Search found 1092 matches
- Sun Jul 02, 2023 6:59 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: A Message from the Gravitational... (2023 Jun 29)
- Replies: 37
- Views: 6316
Re: APOD: A Message from the Gravitational... (2023 Jun 29)
The process of accretion involves accelerated mass. So it produces gravitational radiation. (Accretion always involves inspiraling matter.) It is the acceleration that matters. Spin a barbell and you produce gravitational radiation, despite the fact that the two masses remain at a fixed distance fr...
- Sat Jul 01, 2023 8:02 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Three Galaxies in Draco (2023 Jul 01)
- Replies: 14
- Views: 3064
Re: APOD: Three Galaxies in Draco (2023 Jul 01)
similar to astrometric images
- Fri Jun 30, 2023 4:56 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Orbits of Potentially Hazardous... (2023 Jun 30)
- Replies: 5
- Views: 1855
Re: APOD: Orbits of Potentially Hazardous... (2023 Jun 30)
Wow.. never imagined there's so many with their paths around Sun that close (relatively) to each other and all planets. We have decent idea about none of the PHA's (ones we have discovered/identified so far) colliding with Earth in next 100 years, I wonder, what's the probability of them hitting ot...
- Thu Jun 29, 2023 9:24 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: A Message from the Gravitational... (2023 Jun 29)
- Replies: 37
- Views: 6316
Re: APOD: A Message from the Gravitational... (2023 Jun 29)
2. Are these GWs directional, like the EM waves emitted by rotation or "lighthouse-like" pulsars that emit radiation along their spin axes? I don't know if there are any directional sources. But most are likely produced by two bodies, and the propagation is substantially on the plane of t...
- Thu Jun 29, 2023 7:03 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: A Message from the Gravitational... (2023 Jun 29)
- Replies: 37
- Views: 6316
Re: APOD: A Message from the Gravitational... (2023 Jun 29)
by the way we are lucky that gravity waves are polarized. If you try the same trick with sound waves, which are not polarized, you fail. Say you pick the acoustic noise in a room by subtracting signals at microphones A and B, then subtracting signals at microphones A and C, and hope to see a correla...
- Thu Jun 29, 2023 6:53 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: A Message from the Gravitational... (2023 Jun 29)
- Replies: 37
- Views: 6316
Re: APOD: A Message from the Gravitational... (2023 Jun 29)
those who learned that the CMB means the cosmic microwave background now face memorizing that the GWB means the gravitational wave background. No detailed map of distinct sources so far, just the total buzz amplitude of 2,4×10⁻¹⁵ at the frequencies about 1/year (that translates to 76 nanoseconds in ...
- Wed Jun 28, 2023 8:05 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Messier 24: Sagittarius Star Cloud (2023 Jun 28)
- Replies: 8
- Views: 2275
Re: APOD: Messier 24: Sagittarius Star Cloud (2023 Jun 28)
is there an IR view of M24 and Large Sgr with dust frames half-transparent?
showing how close they are to the disk and to the bulge of the Milky Way
showing how close they are to the disk and to the bulge of the Milky Way
- Tue Jun 27, 2023 5:15 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: MAVEN's Ultraviolet Mars (2023 Jun 27)
- Replies: 11
- Views: 3733
Re: APOD: MAVEN's Ultraviolet Mars (2023 Jun 27)
purple (technically, magenta). I agree that calling anti-green colour purple is outdated. Modern smartphones and even large monitors are no longer sRGB, they are UHDTV, which is closer to LMS cones of human retina. sRGB green was in fact lime-green, and so sRGB anti-green was in fact purple-pink. N...
- Tue Jun 27, 2023 2:23 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: MAVEN's Ultraviolet Mars (2023 Jun 27)
- Replies: 11
- Views: 3733
Re: APOD: MAVEN's Ultraviolet Mars (2023 Jun 27)
https://asterisk.apod.com/download/file.php?id=47758&t=1 MAVEN's Ultraviolet Mars Image Credit: MAVEN, Laboratory for Atmospheric and Space Physics, Univ. Colorado, NASA APOD Robot wrote: Recorded by the MAVEN spacecraft's Imaging Ultraviolet Spectrograph instrument in July 2022 (left) and Janu...
