Explosions on the Sun that can affect our lives.

This blog is about major hiccups that occur on the surface of the sun, and how their radiation affects humanity on the earth. At the end is a discussion about deadly radiation bursts that have hit the earth about once every thousand years – and we are due for one.

Solar flares.
A solar flare is a flare-up of energy on the surface of the sun (the photosphere). The sun goes through an 11-year cycle called the sunspot cycle. The next sunspot maximum will be in 2024. Sunspots are dark spots that denote solar activity — more spots means more flares. Solar flares will reach an 11- year high in 2024 (the last high was in 2013).

When a solar flare goes off, bursts of radiation are shot out into space. The radiation can be radio waves, visible light, and ultraviolet. If it’s a strong flare, x-rays can be emitted and energetic particles such as protons and electrons too. Solar flares are powerful bursts of energy known to impact earth: electric power grids, navigation signals, radio communications, and they can pose risks to spacecraft and astronauts.

Spiral lines of force from sun’s magnetic field. Earth is at bottom right.

Except for the protons and electrons, Most of the radiation travels in a straight line through interplanetary space. Some of it may hit the earth and cause radio blackouts. A recent big solar flare on 14 December 2023 caused many radio upsets on airlines, especially those traveling close to the poles of the earth. The flare temporarily disrupted radio communication on Earth for a couple of hours, with multiple pilots reporting communication problems.

But protons and electrons emitted by a big solar flare don’t travel in a straight line because they are forced to follow the lines of magnetic force from the sun’s magnetism. The lines of force are curved like the water spray from a rotating lawn sprinkler. Believe it or not, I sent four years in graduate school studying how protons and electrons follow these magnetic lines of force that reach from the sun to the earth.

This was important to understand by NASA who were sending men on the Apollo series of missions to the moon. If a big solar flare went off in the wrong place on the sun, high-energy protons could arrive at earth within 8 minutes. If an astronaut were walking on the moon, he could get a lethal dose of radiation.

The Parker Solar Probe encounters wispy outer layers of the solar corona. Source: NASA.

The Parker solar probe.
This spacecraft is named after Eugene Parker, a scientist who first showed the magnetic lines of force were spirals. Its goal is to orbit very close to the sun, to understand some major mysteries about our own star. The following are several excerpts from an article by Marcia Dunn:
• The Parker Solar Probe, a spacecraft the size of a small car, was launched on 12 August 2018 from Cape Canaveral in Florida. During the seven-year mission, it will reach closer to the Sun than any other spacecraft before it.
• Its instruments are protected from the extreme heat and radiation by a revolutionary new carbon heat shield. The shield is capable of withstanding 2,500 degrees F (1,370 degrees C).
• Among the mysteries scientists hope to solve: Why is the corona almost 1 million degrees C and hundreds of times hotter than the surface of the sun, which is 6,000 degrees C? And why is the sun’s atmosphere continually expanding and accelerating, as Parker theorized about 60 years ago in 1958?
• A better understanding of the sun’s life-giving and sometimes violent nature could also enable earthlings to better protect satellites and astronauts in orbit, along with earth’s electrical power grids so vital to today’s technology-dependent society.

The Parker solar probe, on 24 December 2024, will race past the Sun at a speed of 435,000 mph – faster than any human-made object. And the probe will get closer to the sun than it, or any other spacecraft, has — just 4% of the Sun-Earth distance. It has made close passes before but never this close. The temperature on the heat shield will reach roughly 1400 C.

The main goal of the Parker solar probe is to explain the difference between the 6,000 C temperature at the photosphere, the sun’s surface, and the temperature in the corona, which is about 1 million C. This is opposite what’s expected because the corona lies way above the photosphere and normally would be much cooler. The corona has the spiky lines and loops that can be seen in a total eclipse when the photosphere is blotted out.

What in the world causes the extra heating in the corona? The best guess is plasma waves of some kind (the corona is a plasma) that transport energy outwards, like ocean waves carry energy to the beach and can knock a swimmer over.

