Ahr river
I was linked here from the Random Questions thread, but I was wondering if anyone had good sources on blackholes to get a basic understanding on how they work?
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You could always start with our own page on the subject
There's also Crash Course Astronomy's video on the subject.
Just as starting points.
Ahr river
Thank ye kindly :)
Read my stories!
Professional Forum Ninja
Talk about unlucky.
Makes a good epitaph though
Carve his headstone out of the meteorite.
Gravitational waves from the collision of two black holes have been detected for the first time
They are saying that this discovery is equivalent to the invention of the telescope in importance to astronomy.
Jupiterian Local
Yeah, it's pretty ridiculous. It's basically a new kind of telescope — one that detects gravity waves rather than electromagnetic radiation. With just two detectors (one in Louisiana, one in Washington state), they were able to determine that the event they detected was the result of two black holes, 29 and 36 solar masses, colliding with each other 1.3 billion years ago (and thus 1.3 billion light years away, as gravity waves propagate at the speed of light) in the sky over the southern hemisphere. With more detectors, they'll be able to triangulate that more accurately.
Just for reference at how ridiculous this is, the gravity wave had the energy equivalent to three solar masses converted directly into energy and this single event briefly (as in, for less than a second) outshined the entire rest of the visible universe.
edited 11th Feb '16 9:09:45 AM by NativeJovian
Really from Jupiter, but not an alien.
I take it you are using 'ridiculous' in the same way as people who say somethng is 'sick' when they mean it is very cool.
For every complex problem there is an answer that is clear, simple, and wrong. — H.L. Mencken
The Mod with the Migraine
Look out below, Russia will be launching ICBMs at asteroids soon.
The United States is also working on ways to prevent asteroids from hitting Earth, but is taking a very different approach. Instead of blowing up the space rocks, NASA plans to shove them away from the planet. It is the latest frontier in efforts by both countries to tackle a threat to the planet that dates at least from the extinction of the dinosaurs.
The Russian missiles would be used to target smaller asteroids of 20 meters to 50 meters in diameter. These smaller asteroids can cause significant damage and can sometimes be detected only by observatories a few hours in advance of their reaching Earth. Sometimes, they aren't detected at all. In 2013, a 20-meter-wide meteor exploded in the sky over Chelyabinsk, Russia, with the estimated force of 300,000 tons of TNT or more, shattering glass in buildings and leaving more than 1,000 people injured. None of Earth's space agencies saw it coming.
"Unfortunately, we only know about roughly 1% of those asteroids that get down to the 30-meter size, so there's a tremendous amount out there that we have yet to discover," noted Jason Kessler, the director of NASA's effort to find all asteroid threats to human populations. Larger asteroids can cause much more damage but can be detected early by space observatories using advanced telescopes and infrared technology.
Kessler said that NASA calculates it has "discovered about 95% of the one kilometer or larger asteroids," roughly the size of the one thought to have wiped out the dinosaurs upon impact. Unlike rockets that deliver satellites to orbit or ferry people and supplies to the space station, intercontinental ballistic missiles, or ICB Ms, are designed to be used during a war and can launch at a moment's notice.
The prospect of Russia modifying nuclear missiles for outer space is likely to cause alarm within the U.S. military. The office of the Director of National Intelligence has already expressed concern about Russian military activities in space. Its 2016 threat assessment says that Russia continues "to pursue weapons systems capable of destroying satellites on orbit." The assessment notes that "the Russian Duma officially recommended in 2013 that Russia resume research and development of an airborne antisatellite missile to 'be able to intercept absolutely everything that flies from space.'" Russia has large numbers of nuclear-armed ICB Ms in its strategic arsenal that could potentially be converted. It is unclear if the Russian plan would use a conventional explosive in the repurposed missile, but its targeting system is likely to require significant modifications.
Saitgarayev acknowledged in the TASS interview that the modifications would take time and cost millions of dollars but said they are aiming to test the new missile against the larger 355-yard asteroid Apophis that is due to pass close to Earth in 2036.
