Cientificamente falando...

[Hammerfall]

Citação de Lebohang, Em 12/01/2022 at 20:21:

“Há uma crise de corações em todo o mundo”: sete respostas para entender como o porco pode salvar milhares de pessoas

Bacon, costeletas, cozidos do crl... E agora isto.

Porco ❤️

[Ghelthon]

 

[bmfpcdm]

 

[bmfpcdm]

Citação de antifa, Em 14/09/2020 at 14:27:

Ora bem, é capaz de estar para rebentar uma coisa gigante.

Diz-se que existe um embargo de noticias, prestes a ser levantado, sobre uma descoberta no campo da astronomia, que levou a que um artigo da Nature até tivesse sido retirado. Trata-se da descoberta de fosfina na atmosfera de Vénus, um composto quimico associado à presença de vida, um subproduto da degradação do fosfato. Especula-se que não há as condições bioquimicas para ele existir no planeta Vénus sem a presença de vida, simplesmente não era suposto lá estar. A equipa que fez o estudo enviou-o há 6 meses para o MIT para especialistas testarem formas da molécula ser criada na ausência de vida e diz-se que não o conseguiram fazer.

Está agendada uma conferência de imprensa da Royal Astronomical Society para daqui a meia-hora que deverá tratar do tema:

 

 

[Ghelthon]

 

[Hammerfall]

Citação de Ghelthon, há 10 minutos:

 

Do subreddit de astronomia

Radio astronomer here!  It was clear this was was coming (I mean, why hold a giant press conference to announce you *still* don't have a picture of the black hole at the center of the Milky Way), but it's still so cool to see!!!

For those who want an overview, here is what's going on!

**What is this picture of?**

[Sagittarius A*](https://en.wikipedia.org/wiki/Sagittarius_A*) (Sgr A* for short) is the supermassive black hole (SMBH) at the center of our Milky Way, and weighs in at a whopping 4 million times the mass of the sun and is ~27,000 light years away from Earth (ie, it took light, the fastest thing there is, 27,000 light years to get here, and the light in this photo released today was emitted when our ancestors were in the Stone Age). We know it is a SMBH because it's incredibly well studied- in fact, [you can literally watch a movie of the stars orbiting it](https://galacticcenter.astro.ucla.edu/animations.html), and this won the teams studying it [the 2020 Nobel Prize in Physics](https://www.nobelprize.org/prizes/physics/2020/summary/).  So we knew Sag A* existed by studying the stars orbiting it (and even how much mass it had thanks to those orbits), but no telescope had enough resolution to see the black hole itself... until now!

Note, you cannot see Sag A* in our own night sky because of all the dust between us and it.  However, other wavelengths like infrared and radio can go straight through that dust even if visible light can't.

(Btw, it is called Sagittarius A* because in the early days of radio astronomy the brightest radio source in a constellation was called A, and at some point the * was added to denote a particularly radio bright part of Sagittarius A.  We're so creative with names in astro...) 

**Didn't we already have a picture of a black hole?  Why is this one such a big deal?**

We do!  That black hole is [M87*](https://en.wikipedia.org/wiki/Messier_87#Supermassive_black_hole_M87*), which is 7 billion times the mass of the sun (so over a thousand times bigger than Sag A\*) and is located 53 million light years from Earth.  It might sound strange that we saw this black hole first, but there were a few reasons for this that boil down to "it's way harder to get a good measurement of Sag A\* than M87\*."  First of all, it turns out there is a lot more noise towards the center of our galaxy than there is in the line of sight to a random one like M87- lots more *stuff* like [pulsars and magnetars](https://imagine.gsfc.nasa.gov/science/objects/neutron_stars1.html) and dust if you look towards the center of the Milky Way!  Second, it turns out Sag A* is far more variable on shorter time scales than M87\*- random stray dust falls onto Sag A* quite regularly, which complicates things.

As such, if you compare the old black hole pic vs this one, you'll see a lot more artifacts at the edge of this one's ring.  It's just tough to get a perfectly clear image in radio astronomy.

