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Heliophysics Fun Facts
July 26, 2011

Heliophysics -- the study of the Sun-Earth connection -- is still a relatively young scientific field of study and is not something you hear mentioned every day, though the term "Space Weather" has made inroads with our culture.
NASA's study of Heliophysics is divided into five overlapping disciplines, or areas of study;

Click on any of the above links to view facts regarding each Heliophysics discipline. These Fun Facts were compiled from what we have already learned in the field of Heliophysics. Try some of these Fun Facts at your next gathering and impress your friends with your knowledge of Heliophysics.

The Heliosphere
  • [image-69]The solar wind plasma near the Earth is only about 6 particles per cubic centimeter.
  • The Heliosphere is the entire region of space influenced by the Sun.
  • The boundary where the solar wind's strength is no longer great enough to push back the interstellar medium (ISM) is known as the heliopause.
  • The solar wind magnetic field is twisted into a spiral by the Sun's rotation.
  • The solar wind consists mostly of protons and electrons, but it also consists of ions of almost every element in the periodic table.
  • The solar wind emanates from the Sun in all directions.
  • Hydrogen and helium make up about 99.9 percent of the solar wind.
  • The particles of the solar wind, and the Sun's magnetic field are stuck together, therefore the solar wind carries the IMF (interplanetary magnetic field) with it into space.
  • The solar wind particles travel at supersonic speeds of 200-800 km/sec.
  • The termination shock is where the solar winds slow down to speeds slower than the speed of sound (subsonic).
  • The region between the termination shock and the heliopause is called the heliosheath.
  • The subsonic solar wind flow is turned in the "heliosheath" between the termination shock and the heliopause to flow down the "heliotail."
  • Electricity and magnetism are closely related. Charged particles can participate in an electric current and create a magnetic field.
  • The slow solar wind has a velocity of about 400 km/s and originates from a region around the Sun's equatorial belt that is known as the "streamer belt".
  • The slow solar wind is twice as dense and more variable in intensity than the fast solar wind.
  • The fast solar wind has a typical velocity of 750 km/s and is thought to originate from coronal holes, which are funnel-like regions of open field lines in the Sun's magnetic field, most prevalent around the magnetic poles.
  • One million tons of particles come from the Sun every second.
  • The Heliosphere is tiny as compared to the distance to the nearest star. It measures across a bit more than a light day as compared to greater than four light years to Alpha Centauri.

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The Sun
  • [image-87]The unique sound produced by a priceless Stradivarius violin can be traced back to the effects of sunspots.
  • Our Sun has lots of company: it is one of more than 200 billion stars in the Milky Way Galaxy alone. Every individual star that you can see with the naked eye is in the Milky Way.
  • Stars are factories for new elements. As they live and die, they convert their hydrogen gas into all the rest of the elements on the periodic table. These elements make up Earth and you.
  • A star’s mass—how much matter it contains— determines its temperature, luminosity, color, and how it will live and die.
  • Our Sun is more massive than the average star in its neighborhood. Nearly 90% of stars are less massive, making them cooler and dimmer.
  • The hottest and most massive stars are bright and blue, while the coolest and least massive stars are dim and red. Yellow stars, like our Sun, are in-between.
  • About 99% of stars, including our Sun, will end their lives as white dwarfs. Only about 1% of stars are massive enough to explode as a supernova.
  • It takes light 200,000 years to escape from the Sun but only 8 minutes to reach the Earth.
  • The iron in your blood was made in the cores of stars that exploded billions of years ago.
  • The Sun contains 99.9% of all matter in our solar system.
  • During a single second, the sun converts 4 million tons of matter into pure energy.
  • The Sun's radius is 432,470 miles, which is equal to 109 Earth radii.
  • It would take about 1 million Earths to fill the Sun if it were a hollow ball.
  • The August 4, 1972 solar flare was so powerful that, by some estimates, a space-suited astronaut would have received a lethal dose of radiation.
  • The Sun rotates on its axis approximately once every 27 days.
  • The Sun's surface rotates at different speeds in different locations. The fastest rotation is at the equator (approx. 25.4 days). The slowest rotation is at the poles (approx. 36 days).
  • The Sun is 93 million miles away from Earth and is almost 5 billion years old.
  • On April 8, 1947, the largest sunspot in modern history reached its maximum size of over 35 times Earth's area.
  • Solar flares can sometimes heat the solar surface to temperatures of 80 million F - far hotter than the sun's core.
  • The core of the Sun is nearly as dense as lead, and has a temperature of 15 Million degrees Celsius. The coolest part of the Sun is nearly 6,000 degrees Celsius.
  • The primary energy the Earth receives from the Sun is radiant energy, or light.

