Cosmic rays are incredibly powerful invisible particles, and we can’t be sure where they come from. Not much in the way of a comforting thought, but it makes for a cosmic mystery that astronomers have been trying to solve for decades. And now they have come one step closer. Here’s what we do know. Cosmic rays are energetic atomic nuclei travelling at near the speed of light. They hit our atmosphere and rapidly interact with the molecules there to break into billions of smaller, less energetic particles that shower down on the life on Earth, without giving us much notice...
If a supernova were to go off somewhere in our galaxy, the minimum safe distance for Earthbound life would be about 50 light years. Any closer than that, and we would experience an intense blast of high energy radiation and an eventual shower of radioactive particles. It would be like nuclear bombs were set off all around the Earth, causing little destruction but a lot of radioactive fallout. Supernovae are incredibly powerful to be able to cause such damage at 50 light years, but even at larger distances, we can see evidence of their effects here on Earth. A team of...
Big stars tend to stick together. They all require incredibly dense regions in which to form, but once they do, they do a great job of blowing away and ionizing any other gas and dust in the vicinity. This is why nebulas in distant galaxies are great tracers of massive star formation. The bigger and hotter the star, the more UV light it produces, the more it ionized a gas cloud, the more we see gorgeous nebula. So it’s no surprise that when I look at the nebula below, I can guess that the central stars are huge, outweighing our...
After yesterday’s post about some data that has caused us to rethink a theory, I wanted to follow it up today with an even bigger bit of data that could substantially change an even bigger theory. Dark energy was discovered as a large-scale repulsive force in the universe that is responsible for the acceleration of its expansion. It was discovered by looking at type 1a supernovae in distant galaxies. since the supernovae all explode with the same mass limit, they appear to all have the same intrinsic luminosity. If we know how bright they actually are, we can compare them...
I always like to bring up the crazy ways in which two areas of science that seem completely disconnected can relate to each other, occasionally giving incredible insights. By looking at the ocean floor, a world human beings can’t reach without special pressurized equipment, we are learning about space, a world human beings can’t reach without special pressurized equipment. So how is the ocean teaching us about space? Physicists at the Australian National University have been studying seafloor dust that has been raining down on Earth as micrometeorites over the past 25 Million years. The dust is thought to originate...
