Space Weather and the Effects it has on Earth: An Overview

Space weather has been in the news a great deal lately, and today, the day asteroid DX110 makes a close pass by the Earth seems a good day to write an article that will hopefully answer many of the questions that have been asked regarding space weather and its effects on the Earth.

The Solar Cycle

Our star, the Sun, is a roiling ball of gas that has a very strong magnetic field. The magnetic flux that rises to the surface varies over time on roughly an 11 year cycle, the solar cycle.

It’s sometimes called the sun spot cycle as there are times when there are many more sunspots than usual. This is the sunspot maximum, and conversely the time when there are few or even no sunspots, is the sunspot minimum. The solar cycles are numbered, the one we are in now is Cycle 24. The duration and strength of a sunspot cycle can be affected by the cycle that preceded it. It’s a little to complex to go into in this article, but you can read more here.

Sunspots

Sunspots appear in localized areas of very high magnetism. They appear darker because they are several thousand degrees cooler than the gas surrounding them. Gauss is a measure of magnetism, and sunspots need a minimum of 1500 Gauss to form at all. If the Gauss is not high enough there are no sunspots. They move across the sun disc before moving out of site and usually degrading. Rarely, as with sunspot AR1944, the spot survives. AR1944 became AR1967 when it reappeared, and it is now on its third incarnation known as AR1990.

Solar flares

A solar flare is a sudden, rapid, intense increase in brightness in a given area of the sun, usually one where sunspots are present.

On the morning of September 1, 1859, amateur astrologer Richard Carrington ascended into the private observatory attached to his country estate outside of London. After cranking open the dome’s shutter to reveal the clear blue sky, he pointed his brass telescope toward the sun and began to sketch a cluster of enormous dark spots that freckled its surface. Suddenly, Carrington spotted what he described as “two patches of intensely bright and white light” erupting from the sunspots. Five minutes later the fireballs vanished, but within hours their impact would be felt across the globe.

That night, telegraph communications around the world began to fail; there were reports of sparks showering from telegraph machines, shocking operators and setting papers ablaze. All over the planet, colorful auroras illuminated the nighttime skies, glowing so brightly that birds began to chirp and laborers started their daily chores, believing the sun had begun rising. Some thought the end of the world was at hand, but Carrington’s naked eyes had spotted the true cause for the bizarre happenings: a massive solar flare with the energy of 10 billion atomic bombs. The flare spewed electrified gas and subatomic particles toward Earth, and the resulting geomagnetic storm—dubbed the “Carrington Event”—was the largest on record to have struck the planet . (source)

Flares are split into classifications, A,B,C,M,X. The scale within each classification is logarithmic meaning, for example, an X2 flare is twice as powerful as an X1 flare and four times more powerful than an M5 flare. (source)

The “electrified gas and subatomic particles” referred to above changed status as they passed through the corona of the sun.

Coronal Mass Ejections (CME’s)

Sunspots have magnetic fields, and when the field becomes unstable it can collapse. This shows as a sudden brightening, the flare itself. Sometimes a collapse doesn’t occur and a flare comes from an active region (a sunspot) that hasn’t collapsed its field. The resulting explosion shoots up to the corona, a gaseous layer around the sun. The corona is not uniform, but has loops in it that connect to active areas, sunspot areas below it.

When the flare shoots forth, the gaseous loops in the corona are forced outwards like a huge balloon at more than a million miles an hour. This is a coronal mass ejection, or CME for short. Not all flares will have the power to get out through the corona, and therefore those flares will not produce a coronal mass ejection.

Coronal Holes

Pretty regularly a hole forms in the corona and not surprisingly these are called coronal holes. A hole in this fluid like, highly rarefied gas layer, allows the solar wind, created by the volatile star beneath, to escape at a much faster speed than where there is no hole, rather like the air gushing from a balloon as opposed to leaking slowly out of it.

The solar wind

This solar wind blows at around a million miles an hour, if they intercept the Earth they push up against and excite the Earths magnetic field, the magnetosphere, and cause disturbances in the field which leads to the beautiful charged gas shows we call the Aurora Borealis, the Northern lights, and the Aurora Australis, the Southern lights.

