Related topics: magnetic field · earth · sun · nasa

Solar activity reconstructed over a millennium

An international team of researchers led by ETH Zurich has reconstructed solar activity back to the year 969 using measurements of radioactive carbon in tree rings. Those results help scientists to better understand the dynamics ...

The U.S. Postal Service to issue NASA sun science forever stamps

NASA's images of the sun's dynamic and dazzling beauty have captivated the attention of millions. In 2021, the US Postal Service is showcasing the sun's many faces with a series of sun Science forever stamps that show images ...

Coronal holes during the solar maximum

Sunspots were first seen by Galileo, and in the eighteenth century Rudolf Wolf concluded from his study of previous observations that there was a roughly eleven-year solar cycle of activity. In 1919 the astronomer George ...

Solar cycle 25: The sun wakes up

The sun has entered its 25th solar cycle and is about to wake up. For the last few years our star has been pretty sleepy, with few sunspots, bright flares or massive ejections of magnetized plasma emanating from its surface. ...

Solar cycle 25 has begun

In the past one and a half years, the sun has been rather dull: hardly a sunspot covered its surface, hardly a solar flare hurled radiation and particles into space. As observational data now show, for the last nine months ...

Spinning black hole powers jet by magnetic flux

Black holes are at the center of almost all galaxies that have been studied so far. They have an unimaginably large mass and therefore attract matter, gas and even light. But they can also emit matter in the form of plasma ...

Breakthrough method for predicting solar storms

Extensive power outages and satellite blackouts that affect air travel and the internet are some of the potential consequences of massive solar storms. These storms are believed to be caused by the release of enormous amounts ...

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Solar variation

Solar variations are changes in the amount of solar radiation emitted by the Sun. There are periodic components to these variations, the principal one being the 11-year solar cycle (or sunspot cycle), as well as aperiodic fluctuations. Solar activity has been measured via satellites during recent decades and through 'proxy' variables in prior times. Climate scientists are interested in understanding what, if any, effect variations in solar activity have on the Earth. Effects on the earth caused by solar activity are called "solar forcing".

The variations in total solar irradiance remained at or below the threshold of detectability until the satellite era, although the small fraction in ultra-violet wavelengths varies by a few percent. Total solar output is now measured to vary (over the last three 11-year sunspot cycles) by approximately 0.1% or about 1.3 W/m² peak-to-trough during the 11 year sunspot cycle. The amount of solar radiation received at the outer surface of Earth's atmosphere averages 1,366 watts per square meter (W/m²). There are no direct measurements of the longer-term variation and interpretations of proxy measures of variations differ. On the low side North et al. report results suggesting ~ 0.1% variation over the last 2,000 years. Others suggest the change has been ~ 0.2% increase in solar irradiance just since the 17th century. The combination of solar variation and volcanic effects are likely to have contributed to climate change, for example during the Maunder Minimum. Apart from solar brightness variations, more subtle solar magnetic activity influences on climate from cosmic rays or the Sun's ultraviolet radiation cannot be excluded although confirmation is not at hand since physical models for such effects are still too poorly developed.

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