![]() ![]() These charged particles are traveling at large fractions of the speed of light and have tremendous energy. (See Forbush decrease for short-term changes of GCR related to space strong solar events) But unlike the solar cycle, where bursts of activity can change the environment quickly, the GCR spectrum remains relatively constant in energy and composition, varying only slowly with time. Just as the solar cycle follows a roughly 11-year cycle, so does the GCR, with its maximum, however, coming near solar minimum. Near solar minimum, in the absence of many coronal mass ejections and their corresponding magnetic fields, GCR particles have easier access to Earth. Over the course of a solar cycle the solar wind modulates the fraction of the lower-energy GCR particles such that a majority cannot penetrate to Earth near solar maximum. The strong magnetic fields of the Sun modulate the GCR flux and spectrum at Earth. Because of this, these particles interact with and are influenced by magnetic fields. These nuclei are fully ionized, meaning all electrons have been stripped from these atoms. These highly energetic particles consist of essentially every element ranging from hydrogen, accounting for approximately 89% of the GCR spectrum, to uranium, which is found in trace amounts only. GCR originate outside the solar system and are likely formed by explosive events such as supernova. "That's useful for people who want to see it, and it's also useful for people who are concerned about the effects of space weather and currents in the upper atmosphere on communication and things like that.Galactic Cosmic Rays (GCR) are the slowly varying, highly energetic background source of energetic particles that constantly bombard Earth. "All these observations in aggregate help us to build better models of aurorae," she added. "And there's the less-exciting aspect of the citizen science observations," which are equally scientifically valuable. Scientists understand a lot about auroras, but not everything - "so there's the discovery aspect," MacDonald said. (Plus, crowdsourcing platforms like Aurorasaurus, which MacDonald founded, help aggregate the observations to help with prediction and analysis.) And the improvement in camera technology available to the public means such records are increasingly valuable to scientists' understanding of auroras in general. It's at the farthest reaches of dedicated scientific cameras, and it appears on wavelengths different from the usual auroras, which those cameras might not be prepared to document. (Image credit: Andy Witteman is the first visible indicator of that ion drift, which researchers had been investigating via satellite for around 40 years, she added.īecause the phenomenon was occurring outside the usual geographic range for frequent auroras, citizen scientists played a particularly valuable role in understanding STEVE, MacDonald said. The feature was visible for about an hour. STEVE ripples over Helena Lake Ranch, BC, Canada in the early evening. And scientifically, "it's an aspect related to that's further south than we ever had recognized … It tells us that the processes creating the aurora are penetrating all the way into the inner magnetosphere, and so that's a new aspect of it." "It's exciting because this might be a kind of aurora that more people can see than any other kind, because when it shows up, it shows up over more populated areas that are further to the south," Elizabeth MacDonald, a researcher at NASA's Goddard Space Flight Center in Maryland and lead author of the new work, told. (STEVE is short for "Strong Thermal Emission Velocity Enhancement.") According to the new work, the distinctive ribbon of purple light with green accents - which can occur at lower latitudes than normal auroras do - gives scientists a glimpse into the interactions of Earth's magnetic field and upper atmosphere. As of a new paper's release today (March 14), the phenomenon has been dubbed STEVE, a backronym that matches the name originally given by aurora watchers.
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