Space space

LIGO Detects Fierce Collision of Neutron Stars for the First Time

LIGO Detects Fierce Collision of Neutron Stars for the First Time

Astronomer here! This is HUGE news! (TL;DR at bottom for those who just want the skinny.) There are two kinds of gravitational wave signal that LIGO can detect- colliding black holes (of which four such events have been found so far), and harder but a neutron star- neutron star (NS-NS) collision is also possible. And these are harder to detect, but the signal you get has a lot more going for it: first, no one knows for sure if black hole- black hole mergers even have any light they give off, but second the amount of sky you get from these LIGO signals if you want to do follow up is insane- you will literally get a map covering about half the sky and be told to go look. As you can imagine, that's not super useful.

NS-NS mergers, though, are different. First, we did expect them to give off electromagnetic radiation in some form- for example, there is a class of gamma ray burst (GRB), called short GRBs, which make up about 30% of all GRBs we detect but no one has said where they come from for sure but NS-NS mergers were the leading theory. It's been a mystery for decades though. Second, the map you get is way better on the sky- more like 30 square degrees (might not be perfectly remembering that number), which is still a lot of sky but nowhere near as bad as half of it if you want to find a counterpart.

So, in August, LIGO detected a gravitational wave from a NS-NS merger, and the gamma-ray telescope Fermi detected a GRB at the exact same time from that direction of sky. Moreover, it was astronomically pretty close to us- I don't remember how exactly you get distance from gravitational waves, but the point is you can and you could then make up a list of galaxies within that patch of sky within that distance for a short follow-up list. So this was way easier to track down, and everyone in August was laughing in astronomy because this was the worst kept secret of all time- all the big space telescopes have public logs, for example, when they do a "target of opportunity" it is public record. But what was found exactly was still a secret until today, and the answer is multiple telescopes picked up this signal in multiple bands, which is a kind of signal we've never seen before but some folks have literally spent decades looking for. So not only do we have the first successful follow up from a gravitational wave detector, we have solved the mystery of where 30% of GRBs come from AND witnessed a NS-NS merger for the first time ever!

On a final note, I should say that the first astronomer to discover the signal from this merger, in optical, is a colleague of mine who doesn't even normally focus on this stuff, but got lucky for doing follow up in the right place at the right time and thus gets the eternal fame and fortune. She is an awesome astronomer, plus all around good person, and it is always so lovely to see cool people succeed! :)

We are at the dawn of something new! This is an exciting place to be!

TL;DR- Not only did they discover the first ever neutron star-neutron star merger, they also did the first ever follow up in light to detect it there, and solved an enduring mystery lasting decades on where 30% of all gamma ray bursts come from. Pretty awesome day for science!

Edit: here's the paper for those curious

Well off the top of my head:

1) NS-NS mergers are where the far majority of heavy elements like gold and uranium are thought to be created. Huge to be able to study that

2) NS-NS mergers likely create black holes in many cases- we can actually study black holes being born!

3) It also proves that gravitational waves are going to be super important for finding these super rare astronomical events in the future

4) It solves the long-standing question of what creates short GRBs, which are some of the most energetic explosions we know of and are a third of all GRBs, but people haven't had proof of where they come from for decades.

I'm probably skipping some, but that's not a shabby starting list!

So what does this mean for the future of astronomy? What will astronomers gain from the knowledge gathered from this event?

... a blizzard of papers are being published, including one in The Astrophysical Journal Letters that has 4,500 authors — a third of all the professional astronomers in the world

Gotta love physics. Physicists out there, are the many papers in your field with tons of authors a reflection of the complexity and interconnectedness of the field? Or a strong spirit of giving everyone who contributed credit? Both?

The Great 1972 Daylight Fireball

The Great 1972 Daylight Fireball

It must have been awesome to witness. It was an earth-skimmer, so it had a long visible flight path and just went back out into space.

... like Chelyabinsk without the exploding and bleeding and whatnot

https://youtu.be/vBu-yUzWXqg

I believe there are 2 videos of the event 1 from Canada and another from the Grand Tetons... Here is restored video from the Grand Teton encounter ...

I saw this as a kid. We were in a campground, probably in southern Alberta. It looked like a fireball coming right at us. The fireball was amazing. It looked like special effects with layers of fire peeling off. My jaw was open. I could barely call out to my mom. I was dumbstruck. Where I was standing, the fireball seemed a bit bigger than the sun. The fireball passed right over head then disappeared over the horizon. I think everyone in the family did see it. My dad suggested that we should expect a large sound before too long. I don't recall if it arrived or not. I remember thinking that it probably hit "just over those mountains," and that we should drive to see it. My parents knew better.

I am Elon Musk, ask me anything about BFR!

I am Elon Musk, ask me anything about BFR!
I am Elon Musk, ask me anything about BFR!

Taking questions about SpaceX’s BFR. This AMA is a follow up to my IAC 2017 talk:

I can tell this thread is not for me.

