74363389
submission
StartsWithABang writes:
In our own Solar System, there are the four gas giant worlds, the four inner rocky worlds, and then a bunch of icy and rocky bodies smaller than those. But in other solar systems, there’s a whole class of worlds in between the size of Earth and Neptune, called either super-Earths or mini-Neptunes. This class not only exists, but it’s the most common type of planet in the Universe, to the best of our knowledge. Here's why we think we don't have one (now), owing to the unique, migratory history of our own planets.
74346067
submission
StartsWithABang writes:
A scientific theory needs to meet three criteria: it needs to explain all the successes of the previous leading theory, it needs to explain any failures or shortcomings that its predecessor couldn't, and it needs to make new, testable predictions that can either be falsified or verified. If the Multiverse doesn't meet that third criterion, can it be considered science? A fascinating exploration leads us to conclude that no, perhaps it isn't science after all.
74321109
submission
StartsWithABang writes:
Naming the planets in order and recognizing what they look like from their famous images might seem like an easy task. But an unfamiliar view, a focus on a single feature or a comparison with two similar images from other worlds can prove an incredibly difficult task. Take these two planet identification quizzes and see for yourself; the Solar System may be incredibly diverse, but the eight planets are often awfully hard to tell apart!
74289179
submission
StartsWithABang writes:
On Monday, xkcd asked 36 solar system questions, providing brief answers (and non-answers) to a few of them. But not only do most of them have actual, legitimate scientific answers, most of the ones that don't have had a lot of progress made on them. To the best of science's knowledge, here are the best answers to all 36 of them.
74264417
submission
StartsWithABang writes:
Back in the 1820s, Heinrich Olbers put forth his famous paradox: that if the night sky was filled uniformly and infinitely with stars, eventually the human eye should encounter one in any and all directions. Yet the darkness of the night sky clearly showed this was not the case! In modern times, the Big Bang provides a solution to this by showing that there is a finite age to the Universe, and hence a time before which there were no stars. There is a leftover glow, but it’s redshifted into the microwave region, visible as the CMB. And perhaps surprisingly, Poe — writing in 1848 — proposed a very Big Bang-like solution to Olbers’ paradox!
74132931
submission
StartsWithABang writes:
If there’s one thing you can be certain of when it comes to the fundamental, scientific truths of our Universe, it’s this: someday, in the not too distant future, those truths will be superseded by more fundamental ones. And even those, quite likely, won’t be the final truths, but just one step further along the line towards our understanding of reality. Does this mean that we’ve necessarily got it all wrong, and that we might just as well ignore the successes of our best theories so far? Does it mean that all we know about the Universe could easily be upended and replaced, leading to vastly different conclusions to questions like where everything came from? These are exceedingly unlikely, for a myriad of reasons. Instead, this is what the next major scientific revolution will probably look like.
74132477
submission
StartsWithABang writes:
There are few things as closely associated with American independence as our willingness and eagerness to celebrate with fiery explosions. I refer, of course, to the unique spectacle of fireworks, first developed nearly a millennium ago halfway across the world. But these displays don’t happen by themselves; there’s an intricate art and science required to deliver the shows we all expect. So what’s the science behind fireworks? Here's the physics (and a little chemistry) behind their height, size, shape, color and sound, just in time for July 4th!
74108169
submission
StartsWithABang writes:
From helium up through uranium continuously, every element in the periodic table can be found, created by natural processes, somewhere in the Universe. (With many trans-uranic nuclides found as well.) Yet out of all of those, only three of them aren't created in stars: lithium, beryllium and boron. Boron in particular is necessary for life as we know it, as without it, there would be no such things as plants. Here's the cosmic story of the only three heavy elements to exist that aren't made in stars.
