Tales of Brave Ulysses II – Solar Wind at Lowest Pressure Since Measurement Began
The Ulysses satellite Solar Wind Observations Over the Poles (SWOOPS) solar wind sensors are reporting a 20 percent drop in pressure, with only a 3 percent drop in speed. Dave McComas, the principle investigator for the project, states this as the lowest solar wind pressure observed since the early sixties when we began measuring it.
“What we’re seeing is a long term trend, a steady decrease in pressure that began sometime in the mid-1990s,” explains Arik Posner, NASA’s Ulysses Program Scientist in Washington DC.
How unusual is this event?
“It’s hard to say. We’ve only been monitoring solar wind since the early years of the Space Age—from the early 60s to the present,” says Posner. “Over that period of time, it’s unique. How the event stands out over centuries or millennia, however, is anybody’s guess. We don’t have data going back that far.”
What this bodes longer term is unknown, we don’t have a long history of solar wind measurements to judge by. Here’s a link to the positve Ion measurements half of the data if you want to take a look at it yourself, and I’ve also included a McComas jpg visual above, click the thumbnail to enlarge. On Earth we aren’t going to be affected short term, but Space Travel has become slightly more dangerous due to increased Cosmic Ray penetration of the Heliosphere.
“The solar wind isn’t inflating the heliosphere as much as it used to,” says McComas. “That means less shielding against cosmic rays.” Dave McComas
To picture this think of the solar wind pressure emanating from the sun as part of the atmosphere of the sun (no, it really isn’t, but bear with me a moment;) a huge bubble around the solar system called the Heliosphere. Then picture that heliosphere zooming through a dense sea of Cosmic rays. Still can’t picture it? Take a look here.
Anecdotal but truth as I know it: People living near the poles will also be exposed to more cosmic rays, which could lead to some effects. One of the visible effects I’ve observed is higher incidence of gray hair at earlier ages in populations living near the Northern pole. Earth’s magnetic shield is the backstop for the heliosphere in stopping cosmic rays from affecting life on Earth, and the shape of the magnetic field allows entry to more Cosmic rays at the poles.
Another effect could be on Clouds and climate, which the linked story speaks of.