- Tue Jun 27, 2023 12:12 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: The Belt of Venus over Mount Everest (2023 Jun 26)
- Replies: 13
- Views: 3027
Re: APOD: The Belt of Venus over Mount Everest (2023 Jun 26)
https://asterisk.apod.com/download/file.php?id=47757&mode=view Wow; A lot of great photos in today's APOD Orin, that's a great image! :D I couldn't find it in the links of today's caption. Where did you find it? Anyway, Victor, I very much recommend the image posted by Orin, because it does a g...
- Mon Jun 26, 2023 12:05 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: The Belt of Venus over Mount Everest (2023 Jun 26)
- Replies: 13
- Views: 3027
Re: APOD: The Belt of Venus over Mount Everest (2023 Jun 26)
Let's try to make head or tails of the colors of today's APOD, shall we? https://apod.nasa.gov/apod/image/2306/BeltofEverest_Mukherjee_960_annotated.jpg Let's begin with the Earth's rising (or setting) shadow during sunset (or sunrise). Well, shadows in clear weather on the Earth tend to be blue, r...
- Sun Jun 25, 2023 4:39 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Lightning on Jupiter (2023 Jun 25)
- Replies: 13
- Views: 2947
Re: APOD: Lightning on Jupiter (2023 Jun 25)
I wonder why the flash looks yellow-green (lime) Keep in mind that JunoCam doesn't take a "snapshot", but has its sensor readout synchronized with the spacecraft rotation. So it takes about a minute to collect a single image (there are four filters) as one axis is swept out. What that mea...
- Sun Jun 25, 2023 4:35 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Lightning on Jupiter (2023 Jun 25)
- Replies: 13
- Views: 2947
Re: APOD: Lightning on Jupiter (2023 Jun 25)
Just a thought of why the lightning is green instead of electrical white. On Earth Auroras are usually photographed green and are from Solar winds descending the magnetic poles. Jupiter's magnetic fields are ten times stronger than Earth. And this is near Jupiter's north pole. Could this wide green...
- Sun Jun 25, 2023 4:32 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Lightning on Jupiter (2023 Jun 25)
- Replies: 13
- Views: 2947
Re: APOD: Lightning on Jupiter (2023 Jun 25)
if this lightning was thick hot plasma channel, then it should be the colour of blue giants: bluishguest again wrote: ↑Sun Jun 25, 2023 1:31 pm Green lightning, blue thunder?
- Sun Jun 25, 2023 10:13 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Lightning on Jupiter (2023 Jun 25)
- Replies: 13
- Views: 2947
Re: APOD: Lightning on Jupiter (2023 Jun 25)
I wonder why the flash looks yellow-green (lime)
- Sun Jun 25, 2023 10:06 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Giant Galaxies in Pavo (2023 Jun 23)
- Replies: 12
- Views: 3039
Re: APOD: Giant Galaxies in Pavo (2023 Jun 23)
Of course, in the end it is the amount of dark matter that determines which of these two massive galaxies, NGC 6872 or NGC 6876, is the most massive! Ann We have to use gravitation lensing to map the dark matter. JWST would see a lot of dim background galaxies… This little comma-thing in a pentagon...
- Sat Jun 24, 2023 5:38 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: 3D Ingenuity (2023 Jun 24)
- Replies: 6
- Views: 2250
Re: APOD: 3D Ingenuity (2023 Jun 24)
I wonder why do the solar power cells look uneven-coloured? What do you mean by "uneven-coloured"? It's a monochrome image. Do you mean that they aren't a uniform intensity? Could be dust, could just be seeing reflections from the surface. _ de-anaglyph-PIA24547.jpg Can't be reflection fr...