We chickened out

Nerd

The engine thrust dropped roughly in proportion to the vehicle mass reduction from the first IAC talk. In order to be able to land the BF Ship with an engine failure at the worst possible moment, you have to have multiple engines. The difficulty of deep throttling an engine increases in a non-linear way, so 2:1 is fairly easy, but a deep 5:1 is very hard. Granularity is also a big factor. If you just have two engines that do everything, the engine complexity is much higher and, if one fails, you've lost half your power. Btw, we modified the BFS design since IAC to add a third medium area ratio Raptor engine partly for that reason (lose only 1/3 thrust in engine out) and allow landings with higher payload mass for the Earth to Earth transport function.

Elon Musk AMA in two hours!

Elon Musk AMA in two hours!

Remember that video where the audience is asking really stupid questions? Let's not have a repeat of that.

Alright, play it cool everybody. He'll be here to answer questions about BFR/ Mars. If you don't have a question about BFR or Mars missions, don't expect your question to be answered.

This. I felt so bad for Elon when he said he was saving technical questions for the Q&A, and was greeted by gibbering morons rather than industry guys.

"I WOULD LIKE TO WORK FOR YOU MISTER MUSK"

:cringggge:

SpaceX on Twitter - Falcon 9 first stage has landed on Of Course I Still Love You — third successful mission with a flight-proven orbital class rocket.

SpaceX on Twitter - Falcon 9 first stage has landed on Of Course I Still Love You — third success...

God I love how mundane this is getting. Can't wait for the BFR's flight tests down the line.

Thinking just that. How incredible is it that successfully completing a complex process such as this isn't headline newsworthy anymore because it's becoming routine. Not long ago this was either unimaginable, or fantastically impracticable. To think that's the price of progress - where we no longer feel awestruck at what used to be impossible.

Them damn used-rocket salesmen and their fancy vocabulary words!

Forgive me my ignorance, but "flight-proven" means re-used?

I just inherited this moon globe from my late Grandmother. The far side has a blank area as it was still unknown when the globe was made.

I just inherited this moon globe from my late Grandmother. The far side has a blank area as it was still unknown when the globe was made.
here's a diagram https://i.imgur.com/EDCoIDI.png

here's a diagram

Here's the more familiar side for most of you. I'm in Australia so it's upsidedown for me. I believe my grandparents bought it when they went on a trip to Canada and the USA. It also has a moon terrain stand. Here's a close up of the text and underside. Copyright says 1963, but the latest date I can find on there is Luna 9, Feb 3, 1966. It also has Surveyor marked, but its date format is different, it's marked as "2/6/66" (Rather than Month name, day, year in long format). 

So if I'm reading wikipedia right, Luna 3 had seen part of the far side, but not all of it by this point. 


On October 7, 1959, the Soviet probe Luna 3 took the first photographs of the lunar far side, eighteen of them resolvable,[12] covering one-third of the surface invisible from the Earth


In 1965 Zond 3 apparently took better pictures, but it was a soviet craft so the images may not have been seen before this was 
made?

(Edit: As some have mentioned, it seems like the map was made in 1963, and reprinted over a number of years with landing/crash sites of missions printed on latest stock as they happened. Also it has numbers for degrees around the equator. Looks like the missing part is about 60 degrees worth. Between 210 ans 270.)

And if you're wondering about the Ranger 4 impact site: 


An onboard computer failure caused failure of the deployment of the solar panels and navigation systems; as a result the spacecraft crashed on the far side of the Moon without returning any scientific data. It was the first spacecraft of the United States to reach another celestial body


I also got a globe that has the USSR on it. This one doesn't have a date so I'm unsure if it was purchased at the same time as the moon one.

. I'm in Australia so it's upsidedown for me. I believe my grandparents bought it when they went on a trip to Canada and the USA. It also has a moon terrain stand. Here's a close up of the text and underside. Copyright says 1963, but the latest date I can find on there is Luna 9, Feb 3, 1966. It also has Surveyor marked, but its date format is different, it's marked as "2/6/66" (Rather than Month name, day, year in long format).

So if I'm reading wikipedia right, Luna 3 had seen part of the far side, but not all of it by this point.

On October 7, 1959, the Soviet probe Luna 3 took the first photographs of the lunar far side, eighteen of them resolvable,[12] covering one-third of the surface invisible from the Earth

In 1965 Zond 3 apparently took better pictures, but it was a soviet craft so the images may not have been seen before this was made?

(Edit: As some have mentioned, it seems like the map was made in 1963, and reprinted over a number of years with landing/crash sites of missions printed on latest stock as they happened. Also it has numbers for degrees around the equator. Looks like the missing part is about 60 degrees worth. Between 210 ans 270.)

And if you're wondering about the Ranger 4 impact site:

An onboard computer failure caused failure of the deployment of the solar panels and navigation systems; as a result the spacecraft crashed on the far side of the Moon without returning any scientific data. It was the first spacecraft of the United States to reach another celestial body

I also got a globe that has the USSR on it. This one doesn't have a date so I'm unsure if it was purchased at the same time as the moon one.


I'm in Australia so it's upsidedown for me.


I don't understand this. 

Edit: Well I'll be damned! It really is flipped!

View of the moon from Australia.

View of the moon from England.

I'm in Australia so it's upsidedown for me.

I don't understand this.

