4 ms·

Oh, interesting! Wouldn't it be easier to photograph our own? :-)

by pjungwir 8y ago

losteric 8y ago
Nope, for the same reason we had photos of the Moon before we had photos of Earth.
- nazgul17 8y ago
  Can you expand on this?
  - CydeWeys 8y ago
    What they're saying is that we had to send a camera away from the Earth (in a rocket) in order to photograph it properly, and similarly you'd need to send a camera away from our galaxy (in a biiiig rocket) in order to be able to photograph it properly.
    - deleted 8y ago
      [deleted]
jug 8y ago
During the press conference, they said photographing the M87 black hole was like shooting a hibernating bear, and photographing the Sag A* black hole of our galaxy like photographing a quickly moving toddler. Something about the speed making it much harder. It is also much smaller, but that's less of a problem because it's much closer. All in all apparently making it about the same angular size. But it sounds like they'll get to it, it's just harder.
- SamBam 8y ago
  That's a... weird analogy.
  - salthound 8y ago
    I think the actual analogy was lost in translation: the point is that, unlike its older brother, Sgr A* is not going to "pose" when you point your camera at it.
    - SamBam 8y ago
      Ah, I thought it was about actually shooting bears and toddlers.
codethief 8y ago
Actually not. M87 is a 1000 times farther away than Sgr A* but also a 1000 heavier and thus a 1000 times bigger in diameter. (Diameter/radius scale proportionally with the black hole's mass.) Therefore, the actual angular size on our night sky is the same for both black holes and, from this point of view, both would be equally difficult to observe. However, as they mention in the press conference, Sgr A* moves a lot faster relative to us than M87, so it's much harder to take a still image. (In the press conference they used the example of trying to take a photo of a toddler with an exposure time of 8 hours.)
hannasanarion 8y ago
M87's black hole is currently eating something big, which makes it brighter. The black hole at the center of the milky way doesn't seem to have eaten anything lately, so it's accretion disk may be small or nonexistent.
- schlowmo 8y ago
  > is currently eating something big You mean: was eating something big 55 million years ago ;)
CydeWeys 8y ago
Nope. The view of our own galaxy's supermassive black hole is completely obstructed by matter within our own galaxy. You can't see to the core of our galaxy; it's too dense. You'd have to send a rocket quite some distance outside of the galactic plane to get a good view of it.
- nwallin 8y ago
  The images are made with radio telescopes, which cuts through the dust quite easily. We have many other radio observations of Sagittarius A* [1], albeit at much lower resolutions. There are also numerous observations of Sagittarius A* in X-ray wavelengths, which is also fine because they are so energetic they simply punch through. All the dust and gas in the galaxy is transparent at most wavelengths except the visible one. The Event Horizon Telescope is interesting because it is, in essence, a radio telescope that uses a "sensor" that is the size of the entire Earth. As such, it is able to make much higher resolution observations. [1] https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:Cloudlets_swarm_around_our_local_supermassive_black_hole.tif https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:Clo... [2] https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:X-RayFlare-BlackHole-MilkyWay-20140105.jpg https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:X-R...

Oh, interesting! Wouldn't it be easier to photograph our own? :-)

losteric 8y ago

Nope, for the same reason we had photos of the Moon before we had photos of Earth.

nazgul17 8y ago
Can you expand on this?
- CydeWeys 8y ago
  What they're saying is that we had to send a camera away from the Earth (in a rocket) in order to photograph it properly, and similarly you'd need to send a camera away from our galaxy (in a biiiig rocket) in order to be able to photograph it properly.
  - deleted 8y ago
    [deleted]

jug 8y ago

During the press conference, they said photographing the M87 black hole was like shooting a hibernating bear, and photographing the Sag A* black hole of our galaxy like photographing a quickly moving toddler. Something about the speed making it much harder. It is also much smaller, but that's less of a problem because it's much closer. All in all apparently making it about the same angular size. But it sounds like they'll get to it, it's just harder.

SamBam 8y ago
That's a... weird analogy.
- salthound 8y ago
  I think the actual analogy was lost in translation: the point is that, unlike its older brother, Sgr A* is not going to "pose" when you point your camera at it.
  - SamBam 8y ago
    Ah, I thought it was about actually shooting bears and toddlers.

codethief 8y ago

Actually not. M87 is a 1000 times farther away than Sgr A* but also a 1000 heavier and thus a 1000 times bigger in diameter. (Diameter/radius scale proportionally with the black hole's mass.) Therefore, the actual angular size on our night sky is the same for both black holes and, from this point of view, both would be equally difficult to observe. However, as they mention in the press conference, Sgr A* moves a lot faster relative to us than M87, so it's much harder to take a still image. (In the press conference they used the example of trying to take a photo of a toddler with an exposure time of 8 hours.)

hannasanarion 8y ago

M87's black hole is currently eating something big, which makes it brighter. The black hole at the center of the milky way doesn't seem to have eaten anything lately, so it's accretion disk may be small or nonexistent.

schlowmo 8y ago
> is currently eating something big You mean: was eating something big 55 million years ago ;)

CydeWeys 8y ago

Nope. The view of our own galaxy's supermassive black hole is completely obstructed by matter within our own galaxy. You can't see to the core of our galaxy; it's too dense. You'd have to send a rocket quite some distance outside of the galactic plane to get a good view of it.

nwallin 8y ago
The images are made with radio telescopes, which cuts through the dust quite easily. We have many other radio observations of Sagittarius A* [1], albeit at much lower resolutions. There are also numerous observations of Sagittarius A* in X-ray wavelengths, which is also fine because they are so energetic they simply punch through. All the dust and gas in the galaxy is transparent at most wavelengths except the visible one. The Event Horizon Telescope is interesting because it is, in essence, a radio telescope that uses a "sensor" that is the size of the entire Earth. As such, it is able to make much higher resolution observations. [1] https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:Cloudlets_swarm_around_our_local_supermassive_black_hole.tif https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:Clo... [2] https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:X-RayFlare-BlackHole-MilkyWay-20140105.jpg https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:X-R...