How much do you know about Space Weather? Try your hand at
some of the questions below. Click on the question to see the answer. The
Glossary and Science Briefs
have more information to help you out.
Q. How many Earths can fit into the Sun?
A. About 1,000,000.
Q. How long does it take energy produced in the Sun's core to make its way to the surface?
A. About 150,000 years. The nuclear fusion process in the Sun's core produces, among other things, gamma rays. These gamma rays are constantly absorbed and re-emitted as they move through the sun, essentially bouncing in random directions. By the time this "random walk" takes them to the Sun's surface they have been transformed into visible light. This light escapes from the photosphere and arrives at Earth about 8 minutes later.
Q. High energy particles from the Sun are a serious hazard to astronauts. What protects passengers on the Space Shuttle from deadly solar radiation?
A. Earth's magnetic field deflects most (98%) of the energetic particles from the Sun. So long as astronauts are within Earth's magnetosphere, they are relatively safe (except during magnetic storms). Astronauts on the moon or traveling to Mars are in far greater danger.
Q. Who was the first person in modern history to observe sunspots?
A. Galileo was the first person in modern history to observe and study sunspots.
Q. What terrestrial visual phenomenon is associated with magnetic storms?
A. Aurora are more intense and more widespread during magnetic storms.
Q. What is the name given to the constant outward stream of particles from the Sun?
A. The solar wind is a gas of charged particles that blows outward from the Sun at a million miles per hour.
Q. What was the Maunder Minimum?
A. The Maunder Minimum was the period 1645 to 1710 when very few sunspots were seen.
It has been proposed that the decreased solar activity was responsible for unusually
cold conditions during that period.
Q. What is the average temperature of the solar photosphere?
A. The mean solar photospheric temperature is around 10,832 degrees Fahrenheit (6000 degrees Celsius.)
Q. A sunspot has two distinct areas. What are their names?
A. The dark center of a sunspot is the umbra, the lighter area surrounding the umbra is the penumbra.
Q. Name three effects of a magnetic storm.
A. A magnetic storm affects HF communication, astronauts working in space, and aurora.
Q. In what months are magnetic disturbances on Earth most probable?
A. Magnetic disturbances are more probable around the equinox months.
Q. What is the average geomagnetic field strength?
A. The average geomagnetic field is roughly one gauss, or 10-4 Tesla (less than the magnetic field of a refrigerator magnet.) The average magnetic field on the Sun's surface is also around one gauss, but the field
strength in sunspots can be 1000 times that.
Q. For what does the acronym SSC stand?
A. An SSC is a Sudden (geomagnetic) Storm Commencement.
Q. What is the average length of a sunspot cycle?
A. The average length of a sunspot cycle is 11 years.
Q. What is the approximate delay between a coronal mass ejection and a geomagnetic storm on Earth?
A. A magnetic storm may occur 2 to 4 days after a large solar flare or coronal mass ejection.
Q. What is the approximate solar rotation period at sunspot latitudes?
A. At sunspot latitudes, the Sun appears to rotate about once every 27 or 28 days.
Q. What solar phenomenon is believed associated with recurrent magnetic storms?
A. Coronal holes are believed associated with recurrent magnetic storms.
Q. What frequency of solar radio emission correlates best with overall solar activity?
A. Solar radio emission at 3000 MHz gives a good overall indicator of solar activity.
Q. What is a possible geoeffect of a coronal mass ejection?
A. A coronal mass ejection may be followed by a geomagnetic storm
Q. What phenomenon is shown in the sunspot "Butterfly diagram" ?
A. The "Butterfly Diagram" shows the migration of sunspot group appearances from middle to low latitudes throughout the course of the sunspot cycle.
Q. Only two techniques can currently probe the solar interior. Name them.
A. Core neutrino emission and helioseismology are two probes of the Sun's interior.
Q. How powerful is a magnetic storm?
A. A large magnetic storm generates about 5 tera watts of power ( 5 x 1012 watts). This is about the same power capacity of the United States.
Q. How powerful is a solar flare?
A. A solar flare that lasts several hours is so powerful that it could provide the energy needs of the United States for about 10,000 years.