US universities have long been mistaken for who owns the world's largest drum. Unnamed claim titles include "Purdue Big Bass Drum" and "Big Bertha", which are interestingly named after the German World War I and became radioactive during the Manhattan Project.
However, unfortunately for the Americans, the Guinness Book of World Records says that a traditional Korean "CheonGo" holds a true title. It is over 5.5 meters wide, about 6 meters high (18 to 20 meters) and weighs more than seven tons.
But my latest scientific findings, published only in Nature Communications opponents. That is because the world's largest drum is actually a few tens of times bigger than our planet ̵
You may think this is nonsense. But the magnetic field (magnetosphere) that surrounds the Earth, which protects us through the diffusion of solar wind across the planet, is a huge and complex musical instrument.
We know 50 years or so that the weak magnetic types of sound waves can bounce around and reflect within this environment, which generates well-defined notes exactly in the same way make air and stringed instruments.
But these notes form at frequencies tens of thousands times lower than we can hear in our ears. And the instrument like the drum inside our magnetosphere has long been in us – until now.
Massive magnetic membrane
The main characteristic of a drum is its surface – referred to as a membrane (the drum is also known as membranophones). When you hit this surface, ripples can spread throughout it and return to fixed edges.
Original and reflected waves can interfere by strengthening or canceling each other. This leads to "standing wave patterns", where specific points appear to be standing still while others move back and forth.
Specific patterns and their associated frequencies are fully determined by the shape of the drum's surface. In fact, the question "Can someone hear the shape of a drum?" mathematicians have been understanding since 1960 until now.
The outer boundary of the Earth's magnetosphere, known as magnetopause, acts as a resilient membrane. It grows or diminishes depending on the different wind power levels, and these changes often trigger ripples or surface waves to spread across the boundaries.
As scientists are often focused on how these waves are descending to the sides of the magnetosphere, they should also travel to the magnetic poles.
Physicists are often complicated by problems and simplified them so much to gain insight. This approach helped the theorists 45 years ago to first demonstrate that these surface waves may get reflected back, making the magnetosphere vibrate like a drum.
But it is unclear if the removal of some of the simplification in theory may stop the drum from being feasible.
It is also very difficult to find interesting observational evidence for this theory from satellite data. In space physics, unlike astronomers say, we often deal with the incomparable sight.
We can not get a picture of what's happening anywhere, we need to send satellites and measure it. But that means we only know what's happening at locations where there are satellites.
The convention is often the case when the satellites are in the right place at the right time to see what you are looking for.
In the past few years, my colleagues and I have been more than generating this magnetic drum theory to give us testable signatures to search our data.
We were able to have some strict standards that we thought could provide evidence for these oscillations. This really means that we need at least four satellites all in a row near the magnetopause.
Fortunately, NASA's THEMIS mission did not give us four but five satellites to play. All we have to do is to get the right driving experience, which is equivalent to the drum stick that reaches the drum, and measure how the surface moves in response and what it sounds like.
The event The question is a jet of high-speed (plasma) particles that strangle the magnetopause. Once we have had, everything has fallen in place almost perfectly. We even created what the drum sound really is (see video above).
This research goes to show how much science is true. Something that looks pretty honest took us 45 years to show.
And this trip is far from over, there are a lot more activities to do to find out how often drum-like vibrations occur (both here on Earth and potentially on other planets, too) and what their consequences are in our space environment.
This will ultimately help us solve what kind of cadence the magnetosphere is releasing over time. Like a former DJ, I can not wait – I love a good beat.
Martin Archer, Space Plasma Physicist, Queen Mary University of London.
This article was republished from The Conversation under the Creative Commons license. Read the original article.