74106027
submission
StartsWithABang writes:
When we talk about humans existing on worlds other than Earth, the first choice of a planet to do so on is usually Mars, a world that may have been extremely Earth-like for the first billion years of our Solar System or so. Perhaps, with enough ingenuity and resources, we could terraform it to be more like Earth is today. But the most Earth-like conditions in the Solar System don't occur on the surface of Mars, but rather in the high altitudes of Venus' atmosphere, some 50-65 km up. Despite its harsh conditions, this may be the best location for the first human colonies, for a myriad of good, scientific reasons.
74081867
submission
StartsWithABang writes:
There’s something puzzling about black holes, if you stop to consider it. On the one hand, they’re objects so massive and dense — compacted into such a small region of space — that nothing can escape from it, not even light. That’s the definition of a black hole, and why “black” is in the name. But gravity also moves at the speed of light, and yet the gravitational influence of a black hole has absolutely no problem extending not only beyond the event horizon, but infinite distances out into the abyss of space. The resolution involves some intricate physics about the event horizon itself, but the net result is that gravity works just the same outside the event horizon as if there were no horizon at all.
74057803
submission
StartsWithABang writes:
Of all the worlds in our Solar System, Venus is perhaps the most like Earth. It’s the closest to us in size, in mass, in orbit, and in elemental content. The biggest difference, of course, is Venus’ atmosphere. Over 90 times as thick as Earth’s and composed of carbon dioxide and thick sulfuric acid clouds, the surface of Venus is at a constant 465C (870 F), making it the hottest planet in the Solar System. Yet we’ve both landed on the surface and imaged the entire world through its clouds, finding out exactly what the Venusian surface looks like. Come learn what you're looking at in advance of Tuesday evening's big conjunction!
73984705
submission
StartsWithABang writes:
When we look out at the galaxies in the Universe, watching how they rotate, we find that the starlight we see is woefully insufficient to explain why the galaxies move as they do. In fact, even if we add in the gas, dust, and all the known matter, it doesn’t add up. Normally, we talk about dark matter as the only viable solution, but it turns out that MOND, or MOdified Newtonian Dynamics, is actually superior at explaining galactic rotation to dark matter. Could it be the solution to the “missing mass” (or “missing light”) problem? A look at the full suite of cosmological evidence reveals the answer, and sets out definitive challenges for MOND to overcome.
73966799
submission
StartsWithABang writes:
Static electricity is often the first exposure to physics beyond gravity that we encounter in our lives. Simply rub a balloon against a piece of fabric, and you can stick it to almost anything (or anyone) you like, possibly to their chagrin. But the way you probably learned that it happens — rub two materials together, one picks up a positive charge and the other gets a negative charge — is not only a little naive, it turns out not to account for the static electricity effects we observe at all. And oddly enough, we only determined this back in 2011 for the first time, shocking for one of the oldest known physical phenomena!
73932747
submission
StartsWithABang writes:
When we look out into the Universe, farther back to greater distances, we’re also looking back in time, farther and farther into the past. If we could look back far enough, close enough to the Big Bang, we’d be able to see the very first stars ever formed in the Universe: stars formed from the Big Bang’s leftover material itself. We’d never been able to find these before, but by looking at a starburst galaxy at extremely high redshifts, and measuring its signature spectroscopically, we were able to find strong evidence of hydrogen and helium, but none of carbon, oxygen, or any of the other “first-processed” elements we’d expect had we formed stars before. Here's why we think we've finally found the first true sample of Population III stars, with an actual exclusive interview with the lead scientist who made the discovery.
73877231
submission
StartsWithABang writes:
The Sun consists of some 10^57 particles, nearly 10% of which are in the core, which ranges from 4-15 million K, hot enough for nuclear fusion to occur. A whopping 4 × 10^38 protons fuse into helium-4 every second, and due to the temperatures and densities inside, the raw protons undergo billions of collisions during that time. Yet none of those collisions have a sufficient energy to overcome the Coulomb barrier; it's only through the power of quantum mechanics that any fusion occurs. Without this inherent indeterminism, the Sun and practically every star in the night sky would be eternally dark.
