Tales of Brave Ulysses II – Solar Wind at Lowest Pressure Since Measurement Began

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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.

Tales of Brave Ulysses: Solar Winds Ebb to Fifty Year Low

The solar winds are now the lowest they’ve been in fifty years, meaning that the Sun’s effects on our solar system are also at an ebb. The Ulysses solar probe is providing these measurements, and the winds have not only lessened, but are also 13% cooler. Much more at BBC.

“This is a whole Sun phenomenon,” said Dave McComas, Ulysses solar wind instrument principal investigator, from Southwest Research Institute, San Antonio, US.

“The entire Sun is blowing significantly less hard – about 20-25% less hard – than it was during the last solar minimum 10-15 years ago.

“That’s a very significant change. In fact, the solar wind we’re seeing now is blowing the least hard we’ve see it for a prolonged time, since the start of those observations in the 1960s at the start of the space age.”

In addition to being calmer, the wind measured at Ulysses is 13% cooler.

However, judging from Sun activity data collected by non-satellite methods over the past 200 years, the current behaviour is thought to be well within the long-term norm.

Nonetheless, scientists expect the weakened wind to have a wide range of impacts.

Among the notable effects of this will be cooling of our upper atmosphere, and increased penetration through the solar system of external cosmic rays.