Last Halloween the sun let loose with a huge, hellacious (literally!) sunstorm that has sent shockwaves throughout the solar system. It was a real Halloween scare. According to one story:
On Earth, aircraft were rerouted and astronauts took cover in the international space station to avoid the effects, and the aurora borealis surged southward to the Mediterranean Sea.
The wave triggered magnetic storms on Jupiter and Saturn and peeled away parts of Mars’s upper atmosphere. Scientists suggested that such storms, spread over billions of years, could explain how Mars lost the seas that might have once covered its surface.
The significance of the event is particularly brought out by the fact that astronauts on the International Space Station hunkered down in in shielded areas (no miles of protective atmosphere with its ozone, remember?) to ride out the storm like a hurricane.
Note also that storms like this may have been what stripped Mars of its oceans. Mars may be dry because it was sun-blasted into being an endless, red beach. That’s cosmic, man!
As noted, the shockwaves from the Halloween storms were sent throughout the solar system. The problem is, the solar system is a big place. So big, in fact, that the shock waves have not yet reached the end of it.
“Where does it end?” you ask.
Well, we don’t quite know. But the shockwaves from the storm may help us figure it out. You see, the solar system is often defined as ending at a place known as . . . . Dum! Dum! Dum! . . . THE HELIOPAUSE.
“What is the heliopause?” you ask.
Here we can give a more informative answer. As you may know, interstellar space is not quite empty, despite what folks say. It contains a very, very, very x 10^something thin volume of gas and dust. Some dust, but mostly gas. And–as I said–very, very, incredibly thin. This is known among astronomers as the interstellar medium.
The interstellar medium ain’t static. It has currents that flow within it, known as interstellar winds, chiefly caused by the rotation of the galaxy. Our sun, as you know, also kicks out a wind–the solar wind–which streams out at supersonic speeds from the sun.
As it streams out, the solar wind pushes against the interstellar medium, and at some point the push against the interstellar medium is strong enough that it slows the solar wind to subsonic levels. That point is known as . . . Dum! Dum! Dum! . . . “THE TERMINATION SHOCK.” (Fooled ya, huh?)
Where the termination shock is depends on how strong the solar wind is, and that varies (with solar storms, for example). But it’s about 100 AU (Astronomical Units = the distance between the Earth and the Sun), and Voger I passed it in February 2003.
As the solar wind meets continuing resistance from the interstellar medium, even after the termination shock, it continues to slow down. When it is no longer able to resist the pressure caused by the interstellar medium, we have reached the point known as THE HELIOPAUSE. (Dum! Dum! Dum!)
The heliopause is, effectively, the boundary between our solar system and interstellar space. Thing is, it’s lopsided with respect to the sun. That’s caused by the fact that the interstellar medium is pressing against the solar systemmore strongly on one side than ‘tuther (because of galactic rotation, remember?). As a result, the sun is closer to the heliopause in the direction of rotation. Nevertheless, the heliopause is a good, logical barrier for where the solar system begins and ends. We just don’t know quite where it is.
But we may be about to find out.
Y’see, as solar winds press against it, it causes observable effects. Right now the mission of the Voyager I and Voyager II space probes is to explore this area, and the Halloween storms are likely to give them the clues they need to figure out where the heliopause is.
When the shockwave sent out by the Halloween storms smacks into the interstellar medium, it is likely to cause electrical effects (low-level radio waves) that Voyager I can detect and then tell Earth about. If so, we’ll have a good clue as to where the heliopause is (distorted as the readings may be by the strenth of the shockwave).
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Now, when Voyager 6 returns from the machine world on the other side of the galaxy, we’ll have some real data to crow about!
Jimmy,
Just so you know, I sometimes have a helluva hard time figuring out the common thread which links all your postings together.
I thought it was Vyger that went outside our solar system. I can’t wait for Vyger to come back with all the information of the universe. That’ll be cool.
Jamie,
The common thread is that I’m a curious guy. I’m interested in lots of stuff. Or, put uncharitably, I’m scatterbrained. What I’m interested in, I post about.
I do try to find a mix that other folks are interested in. At present I’m doing about 1/2 of the posts on religious subjects and 1/2 on other subjects. Don’t know if that’s the right mix or not. Feedback from folks is helpful.
Something else that is helpful is getting questions from folks. If I have religious questions to answer, I’ll tend to deal with those first. If I don’t have questions, I’ll tend to do more non-religious things just to make sure that folks aren’t disappointed by an absence of new posts when they visit the blog. I figure that an off-topic but interesting post is better than no post at all.
Brian,
Yeah, that’ll be cool, won’t it!
I know, Jimmy. In fact, that’s what I like about your blog, I was just kiddin’ around with ya. It keeps your blog from getting as emotionally draining as some other blogs out there get. Like a heavy-carb diet, they just make you feel heavy afterwards. You’re like the Atkins diet of Blogs, Jimmy.