Five spacecraft have made a remarkable set of observations, leading to a breakthrough in understanding the origin of a peculiar and puzzling type of aurora. Seen as bright spots in Earths atmosphere and called "dayside proton auroral spots," they are now known to occur when fractures appear in the Earths magnetic field, allowing particles emitted from the Sun to pass through and collide with molecules in our atmosphere.
On March 18, 2002, a jet of energetic solar protons collided with the Earths atmosphere and created a bright "spot" seen by NASAs IMAGE spacecraft, just as the European Space Agencys (ESA) four Cluster spacecraft passed overhead and straight through the proton jet. This is the first time that a precise and direct connection between the proton jet and bright spot has been made, and it results from the simultaneous observations by Cluster and IMAGE. The results of the study are published May 21 in Geophysical Research Letters, a journal of the American Geophysical Union, in a paper by Tai Phan of the University of California in Berkeley and 24 international colleagues.
Earths magnetic field acts as a shield, protecting the planet from the constant stream of tiny particles ejected by the Sun, known as the solar wind. The solar wind itself is a stream of hydrogen atoms, separated into their constituent protons and electrons. When electrons find routes into our atmosphere, they collide with and "excite" the atoms in the air. When these excited atoms release their energy, it is emitted as light, creating the glowing "curtains" we see as the aurora borealis in the far north and aurora australis in the far south. Dayside proton auroral spots are caused by protons "stealing" electrons from the atoms in our atmosphere.
An extensive analysis of the Cluster results has now shown that the region was experiencing a turbulent event known as "magnetic reconnection." Such a phenomenon takes place when the Earths usually impenetrable magnetic field fractures and has to find a new stable configuration. Until the field mends itself, solar protons leak through the gap and jet into Earths atmosphere, creating the dayside proton aurora.
Philippe Escoubet, ESA’s Cluster Project Scientist, comments, "Thanks to Clusters observations, scientists can directly and firmly link for the first time a dayside proton auroral spot and a magnetic reconnection event."
Tai Phan, leader of the investigation, now looks forward to a new way of studying the Earths protective shield. He says, "This result has opened up a new area of research. We can now watch dayside proton aurorae and use those observations to know where and how the cracks in the magnetic field are formed and how long the cracks remain open. That makes it a powerful tool to study the entry of the solar wind into the Earths magnetosphere."
Proton auroras were globally imaged for the first time by NASAs IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) spacecraft, which revealed the presence of dayside proton auroral spots. ESAs Cluster is a collection of four spacecraft, launched on two Russian rockets during the summer of 2000. They fly in formation around the Earth, relaying the most detailed information ever about how the solar wind affects the planet.
The principal investigators for the instruments in the current study were Henri Reme of CESR/Toulouse, France (Cluster Proton Detectors), Andre Balogh of Imperial College, London, United Kingdom (Cluster Magnetic Field Instrument), and Stephen Mende of University of California, Berkeley (IMAGE/FUV).
The current study was funded by NASA and other organizations.
Harvey Leifert | AGU
New method gives microscope a boost in resolution
10.12.2018 | Rudolf-Virchow-Zentrum für Experimentelle Biomedizin der Universität Würzburg
A new 'spin' on kagome lattices
10.12.2018 | Boston College
What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.
Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...
Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.
Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...
New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals
Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.
Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.
Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...
Scientists from the Theory Department of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science (CFEL) in Hamburg have shown through theoretical calculations and computer simulations that the force between electrons and lattice distortions in an atomically thin two-dimensional superconductor can be controlled with virtual photons. This could aid the development of new superconductors for energy-saving devices and many other technical applications.
The vacuum is not empty. It may sound like magic to laypeople but it has occupied physicists since the birth of quantum mechanics.
10.12.2018 | Event News
06.12.2018 | Event News
03.12.2018 | Event News
10.12.2018 | Life Sciences
10.12.2018 | Physics and Astronomy
10.12.2018 | Life Sciences