Edit: Well I'll be damned! It really is flipped!

View of the moon from England.

Such a happy moon!

The Nobel Prize in Physics 2017 was divided, one half awarded to Rainer Weiss, the other half jointly to Barry C. Barish and Kip S. Thorne "for decisive contributions to the LIGO detector and the observation of gravitational waves"

The Nobel Prize in Physics 2017 was divided, one half awarded to Rainer Weiss, the other half jointly to Barry C. Barish and Kip S. Thorne "for decisive contributions to the LIGO detector and the observation of gravitational waves"
The Nobel Prize in Physics 2017 was divided, one half awarded to Rainer Weiss, the other half joi...

Interesting trivia: Kip Thorne was involved in the CGI work on the black hole in Interstellar as a scientific consultant.

To give you an idea of how crazy this is, Veritasium did a great video on it!

He co-authored this paper about accurately depicting a black hole as seen from a close by observer. Pretty cool.

I read that it was mostly about making the black hole less confusing and arcane to viewers to prevent them getting distracted from the movie. They toned down the red/blue shifting and relativistic beaming of the accretion disk quite a bit, also the "shape" would look warped since the black hole in the movie is rotating.

EDIT: Example of realistic warping due to spin: http://cdn.iopscience.com/images/0264-9381/32/6/065001/Full/cqg508751f14_online.jpg

Compare to movie: http://cdn.iopscience.com/images/0264-9381/32/6/065001/Full/cqg508751f16_online.jpg

Look at some of the maths in that paper though lol, pretty cool stuff (Appendix A2 is good).

I read that it was mostly about making the black hole less confusing and arcane to viewers to prevent them getting distracted from the movie. They toned down the red/blue shifting and relativistic beaming of the accretion disk quite a bit, also the "shape" would look warped since the black hole in the movie is rotating.

EDIT: Example of realistic warping due to spin:

Compare to movie: http://cdn.iopscience.com/images/0264-9381/32/6/065001/Full/cqg508751f16_online.jpg

Look at some of the maths in that paper though lol, pretty cool stuff (Appendix A2 is good).

Sex in Space Could Derail Mars Mission, Secret NASA Report Says | A mixed-gender crew would endanger the journey to Mars and back due the risk of male and female space travelers getting frisky during their one-and-a-half-year mission, an unreleased NASA study reportedly concluded.

Sex in Space Could Derail Mars Mission, Secret NASA Report Says | A mixed-gender crew would endan...

All I know is: Doggie style and Reverse Cowgirl are the same thing in space.

That sounds bollocks. Apart from the risk of pregnancies (easily avoidable!) how exactly can “getting frisky” affect missions? There can be jealousy, stress and infighting even with a all same gender heterosexual crew, and I’m sure the thousands of years of our experience with mixed genders on isolated vessels and villages have taught us how to deal with relationships and survive. Doesn’t the us navy already has mixed gender crews?

I mean, it would solve the problem of people getting laid in space, so that's good.

The Navy has had mixed gender crews for a while, but from everything I've heard, how well it goes varies wildly on a ship-to-ship basis. It's the kind of social circumstance that commanding officers have to know how to deal with, and if they don't (or just don't want to) things tend to get miserable.

It also requires a certain amount of rule-bending, because certain Navy-wide policies aren't conducive to mixed crews. So, for example, sexual relations among the crew are forbidden by Navy policy...but the ships that actually run smoothly tend to have a corpsman who's got a bunch of free condoms available. Things like that.

Source: secondhand through a bunch of Navy friends and family.

Elon Musk wants to use a rocket to go to any city on earth in under an hour

Elon Musk wants to use a rocket to go to any city on earth in under an hour

Methane yes... but burning it produces CO2 and H2O.

This is sort of nonsensical though - this comment is like someone in the 1940s looking at air safety and saying flight was doomed as a concept.

I really wonder why it is in every generation you have people who ignore lessons of the past?

planes already often crash

Not really that often. Isn't airplanes far safer than travelig by road? Maybe I'm mistaken. Unable to research atm.

Its actually a fine use of resources considering the mentality of disposable consumerism prevalent in the developed world. Have you ever been to a Spencer's Gifts store? That is a gallery of wasted resources.

BFR | Earth to Earth

BFR | Earth to Earth

What's up with the clown looking thing in the city lights at 1:14

Jesus... what were the 50s 60s and 70s then. It's no different. you're just more aware of it because of the internet.

I mean you had: Korea

Vietnam

Red scare

McCarthyism

Ballistic missiles

Segregation

Presidential assassinations

Berlin Wall

Polio epidemics

Proxy wars

North Korea same shit different Kim

The list goes on and on and on the world was way more fucked up the last time we left the planet.

It really makes me happy that even though we're living through rising tensions, weird global politics, the threat of nuclear war, climate change, etc, that something like this pops up and shows something optimistic and absolutely awe-inspiring about the future.

Let's hope we can make this a reality.

Whether this is "too expensive" for normal use or not, even if it's just for the elites, I'm 10000% for it. Normalization of reusable space technology funded by the rich wanting convenience is honestly the best thing you could even hope for. What more do you even want?

Try one of these subthreads