1. What is a solar flare?

We think the energy for a solar flare comes from the magnetic energy associated with strong fields on the Sun.- JK

2. Does ALL solar activity impact Earth? Why or why not?

Some activity, like mass ejections, are directional. Earth may not be in the path of a particular ejection so all activity does not affect Earth. -JK

3. How do solar flares reach Earth?

Big ejections from the Sun can be 1-10 billion tonnes, moving at 400-1000 km/sec (approximately 1-2 million mph) and take more than a day to pass Earth, after the sudden onset (often a leading-edge shock wave)

4. How strong is solar wind (compared to wind on Earth)?

Solar sails are still a theoretical concept--there aren't any in use today. They would sail not on the solar wind but on the photon (light) pressure from the sun.

5. Have scientists seen changes in the intensity of space weather?

At present, we are in the increasing phase of Cycle 23, which began in October 1996 and is expected to peak sometime during the year 2000. SWPC scientists have noted a steady increase in the number of sunspot groups and solar flares, as well as other space weather occurrences like solar proton events and a rising 10.7 cm solar radio flux. We've had about a dozen episodes of intense space weather so far this cycle and we expect to see many more as Cycle 23 continues.-NC

6. What are sunspots and how do they relate to space weather?

The magnetic field in sunspots stores energy that is released in solar flares. As a result, flares usually occur in a cycle that mimics the eleven-year sunspot cycle. Other forms of space weather such as geomagnetic storms and proton radiation showers follow a similar cycle. Sunspots usually occur in groups-usually as simple pairs-but at times in complicated arrangements with many spots and complex shapes. These unusual regions most often produce solar flares. Space weather forecasters use the complexity and shapes of sunspots to make flare forecasts-the more complex the groups of spots, the more likely a flare will occur. -GH

7. What is the solar max and solar min?

At solar minimum, the sun may go many days with no spots visible. At maximum, there may be several hundred spots on any day.-GH

8. What are the northern lights and are they related to space weather?

When the sun is active, it often produces mass ejections that interact with Earth's magnetic field. Electric currents begin to flow in the upper atmosphere, and these currents produce the aurora borealis, which occurs almost simultaneously around both the north and south poles.-GH

9. Why are some regions on the Sun more active than others?

Because the sun is made up of gases and because it rotates once every approximately 27 days around its north-south axis, the regions around the equator tend to rotate faster than the areas near the poles. This differential rotation drives the mass motions described above.-GH

10. How do you forecast space weather?

A good space weather forecast begins with a thorough analysis. SWPC forecasters analyze near-real-time ground- and space-based observations to assess the current state of the solar-geophysical environment (from the Sun to the Earth and points in between). Space weather forecasters also analyze the 27-day recurrent pattern of solar activity. Based on a thorough analysis of current conditions, comparing these conditions to past situations, and using numerical models similar to weather models, forecasters are able to predict space weather on times scales of hours to weeks.-NC

11. Why is forecasting space weather important?

Some of the specific effects of space weather on Earth systems include interference with short wave radio propagation, problems with electric power grids, the decay of satellite orbits, and radiation hazard for satellites and for astronauts during some phases of space missions.-GH

12. When do the effects of space weather show up?

Flares (sudden brightenings) affect the ionosphere immediately, with adverse effects upon communications and radio navigation (GPS and LORAN). Accompanying radio bursts from the Sun are expected to exceed cell phone system noise tolerances 2 - 3 times per solar cycle.

Solar energetic particles arrive in 20 minutes to several hours, threatening the electronics of spacecraft and unprotected astronauts, as they rise to 10,000 times the quiet background flux.

Ejected bulk plasma and its pervading magnetic field arrive in 30 - 72 hours (depending upon initial speed and deceleration) setting off a geomagnetic storm, causing currents to flow in the magnetosphere and particles to be energized. The currents cause atmospheric heating and increased drag for satellite operators; they also induce voltages and currents in long conductors at ground level, adversely affecting pipelines and electric power grids. The energetic particles cause the northern lights, as well as surface and deep dielectric charging of spacecraft; subsequent electrostatic discharge of the excess charge build-up can damage spacecraft electronics. The ionosphere departs from its normal state, due to the currents and the energetic particles, thereby adversely affecting communications and radionavigation.

Rayleigh-Taylor instability often occurs in tropical latitudes, causing rising bubbles to ascend out of the top of the ionosphere and substantially distorting the normal layering. This causes radio beams propagating through the rising columns to suffer up to 30 dB of scintillation; GPS receivers lose lock and communication signals break up as a result.-EH

13. How long have scientists known about space weather?

Space weather is noticed mostly by its effects on Earth. After a great solar flare in 1959, telegraph operators discovered that currents from the intense aurora borealis was flowing through their systems, causing their telegraph keys to melt and stick in position. During World War II, the new invention of radar failed whenever the space weather activity was high. Comet tails that curved and pointed way from the sun showed that a solar wind, a part of space weather, was always blowing out through the solar system. When police cars in San Francisco tried to talk to their dispatchers, dispatchers in Minneapolis answered (reference: The Northern Light, A. Brekke, A. Egeland, Springer-Verlag, New York. 1983). Plans for revisiting the Hubbell Telescope in orbit and boosting it high enough that it will not fall to Earth are driven by space weather. When space weather is high, the orbit decays more rapidly and booster missions must be flown more often.-GH

