Cosmic rays are a very interesting form of radiation. They are a stream of extremely high energy particles, travelling at almost the speed of light, originating from very high energy events in our universe. It is believed that supernovae are a major source of cosmic rays. However, a lot about these particles is still a mystery.
An incredible three million of these particles, each with energy as much as a fast baseball, go through you every day. And yet, we are never aware of something like that happening. The earth magnetic field protects us from the full brunt of these rays, still a significant number of them are able to pass.
Another interesting thing about them is that when they strike the earth’s atmosphere, they form particles called pions which decay into muons. Muons have a very short lifespan. They don’t exist for more than a few micro seconds. Which means they shouldn’t be able to travel more than a few hundred meters.
Yet millions of them, travel great distances, and go through each of our bodies everyday. That is because, since they travel at almost the speed of light, relativistic effects come into play. Time is slowed down for them. So, from our frame of reference they are able to exist for a far longer time and reach us.
They are far too small to be seen or noticed. But did you know, the foot prints of these particles raining through your body can actually be seen? In fact, they can be seen using a simple $30 spark chamber constructed at home. See the video below.
Manaus is the capital city of the state of Amazonas in northern Brazil. The city is situated at about a 10 kilometre distance from the confluence of the Negro and Solimões rivers – two big tributaries of the Amazon river. While these are two names which you must haven’t probably heard of, the place where they meet is a very interesting place.
The first river, Rio Solimões is a water body full of sediments that wash down with it from the Andes mountains. Thanks to the sand, mud and silt that comes washing with it, the river looks muddy, the colour is light brown, nearly. The locals call it the white river.
On the other hand, we have the Negro river (or Rio Negro). It has significantly darker coloured water due to the presence of humic acid from incomplete breakdown of phenol-containing vegetation from sandy clearings. Although the locals call it the black river, it isn’t exactly black. The colour is very similar to a black tea concoction. However, the colour of Rio Negro is very different from Rio Solimões. Here’s how they look from up above.
At the place where they meet, the rivers don’t mix. They leave a fairly clear boundary and flow side by side without mixing for about six kilometres. That happens because of the big difference in their flow speed, density and temperature.
While the river Solimões is a fast flowing (6 km per hour), high density (due to the sediments) and cooler river, the other river flows much slower (one third of the speed of Solimões river), is warmer and is less dense (because it is much cleaner). These differences cause the rivers to meet and not mix. Much later, about 6 kilometres later, these differences attain equilibrium and the rivers merge into the main Amazon river.
Perfect circles of ice have been seen spinning on top of water bodies for quite some time. They aren’t perfectly round most times. Recently, in the month of November last year, a huge 17 meter spinning ice disk was spotted on the river Sheyenne in North Dakota.
Several such ice disks have also been seen in the past in Canada, England and Sweden. Similar ice swirls were also seen in the Charles river, Boston. Some times they are huge, other times you see a number of tiny clusters of such ice swirls.
As always, even ice circles aren’t the work of aliens or government spies. It is completely a natural phenomena which occurs when slowly moving water moves past an obstacle creating a slow moving eddy. In due time, and due to very low temperatures, ice circles form small and keep growing as rings of frozen water on the surface of the water body keeps adding to their diameters. Here’s a video of one such big, and almost perfect, ice circle which was spotted in Rattray Marsh, Canada.