When the maelstrom of super-heated gas that is the Sun’s surface ties itself in a knot, the results can be both unimaginably powerful and blindingly beautiful.
At the end of February, space weather enthusiasts were spoilt by the biggest solar flare of the year and one of the most impressive to be seen during this solar cycle by NASA’s Solar Dynamics Laboratory.
One of a Kind
Solar flares are a frequent feature of the Sun’s surface, but it is not often that a flare as brilliant as this ignites from the outer layers in a marvel of looping light and energy.
It was classified as an X4.9 (X-Class denotes the most intense flares). The scale is based on a multiplication scheme in that X2 is twice as intense as X1, and X3 is three times the intensity etc.
Luckily, the main impact of this particular event was a significant Aurora Borealis (or “Northern Lights”) event, dancing on our ionosphere to treat those at high latitudes to a night time light show in the starry sky.
However, in a “solar system wide” shooting gallery, with 360 degrees of space at which to aim, the main target of insurance exposure in our cosmic portfolio is, of course, Earth. What if our planet was in the firing line?
How Does it Effect Earth?
These monstrous flares can have a broad impact on Earth as many of our modern technologies are vulnerable to extremes of space weather.
X-Class flares are often followed by long lasting solar radiation storms continuing after the event. Strong geomagnetic storms will also occur if a subsequent Coronal Mass Ejection, (or CME, often associated with solar flares) hits our planet.
Infrastructure can be impacted in a number of ways. Electrical currents driven along the Earth’s surface can lead to disruption of power grids in the form of blown transformers or damage to power lines through a higher incidence of electrical arcing.
Changes in the ionosphere can create interference with high-frequency radio communications and GPS systems.
Transpolar airlines routes can suffer from reduced radio communications during polar cap absorption events as the Earth’s magnetic field draws solar protons to the poles.
And of course spacecraft and satellite equipment can be exposed to energetic particles which can cause a whole host of difficulties including damage to critical electronics, degradation of solar arrays, and malfunctioning of optical systems such as imagers and star trackers.
The largest solar flare recorded since satellites began measuring them in 1976 was classified as an X28, so roughly 6 times the intensity of the recent event, and occurred on the 4th of November in 2003.
Luckily this storm was also facing in a different direction while rotating away from Earth. There have been a few that have erupted with Earth in their sights (information here adapted from various NASA space weather sites):
September 1959 – Caused disruption to the telegraph service
August 1972 – Near miss on a manned space mission. Had the event on August 7th happened during one of the Apollo 16 and Apollo 17 missions instead of in between them, the astronauts would have been exposed to a dose of energetic solar particles outside of the Earth’s protective magnetic field, and could have been left in a life threatening situation
March 1989 – Caused the collapse of the Hydro-Québec power network through geomagnetically induced currents which led to a transformer failure and consequently a general blackout that lasted 9 hours and affected over 6 million people. The CME that caused this erupted from the Sun’s surface 4 days earlier
January 1994 – Caused outages of two Canadian telecommunications satellites. Recovery took 6 months and cost $50 to $70 million
Current day – Diversions of airliners that take polar routes where satellite communications cannot be used. Solar flares can lead to interference with the high-frequency radio communications that these routes rely upon and so when there is a forecast for possible solar impacts, these routes are diverted.
An example occurred in January 2005 where 26 United Airlines flights were diverted to non-polar and less-than optimal flight paths during several days of disturbances.
The threat of solar storms exists. The impacts they can have on infrastructure and the consequent cost for repair and recovery, not to mention loss due to business interruption require attention and forewarning.
To this end, space weather desks around the world are monitoring the Sun and are able to give alerts for when an event is on the way, hopefully mitigating damages or loss.
Even though we are more vulnerable than ever due increased exposure and reliance on susceptible infrastructure, we are also more prepared than ever to mitigate geomagnetic disaster.
Data and models are available through NASA’s Heliophysics Division (among other sources) for academic, civil and industrial use to allow us to learn more about this beautiful yet potentially disruptive risk.
So how does solar weather influence our weather here on Earth? It’s all about energy balance. Solar activity has a spectrum of periodic variations, the main one of which is an eleven-year oscillatory cycle linked to sun spot counts.
When there is a high level of activity we also see more solar flares and CME events.
Since the energy from the Sun is ultimately the driver of our weather and climate systems, any variation in this solar output should be reflected in our efforts to understand or model the depth of our atmosphere from troposphere to ionosphere – and it is.
In climate modelling the term “Radiative Forcing” describes the element of a climate model that represents the incoming solar energy and its effect on the atmosphere.
The variability of incoming solar energy is observable and over the last three cycles amounts to a change of roughly 0.1% of the solar output at the edge of our atmosphere (roughly averaging at 1366 Watts per square metre).
This fluctuation is a small component and has undergone much scientific study. Generally it is not considered to be a major influence on the climate system in the short term.
However, this solar variation, along with volcanic activity, is considered to influence our climate on some longer time scales, and may have contributed to the Little Ice Age, but it is also thought to be too weak to have driven recent climate change.
Further research into incoming UV variation (a range of + or – 3%) or variations in cosmic rays may unlock some more influential clues to unraveling the climate system and its tangle of oscillations and fluctuations.