Current Events

  • Irish Chronicles Document Links Between Volcanoes and Weather
    A study of over 40,000 written entries in Irish Annals and ice core measurements shows a strong corr...Read more

    x

    Irish Chronicles Document Links Between Volcanoes and Weather

    A study of over 40,000 written entries in Irish Annals and ice core measurements shows a strong correlation between the occurrence of volcanic eruptions and extreme cold weather in Ireland over a 1200 year period. Data analyzed in this study cover the period from 431 to 1649, during which time up to 48 volcanic eruptions are identified in Greenland ice core records through deposition of volcanic sulfate in annual layers of ice. You can find the study (open access), published on 6 June 2013 in IOP Publishing's journal Environmental Research Letters, at http://iopscience.iop.org/1748-9326/8/2/024035/article. Find out more about how volcanoes can influence climate.
  • EF-5 Tornado in El Reno, Oklahoma Widest Ever Recorded in US
    The EF-5 tornado that hit El Reno, Oklahoma on May 31st was the widest ever recorded in the US, acco...Read more

    x

    EF-5 Tornado in El Reno, Oklahoma Widest Ever Recorded in US

    The EF-5 tornado that hit El Reno, Oklahoma on May 31st was the widest ever recorded in the US, according to the National Weather Service in Norman Oklahoma. The tornado, which remained on the ground for 40 minutes and reached 2.6 miles across (4.2 km), took the lives of 18 people including storm chasers Tim Samaras, Paul Samaras and Carl Young. For more information on the tornado, visit http://ow.ly/i/2hfDG.
  • Atmospheric CO2 Level Tops 400 ppm
    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm rep...Read more

    x

    Atmospheric CO2 Level Tops 400 ppm

    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm repeatedly. Daily levels of CO2 can vary due to weather, and there are seasonal trends as well. The level of atmospheric greenhouse gases continues to increase, now over 120 ppm since the Industrial Revolution began. For more on the Keeling Curve, see http://keelingcurve.ucsd.edu/. Find out more about greenhouse gases and warming.
These images show two Jupiter-sized sunspot groups on the face of the Sun (left) and an extreme close-up of a different, smaller sunspot group (right). The lefthand image was taken on Oct. 24, 2003 by the SOHO (Solar & Heliospheric Observatory) spacecraft. The righthand image was taken on July 15, 2002 by the Swedish 1-m Solar Telescope on the island of La Palma off the western coast of Africa. The central dark part of the large sunspot in the middle of the righthand image is about 14,000 km (8,700 miles) across... slightly larger than Earth!
Click on image for full size
Images courtesy SOHO (NASA & ESA) and the Royal Swedish Academy of Sciences.

Related links:

History of Sunspot Observations

The Sunspot Cycle

Sizes of Sunspots

Sunspots and Magnetic Fields

Movie: Journey Beneath a Sunspot

Do Changes in Sunspot Numbers Affect Weather and Climate on Earth?

Starspots

Animation: Rotating Sun with Sunspots

Sunspot Jigsaw Puzzle

Activity: Graphing Sunspot Cycles

Activity: Tracking the Motion of an Active Sunspot Region

Activity: Plotting Locations of Active Regions on the Sun

Movie: Supercomputer Models Help Scientists Understand Sunspots

Sunspots

Sunspots are dark, planet-sized regions that appear on the "surface" of the Sun. Sunspots are "dark" because they are cooler than their surroundings. A large sunspot might have a central temperature of 4,000 K (about 3,700° C or 6,700° F), much lower than the 5,800 K (about 5,500° C or 10,000° F) temperature of the adjacent photosphere. Sunspots are only dark in contrast to the bright face of the Sun. If you could cut an average sunspot out of the Sun and place it elsewhere in the night sky, it would be about as bright as a full moon. Sunspots have a lighter outer section called the penumbra, and a darker central region named the umbra.

Sunspots are caused by disturbances in the Sun's magnetic field welling up to the photosphere, the Sun's visible "surface". The powerful magnetic fields in the vicinity of sunspots produce active regions on the Sun, which in turn frequently spawn disturbances such as solar flares and Coronal Mass Ejections (CMEs). Because sunspots are associated with solar activity, space weather forecasters track these features in order to help predict outbursts of "solar storms".

Sunspots form over periods lasting from days to weeks, and can persist for weeks or even months before dissipating. The average number of spots visible on the face of the Sun is not constant, but varies in a multi-year cycle. Historical records of sunspot counts, which go back hundreds of years, verify that this sunspot cycle has an average period of roughly eleven years.

Our Sun isn't the only star with spots. In recent years, astronomers have been able to detect "starspots" - "sunspots" on other stars.

Last modified January 19, 2010 by Randy Russell.

Shop Windows to the Universe Science Store!

Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store.

Windows to the Universe Community

News

Opportunities

Upcoming W2U Events
Join Today - Benefits,
No Ads!
Special Offers for Teachers
Member Benefits
Teacher Newsletter
Partnership Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

The Photosphere - the "Surface" of the Sun

Most of the energy we receive from the Sun is the visible (white) light emitted from the photosphere. The photosphere is one of the coolest regions of the Sun (6000 K), so only a small fraction (0.1%)...more

The Sun's Magnetic Field

The Sun has a very large and very complex magnetic field. The magnetic field at an average place on the Sun is around 1 Gauss, about twice as strong as the average field on the surface of Earth (around...more

Sunspots and Magnetic Fields

Sunspots are caused by extremely strong, localized magnetic fields on the Sun. "Jet streams" of plasma that form deep within the Sun's convective zone produce powerful magnetic fields. When these loops...more

Active Regions on the Sun

An active region on the Sun is an area with an especially strong magnetic field. Sunspots frequently form in active regions. Active regions appear bright in X-ray and ultraviolet images. Solar activity,...more

Starspots

In recent years astronomers have become able to detect "starspots" on distant stars! Like the sunspots that frequently dot the "surface" of the nearest star, our Sun, starspots are relatively cool, dark...more

Ulysses Going Strong During Solar Maximum

The Ulysses space probe has begun to investigate the Sun during solar maximum. In September of 2000, Ulysses began to creep around the underside of the Sun. Ulysses has passed this way before, but during...more

Maunder's Butterfly Diagram

Throughout the solar_cycle, the latitude of sunspot occurrence varies with an interesting pattern. The plot on the left shows the latitude of sunspot occurence versus time (in years). Sunspots are typically...more

Shop Windows to the Universe

Arches National Park Geology Tour provides an extensive, visually rich description of the geology of Arches, by Deborah Ragland, Ph.D. See our DVD collection.

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF