Remember last week when I was talking about the evidence for some ancient-but-astronomically-recent supernovae? It turns out there is other evidence! Evidence that has helped scientists narrow down the potential source locations. Data from the Cosmic Ray Isotope Spectrometer (CRIS), an instrument aboard NASA’s Advanced Composition Explorer (ACE) spacecraft, has helped us figure out where the recent supernovae might have come from. CRIS measures what we call cosmic rays, atomic nuclei that have been accelerated across the galaxy at close to the speed of light. CRIS has been around for a while, and through 17 years of cosmic ray observations,...
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...
With the recent discovery of gravitational waves, we now have a target for probing the very early universe, close to the big bang. This is because gravitational waves can travel across the universe unimpeded, meaning those created after the big bang are still bouncing around today. It’s like the big bang was the ringing of a giant bell, and the ringing can still be heard. But all of our Easter eggs are not in one basket. There is another way to probe the very early universe, one we haven’t found yet, because it involves particles that are very tiny and...
When we see the Earth’s only Moon up in the sky, we often think about how small it is. It’s only about 1/4 the diameter of the Earth, and at a distance of 384,000 Km, it looks small in the sky. But often size is entirely a matter of perspective. What we compare something to, that’s what determines it’s size. When the Moon is high in the sky we easily compare it to the size of the window we are looking through, or to a nearby tree, or our outstretched hand. All of this can make the Moon seem pretty tiny....
For the first time in 30 years, the United States has the capability to produce fuel for deep space missions. Plutonium-238 is an isotope that produces thermal energy through radioactive decay. This energy can be converted into electricity and used to power spacecraft systems for decades of flight. Systems using this isotope include the Viking landers, the Voyager spacecraft, and more recent missions like the Mars Science Laboratory (Curiosity) and New Horizons. The Oak Ridge National Laboratory in Tennessee, run by the US Department of Energy, has produced 50 grams of the isotope, amounting to the size of a golf...
The Sun. A bright fiery light in the sky to some, worshipped as a god by others, seen as a massive ball of hydrogen plasma 150 million kilometres away by scientists. Once in a while, the Sun goes ahead and releases massive amounts of charged plasma particles toward the Earth. The particles should eradicate humanity with horrible burns and render our planet lifeless, but luckily… they don’t. Why? The Earth’s magnetic field protects us, funnelling the particles to the poles where they ionize gases in the atmosphere and become harmless. The bonus for humanity, aside from not dying, is that we...
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...
