ancient greek word of the day: κλονοκάρδιος (klonokardios), heart-stirring, epith. of the thunderbolt
I would choose you in every life;
time after time, we meet again.
In between the planets, stars and other bits of rock and dust, space seems pretty much empty. But the super-spread out matter that is there follows a different set of rules than what we know here on Earth.
For the most part, what we think of as empty space is filled with plasma. Plasma is ionized gas, where electrons have split off from positive ions, creating a sea of charged particles. In most of space, this plasma is so thin and spread out that space is still about a thousand times emptier than the vacuums we can create on Earth. Even still, plasma is often the only thing out there in vast swaths of space — and its unique characteristics mean that it interacts with electric and magnetic fields in complicated ways that we are just beginning to understand.
Five years ago, we launched a quartet of satellites to study one of the most important yet most elusive behaviors of that material in space — a kind of magnetic explosion that had never before been adequately studied up close, called magnetic reconnection. Here are five of the ways the Magnetospheric Multiscale mission (MMS) has helped us study this intriguing magnetic phenomenon.
Magnetic reconnection is the explosive snapping and forging of magnetic fields, a process that can only happen in plasmas — and it’s at the heart of space weather storms that manifest around Earth.
When the Sun launches clouds of solar material — which is also made of plasma — toward Earth, the magnetic field embedded within the material collides with Earth’s huge global magnetic field. This sets off magnetic reconnection that injects energy into near-Earth space, triggering a host of effects — induced electric currents that can harm power grids, to changes in the upper atmosphere that can affect satellites, to rains of particles into the atmosphere that can cause the glow of the aurora.
Though scientists had theorized about magnetic reconnection for decades, we’d never had a chance to study it on the small scales at which it occurs. Determining how magnetic reconnection works was one of the key jobs MMS was tasked with — and the mission quickly delivered. Using instruments that measured 100 times faster than previous missions, the MMS observations quickly determined which of several 50-year-old theories about magnetic reconnection were correct. It also showed how the physics of electrons dominates the process — a subject of debate before the launch.
In the five years after launch, MMS made over a thousand trips around Earth, passing through countless magnetic reconnection events. It saw magnetic reconnection where scientists first expected it: at the nose of Earth’s magnetic field, and far behind Earth, away from the Sun. But it also found this process in some unexpected places — including a region thought to be too tumultuous for magnetic reconnection to happen.
As solar material speeds away from the Sun in a flow called the solar wind, it piles up as it encounters Earth’s magnetic field, creating a turbulent region called the magnetosheath. Scientists had only seen magnetic reconnection happening in relatively calm regions of space, and they weren’t sure if this process could even happen in such a chaotic place. But MMS’ precise measurements revealed that magnetic reconnection happens even in the magnetosheath.
MMS also spotted magnetic reconnection happening in giant magnetic tubes, leftover from earlier magnetic explosions, and in plasma vortices shaped like ocean waves — based on the mission’s observations, it seems magnetic reconnection is virtually ubiquitous in any place where opposing magnetic fields in a plasma meet.
Magnetic reconnection is one of the major ways that energy is transferred in plasma throughout the universe — and the MMS mission discovered that tiny electrons hold the key to this process.
Electrons in a strong magnetic field usually exhibit a simple behavior: They spin tight spirals along the magnetic field. In a weaker field region, where the direction of the magnetic field reverses, the electrons go freestyle — bouncing and wagging back and forth in a type of movement called Speiser motion.
Flying just 4.5 miles apart, the MMS spacecraft measured what happens in a magnetic field with intermediate strength: These electrons dance a hybrid, meandering motion — spiraling and bouncing about before being ejected from the region. This takes away some of the magnetic field’s energy.
Before we had direct measurements from the MMS mission, computer simulations were the best tool scientists had to study plasma’s unusual magnetic behavior in space. But MMS’ data has revealed that these processes are even more surprising than we thought — showing us new electron-scale physics that computer simulations are still trying to catch up with. Having such detailed data has spurred theoretical physicists to rethink their models and understand the specific mechanisms behind magnetic reconnection in unexpected ways.
Although MMS studies plasma near Earth, what we learn helps us understand plasma everywhere. In space, magnetic reconnection happens in explosions on the Sun, in supernovas, and near black holes.
These magnetic explosions also happen on Earth, but only under the most extreme circumstances: for example, in nuclear fusion experiments. MMS’ measurements of plasma’s behavior are helping scientists better understand and potentially control magnetic reconnection, which may lead to improved nuclear fusion techniques to generate energy more efficiently.
This quartet of spacecraft was originally designed for a two-year mission, and they still have plenty of fuel left — meaning we have the chance to keep uncovering new facets of plasma’s intriguing behavior for years to come. Keep up with the latest on the mission at nasa.gov/mms.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
Satellite imagery of the disruption of the polar vortex in the northern hemisphere winter 2012-2013. The data show a major stratospheric sudden warming (SSW) event, linked to the distortion and reversal of the normal westerly (moving west to east) flow of air.
The large vortex (bright) over the North Atlantic Ocean at the start of the clip breaks up into several smaller vortices. This is due to air from lower latitudes (dark) becoming entrained in the polar flow, forming an anti-cyclonic region (dark, rotating clockwise) over Japan and eastern Russia, which disrupts the flow across the region.
Although dramatic, such events are not rare, occurring every two years on average. They can cause winds to reverse near the surface too, leading to very cold spells, especially in North America and Europe.
The brightness indicates the potential vorticity of the air, a measure of its rotation within its flow, at an altitude of 35 kilometers. Brighter regions have more vorticity.
A major SSW occurs when the temperatures in the stratosphere around the pole increases by at least 25 Kelvin within a week, causing the wind to change direction.
The data were gathered by the GEOS-5 satellite every hour between 15th December 2012 and 28th January 2013.
© GMAO / GSFC / NASA / Science Source
On February 5, 1979, Voyager 1 made its closest approach to Jupiter since early 1974 and 1975 when Pioneers 10 and 11 made their voyages to Jupiter and beyond.
Credit: NASA
Planetary Satellites (1977)
Gökyüzüne sevgim hiç bitmeyecek belli ki ... 😌
do you still hear the stars?
A cosmic optical illusion by Hubble Space Telescope / ESA
two of my favorite things!! pins and space!! peak goblin performance is having at least one surface covered in pins.