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The Magnetosphere
  • [image-105]The Earth has its very own protective shield called the magnetosphere.
  • Earth's magnetic field is off-set from its rotational axis by 11.4°
  • The Earth's magnetic field reaches 36,000 miles into space.
  • The Earth's north and south magnetic poles reverse at irregular intervals of hundreds of thousands of years.
  • A magnetosphere has many parts, such as the bow shock, magnetosheath, magnetotail, plasmasheet, cusps, plasmasphere, radiation belts and many electric currents. It is composed of charged particles and magnetic flux.
  • The magnetotail is the main source of the polar aurora.
  • The most powerful aurora can generate over 1 trillion watts of power.
  • Electric currents high above the surface can cause ground induced currents that disrupt power transmission and degrade pipelines.
  • A "magnetic substorm" is a violent discharge of magnetic energy, accumulated in the magnetotail, observable in Earths auroral zones.
  • Aurora like the ones on Earth can be seen on Mercury, Jupiter, Saturn, Uranus, and even Neptune.
  • In a period of one second, the outer limit of the magnetosphere, the magnetopause, is hit with the same amount of energy that is produced by all Swedish power plants in three years.
  • A Coronal Mass Ejection (CME) shock waves compress the Earth's magnetosphere like it is a balloon.
  • A "magnetic storm" is a disturbance of the magnetic field observable all around the globe, lasting a few days and adding to Earth's trapped plasma.
  • The Van Allen Belts were the first thing discovered by a man-made satellite.
  • The March 13, 1989 Quebec blackout, the result of a major geomagnetic storm, caused a $6 billion loss to the Canadian economy.

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Near-Earth Space
  • [image-123]The layers of the atmosphere are not always the same height all around the Earth and they expand and contract with temperature fluctuations throughout the year.
  • The ionosphere allows you to talk around the world using only a few bounces of a radio wave.
  • The ionosphere makes long distance radio communication possible by reflecting radio waves back to Earth.
  • Auroras form in the ionosphere between 60 and 250 miles above Earth's surface.
  • The plasmasphere is considered an extension of the ionosphere.
  • The troposphere, the lower atmosphere, contains 99% of the atmosphere's water vapor.
  • The troposphere and stratosphere contain 99.9% of the total mass of the atmosphere.
  • The mesosphere and stratosphere are referred to as the middle atmosphere.
  • The ionosphere and magnetosphere are closely linked via magnetic field lines and heat can be conducted from the magnetosphere down to the ionosphere.
  • All atmospheric layers exchange gas and energy all the way out to the magnetosphere.
  • During a severe solar storm, Earth loses about 100 tons of atmosphere into space.
  • Earth spews an average of 50 tons of plasma (ions) per day at speeds up to 100,000 kilometers per hour from the North and South pole regions.
  • Sudden Ionospheric Disturbances (SID) are caused by solar flares and coronal mass ejections (CME) and result in a change in density and location of the ionosphere layers.
  • Space weather's affect on the ionosphere can distort radio signals and navigation devices. In March 1989, listeners in Minnesota could hear the broadcasts of the California Highway Patrol.
  • Only half of Earth's ionosphere is being ionized by the Sun at any time. At night, ionization comes from cosmic rays from activity in the magnetosphere and from sources throughout the galaxy.

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Space Weather
  • [image-141]Solar Wind is plasma moving away from the Sun at a million miles an hour.
  • Studying how the Sun's variability affects the Earth requires identifying the sources and timescales of the solar variability and measuring the response.
  • The travel time for the solar wind from the Sun to the Earth is two to four days.
  • The largest, single, challenge for astronauts traveling to Mars will be to overcome exposure to solar storms and radiation.
  • Space weather is caused by charged particles and their motions.
  • Space Weather Forecasting costs a few million dollars a year, but supports hundreds of billions of dollars in annual revenue from the satellite and electrical power industries.
  • Between May 10-12, 1999, the solar wind nearly vanished.
  • The temperature of solar wind plasma around the Earth is about 150,000 Kelvin.
  • The change of the ionization of our upper atmosphere by Space Weather affects radio communications and GPS navigation.
  • During space weather disturbances, small magnetic field changes in near-Earth space produce changing magnetic fields and electric currents that are felt at the Earth's surface.
  • Homing pigeons have been observed to become confused during space weather disturbances and can even be lost.
  • An average solar flare or CME releases, in two hours, enough energy to power the United States for 10,000 years.
  • A major solar superstorm such as the Carrington Event in 1859 could cost $30 billion a day to the US electrical power grid, and up to $70 billion to the satellite industry.

Holly Zell / Jennifer Rumburg
NASA's Goddard Space Flight Center, Greenbelt, Md.

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Artist concept of Heliosphere with labels.
This is an artist's concept of our Heliosphere as it travels through our galaxy with its major features labeled.
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Labeled internal and external features of the Sun.
The sun and its atmosphere consist of several zones or layers. From the inside out, the solar interior consists of the core, the radiative zone, and the convection zone. The solar atmosphere is made up of the photosphere, the chromosphere, a transition region, and the corona.
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Artist concept of Earth's Magnetosphere with its parts labeled.
A magnetosphere is that area of space, around a planet, that is controlled by the planet's magnetic field. The shape of the Earth's magnetosphere is the direct result of being blasted by solar wind, compressed on its sunward side and elongated on the night-side, the magnetotail.
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Diagram of the layers within Earth's atmosphere; the Troposphere, the Stratosphere, the Thermosphere, the Ionosphere, and the Exosphere.
This diagram shows the layers within Earth's atmosphere; the Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, the Ionosphere, and the Exosphere
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Artist concept of space weather and earth-based technology affected by it.
Space weather refers to conditions on the Sun and in the space environment that can influence the performance and reliability of space-borne and ground-based technological systems.
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Page Last Updated: November 26th, 2014
Page Editor: Holly Zell