This is a cropped portion of a data plot showing the solar wind speed and density from December 1999 - December 2000. Please click on image for full view. In that full view, you can see that wind speeds remain between 200-800 km/s. It's possible, but rare, for solar wind to reach speeds above 800 km/s. All data was collected by the SWOOPS instrument
Click on image for full size
NASA, ESA and LANL (the principal investigator of SWOOPS)
Characteristics of the Solar Wind
The sun is flinging 1 million tons of matter out into space every second! We call this material solar wind.
But just what makes up the solar wind, how dense is it, how fast does it travel and just how hot is it?
The solar wind is made of Hydrogen (95%) and Helium (4%) and Carbon, Nitrogen, Oxygen, Neon, Magnesium, Silicon and Iron (~1%). These atoms are all in the form of positive ions which means they have lost electrons because the temperature is so hot. So really, solar wind is positive ions and the electrons these ions have lost. We call this plasma.
At the orbit of the Earth, the solar wind has an average density of about 6 ions/cm3. This is not very dense at all! Take a look at this picture for comparison with Earth's atmosphere. So even though the solar wind moves incredibly fast (normally in the range from 300 to 600 km/s), it wouldn't even ruffle your hair if you were to stand directly in the midst of a solar wind breeze! But, some explosive events like solar flares or CME's on the Sun can produce speeds over 1000 km/s!
The solar wind goes all the way past Pluto. Scientists hope the Voyager spacecraft will reach the end of the solar wind, the heliopause. Scientists sure are interested to see what the solar wind is like that far out!
The temperature of solar wind plasma around the Earth is about 150,000°K.
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