The solar wind is a gas plasma blown off the surface of our sun at a million miles per hour. It is the outer atmosphere of the sun expanding out into space in all directions all the time. It effectively forms a shield around our solar system like a bubble that is called the heliosphere that tends to reflect harmful cosmic rays originating from other star systems, basically pushing away the rest of the galaxy from our solar system. This outward flow of particles is constant and creates outbound pressure referred to as a wind, a solar wind.

Sometimes it is stronger than at other times. Apparently, it is also sometimes weaker, as new data suggest.

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An image of the sun taken Sept 25 using the SOHO observatory’s Extreme ultraviolet Imaging Telescope at 304 Angstrom. SOHO, NASA/ESA

This is perplexing. The strength of the wind forms a pressure barrier that repels the intergalactic cosmic radiation, which is quite harmful to life, especially life floating around in space, space stations and spacecraft. Earth is protected by its magnetosphere and by its atmosphere for two additional tiers of protection. Spacecraft orbiting the Earth would also be protected by its magnetosphere. Spacecraft en route to the moon would have minimal protection.

The spacecraft Ulysses launched in October 1990, is a mission out of the plane of the planets orbiting the polar regions of the sun. Ulysses has detected a gradual decrease in the solar wind over the last 15 years equal to nearly 25%.

A segment today on Science Friday, talks to David McComas, Principal Investigator for Solar Wind Observations over the Poles of the Sun (SWOOPS) Experiment, about the solar wind and the findings by the spacecraft Ulysses. The archived podcast should be available later today here.

The Ulyssess/SWOOPS web site is here: http://swoops.lanl.gov/ .

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I have always liked the idea of symmetry; makes for a pleasing appearance and is well ordered. Apparently this is not true for our solar system, which appears to have the middle aged ‘dunlap’ disease. Our solar system’s gut has done lapped over its belt.

This information is coming in to researchers courtesy of the 1977 vintage Voyager 1 spacecraft, which is now reaching a distance of 9.9 billion miles from Earth and is entering the Sun’s heliosheath; a region of space where the solar system’s reach ends and the area of interstellar space begins. Other bodies in the galaxy begin to exert more influence on objects in this region than does our sun.

The thin layer of interstellar gas pushes back the solar wind and its magnetic effects that emanate from the Sun, creating a magnetic bubble, a gut if you will, and the Voyager data seems to be saying that this “gut” is not round. The solar system may in fact be rather oblong, similar to the effect of pushing a round balloon against a wall where it would be blunted on one side.

Both Voyager 1 & 2 are powered by long-lived nuclear fueled batteries, enabling them to continue to operate in the absence of solar energy for these past thirty years. It is estimated they will have sufficient power to operate their radio transmitters until after 2025, 48 years after launch, at which time it will be a matter of pure luck if they still work.

 

Voyager 1 is in the heliosheath.

From left to right in the image above: interstellar gas, the bow shock, the heliopause, Voyager 1 and Voyager 2, the heliosheath, the termination shock and the heliosphere.