A coronal mass ejection (CME) from the sun. If it crashes into earth’s magnetic field (at top right) it causes a geomagnetic storm. Source: US Geological Survey.

Geomagnetic storms.

Occasionally, a huge explosion, called a coronal mass ejection (CME), erupts from the sun, sending a rare deluge of particles into space. A CME is often associated with a big solar flare. The flare explodes releasing all sorts of radiation that zooms away and is seen 8 minutes later at the earth – based on the speed of light crossing the distance from sun to earth.

But the CME is like a lumbering elephant of intensified solar wind and magnetic fields fronted by a tremendous shock wave. It travels much slower arriving at earth typically two days after the solar flare.

In 1859, one of those explosions, called the Carrington event, made a direct hit on Earth, disrupting telegraph wires in America and Europe. If the same thing happened today, it could cause continent-wide blackouts, potentially requiring months or years to repair.

Even minor CMEs can have a major impact at earth. According to NOAA, “After a successful launch from Cape Canaveral, Florida in early February 2022, a minor geomagnetic storming caused 38 of 49 SpaceX Starlink satellites to fail to reach their final orbit, instead burning up during unplanned re-entry into Earth’s atmosphere.”

This article spells out the potential risk. “Large amounts of plasma or superheated matter bombarding the Earth can put electronics that are usually deemed safe or ‘grounded,’ like fiber optic cables, navigation systems, communication equipment, and even satellites, at risk.”

A CME often generates a visible aurora, such as the Northern Lights, that can be seen at lower latitudes than usual. I studied a few CME’s using satellite data from Los Alamos National Laboratory that showed cosmic ray protons and electrons sloshing back and forth, which provided evidence for loops of magnetic lines of force inside the CMEs.

Tree rings from Huon Pine tree (left panel) superimposed on image of the sun (right panel). Source: University of Queensland.

Tree ring radiation bursts.
The Carrington event in 1859 was the most intense geomagnetic storm in recorded history. But it pales when compared with Miyake events, when the earth has been hit by radiation up to 100 times more intense than Carrington. The Miyake events were discovered as radiation spikes in tree rings.

Six such events have been found across 10,000 years, so on average they occur once every thousand years. The most recent spikes occurred in 774 AD and 993 AD, so the earth is due for another burst of radiation. Astrophysicist Benjamin Pope of the University of Queensland in Australia said these spikes wouldn’t harm humans directly (presumably because they are de-energized when interacting with earth’s atmosphere), but they could cause incalculable damage to our radio and electronic systems – for months or longer.

The radiation spikes were observed in tree rings of Tasmania Huon Pines. The key evidence is radioactive carbon-14, that is caused by cosmic rays of solar or galactic origin impinging on earth’s atmosphere.

How long do these Miyake events last? In 663 BC one event lasted up to three years. In 5480 BC another one lasted a decade. The length of time is found directly from the width of intense radiation seen in the tree rings. Radiation spikes also occur in ice cores, and scientists are comparing the data against tree rings.

Dr Pope’s best guess is that the longer duration spikes may come from a series of outbursts from the Sun, which is plausible from what we know about the sun. But they might be caused by bursts of cosmic rays coming at earth from the galaxy.

Scientists aren’t certain of the cause of the Miyake radiation spikes, but if one happens in this lifetime, even if the cosmic rays won’t get to us and damage our cells, they may put Wi-fi and the Internet out for months and this would paralyze a lot of our economy…. a very scary thought.

The Gray Nomad. I wish you all the very best for the new year of 2024.
Your sun shall no more go down, nor shall your moon withdraw itself; for the Lord shall be your everlasting light, and the days of your mourning shall be ended.
[Isaiah chapter 60].

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5 months ago

Thank you Ian for this interesting blog post. Looks like humans are not in as much control as we would like to think. Wow, consider that.

5 months ago

Ian, I enjoyed your article but I don’t understand a lot of it.

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