Electromagnetic pulse (EMP)

An electromagnetic pulse (EMP) is a burst of electromagnetic energy produced by a nuclear explosion in the atmosphere. The Sun is a giant nuclear reactor and exceptionally strong flares, like the one during the Carrington event, can produce EMP bursts.

Meteoroids/Meteors/Meterorites

Small chunks of rock, and even the remnants of comets sometimes fail to totally burn up in the Earth’s atmosphere. Items on a collision course with our planet are called meteoroids. When they enter the earths atmosphere their name changes to meteors, and if they actually make it to the surface they are called meteorites.

What we call shooting stars are actually small bits of debris burning up in the atmosphere.

The Earth has been hit many times by meteorites, Meteor Crater and the equally impressive Barringer Crater, both in Arizona, are typical examples of impact sites. Luckily Arizona was uninhabited at the time of these impacts. The shockwave would have sent a pressure wave out for miles that would have destroyed everything in its path. Fires would have been likely as any ejecta would have been super heated due to the force of the impact. The hot particles would have fallen back starting fires when they came into contact with tress or other combustibles.

Asteroids

Asteroids can range from the size of pebbles to 600 miles in diameter as in the case of Ceres discovered in 1801.

Near Earth Asteroids (NEA) are divided into classes:

Amors: Asteroids which cross Mars’ orbit but do not quite reach the orbit of Earth. Eros — target of the NEAR mission — is a typical Amor.

Apollos: Asteroids which cross Earth’s orbit with a period greater than 1 year. Geographos represents the Apollos.

Atens: Asteroids which cross Earth’s orbit with a period less than 1 year. Ra-Shalom is a typical Aten.

Due to their speed, asteroids punch above their weight.

On June 30, 1908 a small asteroid, 330 feet (100 meters) in diameter, exploded over the remote region of Tunguska in Siberia, devastating more than half a million acres of forest.

Gamma Ray Burst

A gamma ray burst is thought to come from a dying star, a supernova, billions of miles away from us. Scientists disagree on whether or not the Earth, or life on Earth would survive such an event. Gamma ray bursts put out more energy in a split second than our Sun generates over its entire life. Scientists see the echoes of these supermassive explosions, but can only analyze data from those that explode when facing the instruments.

The effects these things have on Earth

The effects of space weather on Earth is very varied, but there is still a great deal for scientists to work out before we have all the answers.

There are historical documents that help scientists see patterns in data that has been collected since the invention of the telescope. This data gives a good starting point for future studies.

One of the most studied areas is the effects of sunspot numbers on climate. By correlating the documentation, scientists have worked out that solar cycles with low sunspot activity appear to show a cooler weather pattern on Earth.

The Dalton Minimum and the Maunder Minimum are the two most often mentioned, but there were many others, the Sporer minimum for example.

NASA has admitted that low activity cycles leads to cooler temperatures, but the government has still failed to raise awareness of the issues a cooling climate can bring.

The work of scientists such as Livingston and Penn and Professor Don Easterbrook leaves little doubt of the effects sunspots, or rather the lack of them, can have on Earth’s climate.

Flares can produce strong coronal mass ejections, and even worse, electromagnetic pulses. Both of these events are capable of causing a disturbance to the magnetosphere that protects the Earth.

In the case of strong flares, serious damage to infrastructure can be caused. In the case of an extreme EMP event, devastation will be caused.

The 1989 event that hit Canada is a good example of what can happen. It should be remembered that the 1989 space storm was nowhere near as strong as the 1859 storm that Carrington witnessed.

Lesser events can cause radio blackouts and affect GPS devices. Astronauts and air cabin crew can suffer higher than normal radiation doses during periods of high solar activity.

Meteorites and asteroids can make very big holes even if they are relatively small. Either of them hitting a city or town would have an extremely bad outcome for people in the area.

TV135, discovered last year by Ukranian astronomers, is a 1,300 feet wide lump of rock that will pass VERY close to Earth in 2032. With its weight and speed, IF it hit, and there’s a 1 in 63,000 chance that it will, it would cause regional devastation. Damage would be widespread from the pressure wave and the debris thrown up, and the impact crater would be a few city blocks across.

Finally, Gamma ray bursts…nobody knows. Some scientists say we would fry on the spot, others say we wouldn’t. There’s not enough information yet to call it one way or the other.