- Sat Jun 24, 2023 1:37 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: 3D Ingenuity (2023 Jun 24)
- Replies: 6
- Views: 2250
Re: APOD: 3D Ingenuity (2023 Jun 24)
I wonder why do the solar power cells look uneven-coloured?
- Sat Jun 24, 2023 1:35 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Giant Galaxies in Pavo (2023 Jun 23)
- Replies: 12
- Views: 3039
Re: APOD: Giant Galaxies in Pavo (2023 Jun 23)
...But I don't think the much smaller satellite galaxy IC 4970 has enough mass for that, even though there are two bright X-ray objects there. I would rather consider the huge NGC 6876 galaxy as the source... https://live.staticflickr.com/65535/52997744083_41e6450d4f_c.jpg biggg: https://live.stati...
- Fri Jun 23, 2023 5:30 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Giant Galaxies in Pavo (2023 Jun 23)
- Replies: 12
- Views: 3039
Re: APOD: Giant Galaxies in Pavo (2023 Jun 23)
My first thought looking at 2 arms, with straight long outer parts and curved-to-ring short inner parts: there was an explosion at the centre of the core, shooting out a pair of massive jets. The 2 jets left 2 star formation lanes. The differential rotation bended those lanes into spirals, but what ...
- Thu Jun 22, 2023 1:58 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: The Ñandú in the Milky Way (2023 Jun 20)
- Replies: 21
- Views: 4544
Re: APOD: The Ñandú in the Milky Way (2023 Jun 20)
https://apod.nasa.gov/apod/image/2306/NanduMilkyWay_Bouvier_1080.jpg Wow. Imagine having such dark skies that you can see the Coalsack as the head of an enormous cosmic bird! APOD Robot wrote: Pictured here is not only a segment of the central band of our Milky Way galaxy, but, according to folklor...
- Thu Jun 22, 2023 1:47 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: The Ñandú in the Milky Way (2023 Jun 20)
- Replies: 21
- Views: 4544
Re: APOD: The Ñandú in the Milky Way (2023 Jun 20)
Interesting. The indigenous peoples of Australia have a similar view of the emu in the sky - part of the creator spirits. The great river in the sky is where all the spirits reside. ? https://www.ayersrockresort.com.au/sites/default/files/2020-10/image002.jpg It's interesting that the indigenous pe...
- Mon Jun 19, 2023 10:51 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Saturn's Northern Hexagon (2023 Jun 18)
- Replies: 14
- Views: 4772
Re: APOD: Saturn's Northern Hexagon (2023 Jun 18)
"nowhere else in the galaxy" except here https://asterisk.apod.com/viewtopic.php?p=289252#p289252 NASA has also found a hexagon on Jupiter. https://www.jpl.nasa.gov/images/pia23559-jupiters-pentagon-turns-hexagon but no hexagon around the Noth pole, just a lightening on Dec. 30, 2020 http...
- Sun Jun 18, 2023 2:29 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Saturn's Northern Hexagon (2023 Jun 18)
- Replies: 14
- Views: 4772
Re: APOD: Saturn's Northern Hexagon (2023 Jun 18)
"nowhere else in the galaxy" except here https://asterisk.apod.com/viewtopic.php?p=289252#p289252 NASA has also found a hexagon on Jupiter. https://www.jpl.nasa.gov/images/pia23559-jupiters-pentagon-turns-hexagon but no hexagon around the Noth pole, just a lightening on Dec. 30, 2020 http...
- Fri Jun 16, 2023 3:36 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: M15: Dense Globular Star Cluster (2023 Jun 15)
- Replies: 16
- Views: 4907
Re: APOD: M15: Dense Globular Star Cluster (2023 Jun 15)
So would those central stars with "increasing velocities" be falling inward toward the black hole on a straight course, or circling in toward it in a spiral pattern? if toward the black hole on a straight course means passing at tidal rapture distance than the chances are zero. All they m...