Astrophysics professor Henry Melosh of Purdue University cautioned against the nuclear option, calling the effort "misguided and potentially dangerous." Melosh worked on NASA's Deep Impact mission. The spacecraft dropped an impactor onto a comet in 2005. Melosh downplayed the threat posed by smaller asteroids and told CNN, "There are other, safer ways to deflect asteroids with long lead times."
He pointed to kinetic deflection, which would fire a rocket into the asteroid to knock it off course, or gravity tractors, which uses a spaceships gravity field to nudge the asteroid off its trajectory. "For now, the best thing we can do is to identify potentially hazardous asteroids in space and project their time and location of impact," he said. According to Melosh, there are also ongoing efforts at the two U.S. nuclear weapons research centers, Los Alamos National Laboratory and Lawrence Livermore National Laboratory, to investigate the possibility of using nuclear weapons against larger asteroids with long warning times.
Paul Miller, associate division leader of the Design Physics Division at Lawrence Livermore, told CNN that the institution was "supporting NASA by modeling deflection techniques, including kinetic impactors or nuclear explosions." Miller added, "We know of no interest in the U.S. in repurposing ICB Ms" and questioned their utility in preventing asteroid impacts.
Deflection intercepts need to occur months, years or decades in advance, and the associated intercept locations are typically very far from Earth, he said. And he assessed that other developments would be more effective. As asteroid detection surveys improve, he said, "they should provide decades of warning. In that case, a ready-to-launch capability is unnecessary."
NASA wouldn't address the possibility of using nuclear weapons to destroy asteroids and would not comment on the viability of the Russian undertaking, but is emphasizing its nonnuclear approach. One way NASA plans to protect Earth from asteroids is to push the asteroids away from the planet. The space agency is developing an Asteroid Redirect Mission — the "first-ever robotic mission to visit a large near-Earth asteroid" and "redirect it into a stable orbit around the moon." This mission is primarily intended to study asteroids and is projected to be ready for deployment in the 2020s.
Ben Reed, who heads up the team developing the Redirect Mission, told CNN in June that the robotic lander could use its thrusters to nudge an asteroid off a collision course with Earth. Or alternatively, he said, the lander could use its own gravitational pull to make slight changes to an asteroid's trajectory if it were deemed a danger. "We have the technologies to mitigate any potential threats," Reed said.
NASA also announced in January that it has formalized its program for detecting and tracking asteroids that could threaten Earth. The new program is called the Planetary Defense Coordination Office. NASA said the office will take a leading role in coordinating a response to any potential asteroid impacts. In a press release announcing the office, the agency said its "long-term planetary defense goals include developing technology and techniques for deflecting or redirecting objects that are determined to be on an impact course with Earth."
When they first decided to look at Pluto, I thought all they'd fine is a boring icy rock. But I was wrong. Dead wrong. I guess it's trying to get promoted, so its looking its best.
The Wanderer
ATLASGAL survey of Milky Way completed: "A spectacular image of the Milky Way has been released to mark the completion of the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). The APEX telescope has mapped the full area of the Galactic Plane visible from the southern hemisphere for the first time at submillimeter wavelengths and in finer detail than space-based surveys. The APEX telescope allows the study of the cold universe, a few tens of degrees above absolute zero."
Cogito ergo cogito
Why is it that it somehow fits the trope of "those brutish russians" so perfectly that they will just blow the asteroids up, instead of nudging them away. 
A nice butterfly
IN SOVIET RUSSIA, ARMAGEDDON HAPPEN IN ASTEROID
It has always been the prerogative of children and half-wits to point out that the emperor has no clothes
What about the Outer Space Treaty?
A procrastination in of itself
It bans the stationing of weapons in outer space, if you fire them from on earth at a target in space there would be no violation.
It looks like space advocacy is making a political comeback, getting funds, and people are avoiding falling into a rut. Loud naysayers hopefully won't be able to shut down these efforts, due the existence of prominent private space companies now.