**I thought light can't escape a black hole/ things get sucked in!  How can we get a picture of one?**

Technically this picture is not *of* the black hole, but from a region surrounding it called the [event horizon](https://astronomy.swin.edu.au/cosmos/e/Event+Horizon).  This is the boundary that if light crosses when going towards the black hole, it can no longer escape.  However, if a photon of light is *just* at the right trajectory by the event horizon, [gravitational lensing](https://en.wikipedia.org/wiki/Gravitational_lens) from the massive black hole itself will cause those photons to bend around the event horizon!  As such, the photons never cross this important threshold, and are what we see in the image in this "ring."

Second, it's important to note that black holes don't "suck in" anything, any more than our sun is actively sucking in the planets orbiting it.  Put it this way, if our sun immediately became a black hole this very second, it would shrink to the size of just ~3 km (~2 miles), but nothing would change about the Earth's orbit!  Black holes have a bigger gravitational pull just because they are literally so massive, so I don't recommend getting close to one, but my point is it's not like a vacuum cleaner sucking everything up around it. (see [the video of the stars orbiting Sag A*](https://galacticcenter.astro.ucla.edu/animations.html) for proof).

**How was this picture taken?**

First of all, it is important to note this is *not* a picture in visible light, but rather one made of radio waves.  As such you are adding together the intensity from several individual radio telescopes and showing the intensity of light in 3D space and assigning a color to each intensity level. (I do this for my own research, with a much smaller radio telescope network.)

What makes this image particularly unique is it was made by a *very* special network of radio telescopes literally all around the world called the [Event Horizon Telescope \(EHT\)](https://eventhorizontelescope.org/)!  The EHT observes for a few days a year at 230–450 GHz simultaneously on telescopes ranging from Chile to Hawaii to France to the South Pole, then ships the data to MIT and the Max-Planck Institute in Germany for processing. (Yes, literally on disks, the data volume is too high to do via Internet... which means the South Pole data can be quite delayed compared to the other telescopes!) If it's not clear, co-adding data like this is *insanely* hard to do- I use telescopes like the [VLA](https://public.nrao.edu/telescopes/vla/) for my research, and that already gets filled with challenges in things like proper calibration- but if you manage to pull it off, it effectively gives you a telescope the size of the Earth!

To be completely clear, the EHT team is getting a very well-deserved Nobel Prize someday (or at least three leaders for it because that's the maximum that can get the prize- it really ought to be updated, but that's another rant for another day).  The only question is how soon it happens!

Also, the Event Horizon Telescope folks are giving an AMA on /r/askscience at 1:30pm-3:30pm (EDT) *today*! [link](https://www.reddit.com/r/askscience/comments/unyg77/askscience_ama_series_were_event_horizon/)  Definitely go over and ask them some questions I didn't cover here!  There is also a live public Q&A at 10:30am [here](https://www.youtube.com/watch?v=6TBX-K4Gu1Y), and [another livestreamed public Q&A panel](https://www.youtube.com/watch?v=imPzR6s2UM0) at 3pm EDT with some great colleagues from my institute- check it out!

**This is so cool- what's next?!**

Well, I have some good news and some bad news.  The bad news is we are not going to get a photo of another supermassive black hole for the foreseeable future, because M87* and Sag A* are the *only* two out there that are sufficiently large in angular resolution in the sky that you can resolve them from Earth (Sag A* because it's so close, M87* because it's a thousand times bigger than a Sag A* type SMBH, so you can resolve it in the sky even though it's millions of light years away).  You would need radio telescopes in space to increase the baselines to longer distance to resolve, say, the one at the center of the Andromeda Galaxy, and while I appreciate the optimism of Redditors insisting to me otherwise there are currently no plans to build radio telescopes in space in the coming decade or two at least.

