from actual observations, or added purely speculatively for the purposes of the artist's image?
by Antony Rawlinson
Mon May 20, 2019 6:20 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Planets of the Solar System: Tilts... (2019 May 20)
Replies: 17
Views: 7299

Re: APOD: Planets of the Solar System: Tilts... (2019 May 20)

Interested to see this, as I hadn't seen this information in such a form. What I've seen in TV programmes on cosmology, is that the collision that led to the formation of our Moon, also set Earth's rotational axis at 23.4 degrees - thus giving us our seasons. But this gives us the impression that ro...
by Antony Rawlinson
Mon May 06, 2019 7:24 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Virtual Flyby of the Whirlpool Galaxy (2019 May 06)
Replies: 30
Views: 17012

Re: APOD: Virtual Flyby of the Whirlpool Galaxy (2019 May 06)

This is disappointing in that the image of the galaxy remains a 2-D representation. When I read "virtual fly-by", I was kind of expecting it to reveal a 3-D structure - which of course I knew would have to be inferred rather than observed.
by Antony Rawlinson
Sun Dec 23, 2018 8:13 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Earthrise: A Video Reconstruction (2018 Dec 23)
Replies: 19
Views: 7141

Re: APOD: Earthrise: A Video Reconstruction (2018 Dec 23)

Why does it need to be a reconstruction? We can understand that the first time it happened, the Apollo crew were unprepared to film it, but the lunar mission continued for 10 more orbits of the moon, and there were further lunar missions, all with orbit modules. There was plenty of opportunity to fi...
by Antony Rawlinson
Wed Dec 19, 2018 12:36 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A Rainbow Geminid Meteor (2018 Dec 19)
Replies: 18
Views: 5398

Re: APOD: A Rainbow Geminid Meteor (2018 Dec 19)

The link purporting to show the start of the ionisation trail, under the text "can be seen" is a bit of a disappointment. Is it April 1?
by Antony Rawlinson
Fri Dec 14, 2018 11:50 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Swimming on Jupiter (2018 Dec 14)
Replies: 17
Views: 5413

Re: APOD: Swimming on Jupiter (2018 Dec 14)

Hitchhiker's Guide was right! The dolphins really did leave the Earth before it was demolished by the Vogons!
by Antony Rawlinson
Mon Jul 23, 2018 7:32 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Fermi Science Finals (2018 Jul 23)
Replies: 13
Views: 6876

Re: APOD: Fermi Science Finals (2018 Jul 23)

Are these actual telescopic images, false-colour enhancements, overlays of gamma images with visible light, or artists' impressions? The text doesn't make it clear.
by Antony Rawlinson
Sun Feb 11, 2018 8:29 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Roadster, Starman, Planet Earth (2018 Feb 10)
Replies: 40
Views: 59617

Re: APOD: Roadster, Starman, Planet Earth (2018 Feb 10)

Joules wrote:Is there a teapot in the trunk? https://en.wikipedia.org/wiki/Russell%27s_teapot
It'd be nice to finally get this Russell conundrum out of the way.
I already raised this point (with the link to Wikipedia). But to satisfy (or confound) Russell, it would need to be in free orbit IMO.
by Antony Rawlinson
Sat Feb 10, 2018 9:27 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Roadster, Starman, Planet Earth (2018 Feb 10)
Replies: 40
Views: 59617

Re: APOD: Roadster, Starman, Planet Earth (2018 Feb 10)

But this was a test firing, where the usual payload would have been blocks of concrete, Thanks for this explanation. I thought the world - or at least NASA - had gone mad. Why didn't they think of making Bertrand Russell's teapot https://en.wikipedia.org/wiki/Russell%27s_teapot a reality if they fe...