14. What is the role of the Space Weather Prediction Center?

The role of the Space Weather Prediction Center is to gather, in real time, all the available data that describes space weather. From this, space weather forecasters form a picture of the environment from the Sun to Earth. With this information, alerts, warnings, and forecasts are prepared by Space Weather Prediction Center for users that may be affected.-GH

15. How do you monitor events on the sun?

SWPC scientists and technicians utilize a variety of ground- and space-based sensors and imaging systems to view activity at various depths in the solar atmosphere. A worldwide network of USAF-sponsored optical observatories also provides space weather forecasters with detailed plain-language discussions and coded reports of activity in and around sunspot groups, as well as other areas of interest on the Sun. -NC

16. How does the "South Atlantic Anomaly" affect satellites?

The South Atlantic Anomaly is a dip in the Earth's magnetic field which allows cosmic rays, and charged particles to reach lower into the atmosphere. The anomaly is always there, but it does change in intensity. The SAA is populated with high energy particles that can penetrate the skin of the spacecraft and cause upsets in spacecraft electronics.-DS

17. What types of industries might be impacted by space weather and how?

GPS sales are projected to be $9 billion per year in 2000. GPS receivers are increasingly interwoven into the fabric of commerce and recreation.

New investment in low and mid Earth orbiting spacecraft is expected to be $30 billion by 2001. Each constellation's loss of revenue is estimated at $1 k per minute of outage per satellite; this does not consider the users' losses

Delay in assembly of International Space Station could have a domino effect on Shuttle flight manifests, at $500 M per flight.

One credible electric power outage could result in a direct loss to US Gross Domestic Product of $3 - $6 billion (reference: Barnes, P.R. and J.W. Van Dyke, "On the Vulnerability of Electric Power to Geomagnetic Storms," Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1990. (published as a Technical Report of the Aoak Ridge National Laboratory)).

A recent estimate is that the use of good forecasts by the power industry could save the US $365 M per year, averaged over the solar cycle (reference: "An Estimate of the Value of Geomagnetic Storm Forecasts," by Rodney F. Weiher and Thomas J. Teisberg. (Published in an economics journal.)

18. How could I demonstrate the effect of space weather on power systems?

For demonstration of induced currents in the electrical power grid, you could find a basic induction experiment, i.e. show that a voltage, and therefore a current, is induced in a conductor when exposed to a changing magnetic flux. The basic physics configuration one sees in textbooks is a simple loop-shaped wire through which one moves a bar magnet to induce a flow of current.--CB

19. How sensitive does a meter have to be to sense voltage in an induced current?

There is a formula to calculate the current induced in the wire but it depends on the strength of the bar magnet, the rate of change of the magnetic flux threaded through the current loop, and the resistance of the circuit. The faster you can pass the bar magnet through the loop, the stronger the current. If you have a multimeter, you might test the multimeter with a simpler circuit by hooking it up a battery and a light and seeing if you can measure current flow through the multimeter.

To get a rough idea of the voltage and current produced by magnetic induction, suppose your bar magnet has a 1 Tesla magnetic field strength, and that the area of the current loop is 100 cm² (0.01 m²). When the bar magnet is in the loop the magnetic flux is the product of the field strength and the area. Let's suppose that the flux goes from zero to 1 Tesla x 100 cm² in 1 second. If we use the meter-kilometer-second system of units, then the voltage would be about

E = 1 T x 0.01 m²/1 s = 0.01 Volts

For a circuit with 2 Ohms of resistance this would give a current of 0.005 Amps, (5 mA). I have used Ohm's Law that current equals voltage divided by resistance.

As you can see, the larger the circuit and the stronger the magnetic field, the larger the current. Also the faster the field changes the larger the current. As a caution, note that I assumed a uniform magnetic field throughout the current loop. In reality the field falls off as one moves away from the magnet. The closer the magnet size is to the size of the loop, the closer the uniform field approximation works. If you can get some current readings, this experiment would be one way to estimate the field strength of a typical bar magnet.--CB

20. What satellites observe the sun that have data we can look at?

* The Solar and Heliospheric Observatory (SOHO)
* Advanced Composition Explorer (ACE) and SWPC's ACE Real-Time Solar Wind
* GOES 8 and 10
* GOES 12 -- Solar X-ray Imager
* NOAA POES - Energetic Particles
* NOAA POES - Extrapolated Auroral Activity
* Japan's YOHKOH X-ray Satellite
* Transition Region and Coronal Explorer (TRACE)
* POLAR

21. Where can I get more information?

You can find more information on the Internet at the following sites:
Space Weather Prediction Center
SWPC Education Web Page
Space Weather Sites
Space Physics Educational Sites
Solar Terrestrial Activity Report
Space Weather Report
SpaceWeather.com

 

General Space Weather | Effects on Earth | Noaa Space Weather Scales | ACE Real-Time Solar Wind