general constrained to a local region, causing what’s known as a solar flare.
A FLARE FOR DANGER
By coincidence, a solar flare was first observed in 1859—the same year Heinrich Schwabe published his discovery of the sunspot cycle.
On September 1, 1859, astronomers Richard Carrington and Richard Hodgson were independently observing the Sun. Before their eyes, a small part of its normally calm disk suddenly exploded in intensity, becoming far brighter. This burst of emission lasted for five minutes, and even to this day may have been the most luminous flare ever observed. Within a few hours of the observations of the flare, magnetometers (instruments that measure the strength and direction of a magnetic field) on Earth went crazy, registering huge fluctuations in the Earth’s magnetic field.
The Solar and Heliospheric Observatory detected this massive flare from the Sun on November 4, 2003. It was one of three huge flares that surprised scientists that day; no such string of events had ever been witnessed before. They marked one of the most active weeks for the Sun ever recorded.
SOHO (ESA & NASA)
They didn’t know it then, but at that moment the study of space weather was born.
They also couldn’t have known that the flare was caused when tangled magnetic field lines on the surface of the Sun suddenly realigned themselves. The energy stored in them was released like a bomb—the equivalent of 15 billion one-megaton nuclear weapons, or 10 percent of the total energy output of the Sun every second concentrated into one spot—hurling high-energy photons (particles of light) and subatomic particles both upward into space and downward onto the surface of the Sun. A typical flare from the Sun ejects billions of tons of subatomic particles outward at speeds that reach five million miles per hour—and in 2005, one extraordinary flare launched a blast of protons that reached the Earth in just fifteen minutes, indicating they were traveling at one-third the speed of light. These subatomic particles blast outward, generally straight out from the center of the flare. Because of this, the particles launched upward and outward from the flare are generally not a problem to us on Earth: they are focused enough that they usually miss us, causing no grief.
But along with the particles shot into space, a huge pulse of particles is shot down, onto the surface of the Sun. This heats the gas there tremendously, and creates an incredibly strong pulse of light. Now, that may not sound like a big problem; after all, how bad can light be?
Bad. But it depends on the kind of light.
What we call “visible light” is a narrow slice of a much wider range of electromagnetic radiation. Infrared light, for example, has less energy than visible light, and radio waves have less energy still. Ultraviolet (UV) light has more energy than the light we can see. Still higher-energy light is X-rays, and on up to gamma rays. UV, X-, and gamma rays are dangerous in large quantities. Each photon carries so much energy that it can radically alter any atom it hits, stripping off the atom’s electron, ionizing it.
Flares give off a lot of this kind of light. And unlike the particles of matter emitted in a solar flare, this light spreads out. A flare on the edge of the Sun’s disk will almost certainly miss us with its particles, but any flare anywhere on the visible surface of the Sun is a potential danger because of the high-energy light it emits.
Picture a solar flare on the Sun: the tangled magnetic field lines over a sunspot suddenly snap, rearranging themselves, and releasing their energy. They heat the local gas up to millions of degrees, and a blast of X-rays surges outward.
Traveling at the speed of light, the high-energy radiation takes a little over eight minutes to travel the 90 million or so miles to the Earth. When it does, it slams into everything in its way: satellites, astronauts, and even the Earth’s atmosphere.
On the
A FLARE FOR DANGER
By coincidence, a solar flare was first observed in 1859—the same year Heinrich Schwabe published his discovery of the sunspot cycle.
On September 1, 1859, astronomers Richard Carrington and Richard Hodgson were independently observing the Sun. Before their eyes, a small part of its normally calm disk suddenly exploded in intensity, becoming far brighter. This burst of emission lasted for five minutes, and even to this day may have been the most luminous flare ever observed. Within a few hours of the observations of the flare, magnetometers (instruments that measure the strength and direction of a magnetic field) on Earth went crazy, registering huge fluctuations in the Earth’s magnetic field.
The Solar and Heliospheric Observatory detected this massive flare from the Sun on November 4, 2003. It was one of three huge flares that surprised scientists that day; no such string of events had ever been witnessed before. They marked one of the most active weeks for the Sun ever recorded.
SOHO (ESA & NASA)
They didn’t know it then, but at that moment the study of space weather was born.
They also couldn’t have known that the flare was caused when tangled magnetic field lines on the surface of the Sun suddenly realigned themselves. The energy stored in them was released like a bomb—the equivalent of 15 billion one-megaton nuclear weapons, or 10 percent of the total energy output of the Sun every second concentrated into one spot—hurling high-energy photons (particles of light) and subatomic particles both upward into space and downward onto the surface of the Sun. A typical flare from the Sun ejects billions of tons of subatomic particles outward at speeds that reach five million miles per hour—and in 2005, one extraordinary flare launched a blast of protons that reached the Earth in just fifteen minutes, indicating they were traveling at one-third the speed of light. These subatomic particles blast outward, generally straight out from the center of the flare. Because of this, the particles launched upward and outward from the flare are generally not a problem to us on Earth: they are focused enough that they usually miss us, causing no grief.
But along with the particles shot into space, a huge pulse of particles is shot down, onto the surface of the Sun. This heats the gas there tremendously, and creates an incredibly strong pulse of light. Now, that may not sound like a big problem; after all, how bad can light be?
Bad. But it depends on the kind of light.
What we call “visible light” is a narrow slice of a much wider range of electromagnetic radiation. Infrared light, for example, has less energy than visible light, and radio waves have less energy still. Ultraviolet (UV) light has more energy than the light we can see. Still higher-energy light is X-rays, and on up to gamma rays. UV, X-, and gamma rays are dangerous in large quantities. Each photon carries so much energy that it can radically alter any atom it hits, stripping off the atom’s electron, ionizing it.
Flares give off a lot of this kind of light. And unlike the particles of matter emitted in a solar flare, this light spreads out. A flare on the edge of the Sun’s disk will almost certainly miss us with its particles, but any flare anywhere on the visible surface of the Sun is a potential danger because of the high-energy light it emits.
Picture a solar flare on the Sun: the tangled magnetic field lines over a sunspot suddenly snap, rearranging themselves, and releasing their energy. They heat the local gas up to millions of degrees, and a blast of X-rays surges outward.
Traveling at the speed of light, the high-energy radiation takes a little over eight minutes to travel the 90 million or so miles to the Earth. When it does, it slams into everything in its way: satellites, astronauts, and even the Earth’s atmosphere.
On the
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