However, I said there was good news!  First of all, the EHT can still get better resolution on a lot of stuff than any other telescope can and that's very valuable- for example, [here](https://upload.wikimedia.org/wikipedia/commons/6/61/EHTcentaurusA2021.jpg) is an image of a very radio bright SMBH, called Centaurus A, which shows better detail at the launch point of the jet than anything we've seen before.  Second, we are going to be seeing a *lot* in coming years in terms of variability in both M87* and Sag A\*!  Black holes are not static creatures that never change, and over the years the picture of what one looks like will change over months and years.  Right now, plans are underway to construct the [next generation Event Horizon Telescope \(ngEHT\)](https://www.ngeht.org/), which will build new telescopes just for EHT work to get even better resolution.  I recently saw a talk by [Shep Doeleman](https://en.wikipedia.org/wiki/Sheperd_S._Doeleman), the founding director of EHT, and he showed a simulation video of what it'll be like- basically you'll get snapshots of these black holes every few weeks/months, and be able to watch their evolution like a YouTube video to then run tests on things like general relativity.  *That* is going to be fantastic and I can't wait to see it!

**I have a question you didn't cover!**

Please ask it and I'll see if I can answer!  However, there are multiple ways to get your answer straight from a EHT scientist today and I encourage you to do that- those folks worked really hard and I know are excited to share the details after keeping their work secret for so long!

- EHT AMA on /r/askscience happening [here](https://www.reddit.com/r/askscience/comments/unyg77/askscience_ama_series_were_event_horizon/) from 1:30-3:30pm EDT (but you can post your question earlier)

- [A livestreamed public Q&A](https://www.youtube.com/watch?v=6TBX-K4Gu1Y) at 10:30am EDT.

- [Another livestreamed public Q&A](https://www.youtube.com/watch?v=imPzR6s2UM0) at 3pm EDT!

**TL;DR-** we now have a picture of the black hole at the center of the Milky Way.  Black holes are awesome!!!

Edit: Because people are asking, the James Webb Space Telescope (JWST) will not be able to do anything to this type of science either to add to it or observe the black hole itself.  First, it is not at the right wavelength of light, and second, it has nowhere near enough resolution to pull this off!

[Ghelthon]

Buracos negros são incrivelmente fascinantes.

[kareca]

 

[Ghelthon]

 

[SAS_Robben]

 

[Ghelthon]

Para contexto, a Terra é 3x maior que Mercúrio, portanto... Continua a ser tremendamente "unsettling".

[Eden Hazard]

Citação de SAS_Robben, há 10 horas:

 

fodase 

[Ghelthon]

Citação de Eden Hazard, há 1 minuto:

fodase 

 

[Stromp]

Pensar nisso, e consequentemente no tamanho da nossa galáxia e no tamanho das outras e no tamanho do Universo, dá-me dores de cabeça.

[Eden Hazard]

Citação de Stromp, há 11 minutos:

Pensar nisso, e consequentemente no tamanho da nossa galáxia e no tamanho das outras e no tamanho do Universo, dá-me dores de cabeça.

somos completamente irrelevantes à face do universo 

Editado 13 Junho 2022 por Eden Hazard

[SAS_Robben]

Vá, está na hora de nos reduzirmos a nossa insignificância.

[Ghelthon]

Em HD aqui: https://www.nasa.gov/sites/default/files/thumbnails/image/main_image_deep_field_smacs0723-5mb.jpg

Suponho que cada ponto de luz, dos que se vêem claramente àqueles que parecem meros píxeis, sejam galáxias.

(Mesmo incluindo gravitational lensing e tal.)

[Ghelthon]

 

[SAS_Robben]

Está é qualquer coisa.

Para quê inventar deuses quando o Universo já é de uma maravilha e magnitude infinitas?

Editado 12 Julho 2022 por SAS_Robben

[Rōnin]

❤️ 

[kareca]

este zoom

https://web.wwtassets.org/specials/2022/jwst-smacs/

[Che]

Citação de Rōnin, há 36 minutos:

❤️ 

Uma pessoa sabe que estas imagens é como aquelas fotos dos velhinhos em jovens que são mandadas colorir para pôr no cemitério, mas sim sr. Que obra de arte. 

[Hammerfall]

 

[Mayday]

 

[Ghelthon]

Citação de Mayday, Em 23/07/2022 at 18:22:

 

Isto não é falado na escola? Tenho ideia que sim.