{"id":5297,"date":"2022-12-21T22:00:00","date_gmt":"2022-12-21T22:00:00","guid":{"rendered":"https:\/\/modernsciences.org\/staging\/4414\/?p=5297"},"modified":"2022-12-09T06:27:36","modified_gmt":"2022-12-09T06:27:36","slug":"are-the-northern-lights-caused-by-particles-from-the-sun-not-exactly","status":"publish","type":"post","link":"https:\/\/modernsciences.org\/staging\/4414\/are-the-northern-lights-caused-by-particles-from-the-sun-not-exactly\/","title":{"rendered":"Are the northern lights caused by \u2018particles from the Sun\u2019? Not exactly"},"content":{"rendered":"\n
\n \n
\n \n PhotoVisions\/Shutterstock<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\nAlexander MacKinnon<\/a>, University of Glasgow<\/a><\/em><\/span>\n\n

What a spectacle a big aurora is, its shimmering curtains and colourful rays of light illuminating a dark sky. Many people refer to aurora as the northern lights (the aurora borealis), but there are southern lights<\/a> too (the aurora australis). Either way, if you\u2019re lucky enough to catch a glimpse of this phenomenon, it\u2019s something you won\u2019t soon forget.<\/p>\n\n

The aurora is often explained simply<\/a> as \u201cparticles from the Sun\u201d hitting our atmosphere. But that\u2019s not technically accurate except in a few limited cases. So what does happen<\/a> to create this natural marvel<\/a>?<\/p>\n\n

We see the aurora when energetic charged particles \u2013 electrons and sometimes ions \u2013 collide with atoms in the upper atmosphere. While the aurora often follows explosive events on the Sun, it\u2019s not quite true to say these energetic particles that cause the aurora come from the Sun.<\/p>\n\n\n\n

Earth\u2019s magnetism, the force that directs the compass needle, dominates the motions of electrically charged particles in space around Earth. The magnetic field<\/a> near the surface of Earth is normally steady, but its strength and direction fluctuate when there are displays of the aurora. These fluctuations are caused by what\u2019s called a magnetic substorm \u2013 a rapid disturbance in the magnetic field in near-Earth space.<\/p>\n\n

\n \"\"\n
\n Many people travel to high-latitude countries every year in the hope of seeing the northern lights.<\/span>\n Douglas Cooper<\/span>, Author provided<\/span><\/span>\n <\/figcaption>\n <\/figure>\n\n

To understand what happens to trigger a substorm, we first need to learn about plasma. Plasma is a gas in which a significant number of the atoms have been broken into ions and electrons. The gas of the uppermost regions of Earth\u2019s atmosphere is in the plasma state, as is the gas that makes up the Sun and other stars. A gas of plasma flows away continuously from the Sun: this is called the solar wind<\/a>.<\/p>\n\n

Plasma behaves differently from those gases we meet in everyday life. Wave a magnet around in your kitchen and nothing much happens. The air of the kitchen consists overwhelmingly of electrically neutral atoms, so it\u2019s quite undisturbed by the moving magnet. In a plasma, however, with its electrically charged particles, things are different. So if your house was filled with plasma, waving a magnet around would make the air move.<\/p>\n\n

When solar wind plasma arrives at the earth it interacts with the planet\u2019s magnetic field (as illustrated below \u2013 the magnetic field is represented by the lines that look a bit like a spider). Most of the time, plasma travels easily along the lines of the magnetic field, but not across them. This means that solar wind arriving at Earth is diverted around the planet and kept away from the Earth\u2019s atmosphere. In turn, the solar wind drags the field lines out into the elongated form seen on the night side, called the magnetotail.<\/p>\n\n

\n \"\"\n
\n A coronal mass ejection leaves the Sun, travelling towards the Earth\u2019s magnetic field (this image is not to scale).<\/span>\n SOHO (ESA & NASA)<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n

Sometimes moving plasma brings magnetic fields from different regions together, causing a local breakdown in the pattern of magnetic field lines. This phenomenon, called magnetic reconnection<\/a>, heralds a new magnetic configuration, and, importantly, unleashes a huge amount of energy. <\/p>\n\n

These events happen fairly often in the Sun\u2019s outer atmosphere, causing an explosive energy release and pushing clouds of magnetised gas, called coronal mass ejections, away from the Sun (as seen in the image above).<\/p>\n\n

If a coronal mass ejection arrives at Earth it can in turn trigger reconnection in the magnetotail, releasing energy that drives electrical currents in near-Earth space: the substorm. Strong electric fields<\/a> that develop in this process accelerate electrons to high energies. Some of these electrons may have come from the solar wind, allowed into near-Earth space by reconnection, but their acceleration in the substorm is essential to their role in the aurora.<\/p>\n\n

These particles are then funnelled by the magnetic field towards the atmosphere high above the polar regions. There they collide with the oxygen and nitrogen atoms, exciting them to glow<\/a> as the aurora.<\/p>\n\n\n\n

Now you know exactly what causes the northern lights, how do you optimise your chances of seeing it? Seek out dark skies far from cities and towns. The further north you can go the better but you don\u2019t need to be in the Arctic Circle. We see them from time to time in Scotland, and they\u2019ve even been spotted in the north of England<\/a> \u2013 although they\u2019re still better seen at higher latitudes.<\/p>\n\n

Websites such as AuroraWatch UK<\/a> can tell you when it\u2019s worth heading outside. And remember that while events on the Sun<\/a> can give us a few days warning, these are indicative, not foolproof. Perhaps part of the magic lies in the fact that you need a little bit of luck to see the aurora in all its glory.\"The<\/p>\n\n

Alexander MacKinnon<\/a>, Honorary Research Fellow, Physics and Astronomy, University of Glasgow<\/a><\/em><\/span><\/p>\n\n

This article is republished from The Conversation<\/a> under a Creative Commons license. Read the original article<\/a>.<\/p>\n\n","protected":false},"excerpt":{"rendered":"PhotoVisions\/Shutterstock Alexander MacKinnon, University of Glasgow What a spectacle a big aurora is, its shimmering curtains and colourful…\n","protected":false},"author":308,"featured_media":5277,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[13,17,14],"tags":[658,498,474],"class_list":{"0":"post-5297","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-earth","8":"category-math-and-the-sciences","9":"category-space","10":"tag-aurora","11":"tag-sun","12":"tag-the-conversation","13":"cs-entry","14":"cs-video-wrap"},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/5297","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/users\/308"}],"replies":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/comments?post=5297"}],"version-history":[{"count":1,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/5297\/revisions"}],"predecessor-version":[{"id":5298,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/5297\/revisions\/5298"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/media\/5277"}],"wp:attachment":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/media?parent=5297"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/categories?post=5297"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/tags?post=5297"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}