Slashdot Mirror
Earth-Sized Telescope Set To Snap First Picture of a Black Hole (newscientist.com)
An anonymous reader writes from a New Scientist report: This week, we will have our first chance to take a picture of the supermassive black hole at the centre of our galaxy. The image could teach us how black holes work and even how the largest and smallest forces governing the universe fit together. The Event Horizon Telescope is switching on. It consists of eight radio observatories around the world, including telescopes in Spain, the US and Antarctica. And for just four or five nights between 5 and 14 April, if the weather is clear at all of the observatories, they will all turn on at once. Each telescope will point at Sagittarius A, the supermassive black hole at the centre of the Milky Way, and measure every radio wave coming from its direction. Linking together observatories spread across such a huge area and combining their observations to filter out extra light will effectively create a powerful "virtual telescope" almost the size of Earth. These telescopes will together capture sharper and more detailed data than we've ever had from Sagittarius A, which we still know very little about, as well as the larger black hole at the centre of nearby galaxy M87. With the telescopes generating a total of 2 petabytes of data per night -- enough to store the full genomes of some 2 billion people -- astronomers hope to take the first image of the event horizon around a black hole, and the bright matter hurtling around it.
Says, what's up doc?
https://www.youtube.com/watch?...
I have trouble with this "full genome" unit. Can you please express that in "football fields"?
OK, if you must, let's express that in metric units: it's about 1.6 x 10^-9 moles, or 1.6 nanomoles, of bytes.
Linking together observatories spread across such a huge area...
It is a symptom of humanity's hubris to believe that an area the size of Earth is considered huge when measuring the massive black hole that sits at the center of our galaxy.
How come Slashdot never gets Slashdotted?
enough to store the full genomes of some 2 billion people
There's a useless comparison. Unless you're doing a lot of genome storage I'd think that you'd have no idea what that means.
You only need to see the one object you're observing.
Ezekiel 23:20
Because the Earth is really flat. I knew it.
You can't, of course, "see" a black hole, even with radio waves: a black hole is by definition what you can't see.(*)
What they are looking to image is the radio emissions from material falling into the black hole. You can't see the black hole itself.
--
*footnote: Black holes do emit Hawking radiation, which in principle is detectable. But the peculiar property of Hawking radiation is that the smaller the black hole the more Hawking radiation. Only exceptionally tiny black holes emit enough to possibly detect-- a black hole ten micro meters across will emit just about the same amount of Hawking radiation as the microwave background.
http://www.geoffreylandis.com
There is no need for "at once".
Yes there is. You're thinking of parallax, but what they are doing is interferometry, so they will be comparing the phase of radio signals received on opposite sides of the globe. That has to be done simultaneously.
http://www.geoffreylandis.com
We are about to look at something you can't see?
That's not perfectly black. It's got a bunch of blue pixels randomly distributed across it.
Have gnu, will travel.
So, why do RADIO telescopes need to be concerned about the weather? I mean they look in the radio part of the spectrum and I would assume at the frequencies that aren't that affected by water vapor (or atmospheric gasses). So turbulence in the atmosphere wouldn't affect their performance (other than perhaps shaking the dish).
Is it because they are referring to electrical storms (lightning)? Or perhaps they are referring to "space" weather like solar flares and the ionosphere? (But I've never heard of those being an impediment to radio astronomy).
Anyway, just asking
I have trouble with this "full genome" unit.
Then you should have just read the preceding bit that tells you it is 2 petabytes - if that is any more meaningful to you
politicians are like babies' nappies: they should both be changed regularly and for the same reasons
What frequency goes through the milky way? Because that's where they have to look, for something black no less.
CLI paste? paste.pr0.tips!
It's Sagittarius A*, pronounced Sagittarius A-star.
I can see the sun right now. So can people in America.
Take a look at the map showing the locations of all the telescopes being used in this experiment. Notice that half of the world is not displayed? That isn't just because some monkey didn't crop the image correctly, it's because only half the world can see the same object at the same time.
For a practical demonstration note that you can see all locations of telescopes at the same time in this projection.
You don't have to dumb it down and say "virtual telescope". Call it what it is - an interferometer and make it a link so people who don't know the term can read about it and educate themselves.
Really cool link!
It's not a perfect imaging system.
My car gets forty rods to the hogshead and that's the way I likes it.
"Well, the thing about a black hole - its main distinguishing feature - is it's black. And the thing about space, the colour of space, your basic space colour, is black. So how are you supposed to see them?" - Holly, System AI, Jupiter Mining Corp. vessel Red Dwarf
Well then by the same logic you can't really see matter either. All you see is reflected photons.
Well, sure. But you see the photons reflected or emitted by the matter. On the other hand, you can't see photons reflected or emitted by a black hole, because black holes do not reflect or emit photons.
http://www.geoffreylandis.com
... At least I now know one person's genome information is 1TB
...which is genuinely interesting to me (though not relevant to the topic at hand).
I know right? I saw someone else show it on here a few months ago. Instant bookmark.