- he sunspot quickly evolved into an unstable configuration and could lead to solar flares, Nasa warns
- The agency’s Solar Dynamics Observatory watched it form in less than 48 hours over Tuesday and Wednesday
A giant sunspot that is at least six times the diameter of Earth has formed on the Sun in less than 48 hours, Nasa has announced.
Sunspots are dark spots on the surface of the Sun which appear as turbulent magnetic fields in its surface rearrange and realign.
The massive sunspot, which formed over the course of Tuesday and Wednesday, quickly evolved into an unstable configuration, and could lead to solar flares, which can interrupt our radio communications.
Nasa scientists spotted the huge sunspot forming through instruments on the agency’s Solar Dynamics Observatory, one of several spacecraft that monitor the Sun’s weather.
‘Over the course of February 19-20, 2013, scientists watched a giant sunspot form in under 48 hours,’ said Karen Fox, a spokesman for Nasa.
‘It has grown to over six Earth diameters across but its full extent is hard to judge since the spot lies on a sphere not a flat disk.’
The sunspot identified by Nasa is formed of several dark blemishes on the surface on the Sun which have evolved rapidly over the past couple of days.
NASA’S SUN WATCHER: THE SOLAR DYNAMICS OBSERVATORY
The Solar Dynamics Observatory contains a suite of instruments that will provide observations leading to a more complete understanding of the solar dynamics that drive variability in the Earth’s environment.
This set of instruments:
- Measures the extreme ultraviolet spectral irradiance of the Sun at a rapid cadence
- Measures the Doppler shifts due to oscillation velocities over the entire visible disk
- Makes high-resolution measurements of the longitudinal and vector magnetic field over the entire visible disk
- Makes images of the chromosphere and inner corona at several temperatures at a rapid cadence
- Makes those measurements over a significant portion of a solar cycle to capture the solar variations that may exist in different time periods of a solar cycle
Sunspots are caused by intense magnetic activity and are actually cooler than the rest of the Sun, which leaves them clearly visible as dark spots in the photosphere.
In reality, if the sunspot were isolated from the surrounding photosphere it would be brighter than an electric arc.
Ms Fox added: ‘The spot quickly evolved into what’s called a delta region, in which the lighter areas around the sunspot, the penumbra, exhibit magnetic fields that point in the opposite direction of those fields in the center, dark area.
‘This is a fairly unstable configuration that scientists know can lead to eruptions of radiation on the sun called solar flares.’
The observation comes as the Sun is gearing up for the most active phase of its 11-year solar cycle.
The Sun’s magnetic field lines are the most distorted at this time due to the magnetic field on the solar equator rotating at a slightly faster pace than at the solar poles.
This causes large numbers of sunspots appear, and the Sun’s irradiance output grows by about 0.1 per cent.
The increased energy output of solar maxima can impact global climate and recent studies have shown some correlation with regional weather patterns.
The solar cycle takes an average of about 11 years to go from one solar maximum to the next, with an observed variation in duration of 9 to 14 years for any given solar cycle.
Large solar flares often occur during a maximum. For example, the Solar storm of 1859 struck the Earth with such intensity the northern lights could be seen as far south as Rome.
The last solar maximum was in 2000. In 2006 NASA initially expected a solar maximum in 2010 or 2011, and thought that it could be the strongest since 1958.
However, more recent projections say the maximum should arrive in autumn of 2013 and be the smallest sunspot cycle since 1906.