A procrastination in of itself
I'm not sure, once the ISS ends we may end up in a rut, hopefully though the lack of the ISS will push us to do new things.
Private companies may well fill the void a bit, but I doubt they will innovate and push boundaries the way we need.
Hopefully the end of the ISS will also see more widespread activity, the ESA (and the Japanese) has been playing second fiddle to NASA for a while and I think they need to push out on their own. Hopefully the Indians will also push the envelope out.
I've actually been wondering something, how different are the requirements to get into orbit and to move from one orbit to another? If we get single stage to orbit spacecraft, how hard would it be to go beyond orbit? What's stopping a space plane flying all the way to the moon?
“And the Bunny nails it!” ~ Gabrael “If the UN can get through a day without everyone strangling everyone else so can we.” ~ Cyran
Jupiterian Local
The mechanics of space travel are all about what's called delta-v ("delta" as in the mathematical denotation for "change in" and "v" for "velocity"). Essentially, for the purposes of orbital mechanics, the important question isn't how high up you are, but how fast you're going. The specifics get into some pretty intense math, but the short version is that your delta-v budget (how much delta-v your spacecraft is capable of) determines what missions you can perform.
From Earth surface to low Earth orbit (LEO, where the ISS is and all the space shuttle missions went to) requires a delta-v of around 7.8 km/s (though the actual amount of delta-v your rocket will need is raised by air resistance and lowered by the "free ride" it gets from the rotation of the planet, and ends up being about 9-10 km/s). From LEO to LLO (low lunar orbit) is just over 4 km/s, and from LLO to the surface of the Moon is 1.87 km/s.
Total those values up (10 + 4 + 1.87) and you get 15.87 km/s. Of course, that's for a one-way trip. To come back again, you need to get back to lunar orbit and then to LEO (from LEO to Earth's surface you can use aerobraking, which is "free" as far as delta-v is concerned, though it does come with a mass penalty to your ship in the form of a heat shield. This is almost always less mass than additional propellant would be, though.) So that gives us 15.87 + 1.87 + 4 = 21.74. More than double what's necessary just to get into LEO in the first place.
For reference, getting to Mars (one way) requires about 16.6 km/s to reach low Mars orbit, at which point you can aerobrake to the surface for free. You might notice that this isn't all that much than it takes to get to the Moon, and you'd be right. The hard part of getting to Mars isn't the rocketry itself, it's either designing a payload that can land itself automatically (the light-speed delay between Earth and Mars is too long to remote-control anything) or else keeping a bunch of humans alive for the ~9 months it takes to get from Earth to Mars (not to mention back).
Really from Jupiter, but not an alien.
𐀀𐀩𐀯𐀂𐀰𐀅𐀡𐀄
The Wanderer
Deadly stars: Our sun could also be superflare star: "Every now and then large sun storms strike the Earth where they cause aurora and in rare cases power cuts. These events are, however, nothing compared to the apocalyptic destruction we would experience if the Earth is struck by a superflare. An international research team has now shown that this is a scenario we may have to consider a real possibility."
Earth's moon wandered off axis billions of years ago: "A new study reports Earth's moon wandered off its original axis roughly 3 billion years ago. Ancient lunar ice indicates the moon's axis slowly shifted by 125 miles, or 6 degrees, over 1 billion years. Earth's moon now a member of solar system's exclusive 'true polar wander' club, which includes just a handful of other planetary bodies."
Pentagon opens investigation into contracts with ULA
edited 26th Mar '16 7:33:01 AM by optimusjamie
Direct all enquiries to Jamie B Good
My name's Ben.
If I understand correctly, current astrophysics predicts that dark energy will get stronger and stronger until gravity effectively stops being a thing.
Would that imply a delta in the inverse square law or should I describe it in some other way?
Great men are almost never good men, they say. One wonders what philosopher of the good would value the impotence of his disciples.
From what I can gather reading the articles its more a case of firming up the specifics, including things like impact angle and velocity, including the fact that it was probably closer to head on that the previous scenario's glancing impact.