Solar minimum
Encyclopedia
Solar minimum is the period of least solar activity in the solar cycle
of the sun
. During this time, sunspot
and solar flare
activity diminishes, and often does not occur for days at a time. The date of the minimum is described by a smoothed average over 12 months of sunspot
activity, so identifying the date of the solar minimum usually can only happen 6 months after the minimum takes place.
Solar minimum is contrasted with the solar maximum
, where there may be hundreds of sunspots.
At a solar minimum, there are fewer sunspots and solar flares subside. Sometimes, days or weeks go by without a spot. It is a safer time to travel through space, but a less interesting time to watch polar skies.
) for more accurate predictions and have confidence in the forecast based upon a series of test runs with the newly developed model simulating the strength of the past eight solar cycles with more than 98% accuracy.
During 2008-2009 NASA scientists noted that the Sun is undergoing a "deep solar minimum," stating: "There were no sunspots observed on 266 of [2008's] 366 days (73%). Prompted by these numbers, some observers suggested that the solar cycle had hit bottom in 2008. Sunspot counts for 2009 dropped even lower. As of September 14, 2009 there were no sunspots on 206 of the year's 257 days (80%). It adds up to one inescapable conclusion: "We're experiencing a very deep solar minimum," says solar physicist Dean Pesnell of the Goddard Space Flight Center. "This is the quietest sun we've seen in almost a century," agrees sunspot expert David Hathaway of the National Space Science and Technology Center NASA/Marshall Space Flight Center. It's a natural part of the sunspot cycle, discovered by German astronomer Heinrich Schwabe in the mid-19th century. A "clockwork pattern" that has held true for more than 200 years.
Solar cycle
The solar cycle, or the solar magnetic activity cycle, is a periodic change in the amount of irradiation from the Sun that is experienced on Earth. It has a period of about 11 years, and is one component of solar variation, the other being aperiodic fluctuations. Solar variation causes changes in...
of the sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. During this time, sunspot
Sunspot
Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature....
and solar flare
Solar flare
A solar flare is a sudden brightening observed over the Sun surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy . The flare ejects clouds of electrons, ions, and atoms through the corona into space. These clouds typically reach Earth a day...
activity diminishes, and often does not occur for days at a time. The date of the minimum is described by a smoothed average over 12 months of sunspot
Sunspot
Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature....
activity, so identifying the date of the solar minimum usually can only happen 6 months after the minimum takes place.
Solar minimum is contrasted with the solar maximum
Solar maximum
Solar maximum or solar max is the period of greatest solar activity in the solar cycle of the sun. During solar maximum, sunspots appear....
, where there may be hundreds of sunspots.
Solar minimum and solar maximum
Solar minimums and maximums are the two extremes of the sun's 11-year activity cycle. At a maximum, the sun is peppered with sunspots, solar flares erupt, and the sun hurls billion-ton clouds of electrified gas into space. It's a good time for sky watchers who enjoy auroras, but not so good for astronauts who have to be wary of radiation storms. Power outages, satellite malfunction and communication disruptions, and GPS receiver malfunctions are just a few of the things that can happen during a solar maximum.At a solar minimum, there are fewer sunspots and solar flares subside. Sometimes, days or weeks go by without a spot. It is a safer time to travel through space, but a less interesting time to watch polar skies.
Predicting Solar Minimum Cycles
Predicting solar activity is very difficult because solar activity is a non-linear phenomenon and hence cannot be predicted very easily. Solar minimum is characterized by a period of minimum solar activity with few, if any, sunspots. Generally, this is the safest time for astronauts to do their missions due to an associated decrease in solar radiation. Three NASA scientists were better able to predict solar cycles (solar minimums and solar maximums) using a simple function with four parameters, which then led the ability to discover the duration of these solar cycles. Scientists from the National Center for Atmospheric Research (NCAR) also developed a computer model of solar dynamics (Solar dynamoSolar dynamo
The solar dynamo is the physical process that generates the Sun's magnetic field. The Sun is permeated by an overall dipole magnetic field, as are many other celestial bodies such as the Earth. The dipole field is produced by a circular electric current flowing deep within the star, following...
) for more accurate predictions and have confidence in the forecast based upon a series of test runs with the newly developed model simulating the strength of the past eight solar cycles with more than 98% accuracy.
During 2008-2009 NASA scientists noted that the Sun is undergoing a "deep solar minimum," stating: "There were no sunspots observed on 266 of [2008's] 366 days (73%). Prompted by these numbers, some observers suggested that the solar cycle had hit bottom in 2008. Sunspot counts for 2009 dropped even lower. As of September 14, 2009 there were no sunspots on 206 of the year's 257 days (80%). It adds up to one inescapable conclusion: "We're experiencing a very deep solar minimum," says solar physicist Dean Pesnell of the Goddard Space Flight Center. "This is the quietest sun we've seen in almost a century," agrees sunspot expert David Hathaway of the National Space Science and Technology Center NASA/Marshall Space Flight Center. It's a natural part of the sunspot cycle, discovered by German astronomer Heinrich Schwabe in the mid-19th century. A "clockwork pattern" that has held true for more than 200 years.
See also
- List of solar cycles
- Maunder MinimumMaunder MinimumThe Maunder Minimum is the name used for the period roughly spanning 1645 to 1715 when sunspots became exceedingly rare, as noted by solar observers of the time....
- Solar cycleSolar cycleThe solar cycle, or the solar magnetic activity cycle, is a periodic change in the amount of irradiation from the Sun that is experienced on Earth. It has a period of about 11 years, and is one component of solar variation, the other being aperiodic fluctuations. Solar variation causes changes in...
- Solar cycle 24Solar Cycle 24Solar Cycle 24 is the 24th solar cycle since 1755, when recording of solar sunspot activity began. It is the current solar cycle, and began on . The cycle continues to fall below predictions and is currently exhibiting 50% lower sunspot activity than predicted in May 2009.-Predictions:It is...
- Solar maximumSolar maximumSolar maximum or solar max is the period of greatest solar activity in the solar cycle of the sun. During solar maximum, sunspots appear....