Another in a series of unusually strong solar storms hitting Earth produced stunning skies full of colors known as the Northern Lights or Aurora Borealis farther south than normal, including into parts of the United States and United Kingdom.
Columbia University Astronomy Prof. David Helfand explains the breathtaking phenomenon.
Columbia University Astronomy Prof. David Helfand explains the breathtaking phenomenon.
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00:00The main effect we get most of the time from the standard, sort of modest-sized solar flares
00:06is the northern lights, the aurora borealis, and the southern lights, the aurora australis,
00:11which are the colorful dancing lights you see if you're in far northern Alaska or Canada.
00:16Solar maximum means the Sun.
00:18It's most active, it's generating the most magnetic storms on its surface
00:22and the most ejections of high-energy particles towards the Earth.
00:26That follows an 11-year cycle.
00:28Well, we don't know why it's 11 years, so the Sun is, in other words, brightening
00:31in the sense that its total energy output, not the part we can see,
00:35but the total energy output is slightly higher by close to a tenth of a percent
00:40than it was five years ago.
00:42The result of this is that the Sun is rotating.
00:45The Sun rotates once around on its axis in 26 days,
00:48and beneath the surface it's rotating even faster.
00:51And the Sun, of course, is very hot, so all the particles are charged,
00:55and charged rotating particles generate magnetic fields.
00:58So these magnetic fields are generated below the surface of the Sun.
01:02They also drive a solar wind, which is a wind of particles,
01:07like the wind outside, that spreads out throughout the solar system.
01:11And they are, among other things, responsible for the northern lights,
01:14the aurora borealis, because when those charged particles hit the Earth's magnetic field,
01:18they spiral around the field and crash into the North Magnetic Pole,
01:22and that excites the air molecules to glow red and green and other colors.