This is one of the neatest visions of the Helix Nebula (a planetary nebula) that I’ve ever seen. It’s from the Spitzer Space Telescope, which looked at this remnant of a dying, Sun-like star in infrared wavelengths of light at 3.6-4.6 microns, 5.8-9 microns, and 24 microns (in blue, green, and red, respectively).
So, this image is a snapshot of various events that happened as the star’s death progressed. First, the green-blue shell is the infrared view of the first layers of gas blown off as the star began its death throes. They’ve traveled the farthest from the star. The reddish diffuse shell just inside the blue-green clouds is dust that was kicked up when the outrushing atmosphere collided with dusty comets that survived the death of the star. The comets survived the first pulse of outgassing from the star, which is a rare occurrence. As events unfolded, the cometary ices melted away, leaving behind clouds of dust to bounce around in the swirling, outrushing gas. The red ball in the center is a shell of gas that was blown away from the star as it died. And, the white dot in the center (go here to see a larger image) is what remains of the Sun-like star.
People always ask what will happen with the Sun dies. Well, it might just look like this more than 5 billion years from now!
I’m working on a project for a local museum about what happens to the upper part of our atmosphere when the Sun barfs up some plasma and sends it our way in the solar wind. The result is called “space weather.”
How does it work? Well, you start with our planet’s upper atmosphere. It’s a huge electrical circuit up there, formed by magnetic field lines and charged particles. Toss a lot of charged particles (a plasma) at it (oh, say from the Sun during a solar storm) and the result can be anything from an auroral display to a power outage.
A auroral display seen over Fairbanks, Alaska. Courtesy Jan Curtis
It all happens over our heads without us knowing much about it, unless the solar storm is fairly strong. In that case, then we usually see northern or southern auroral displays (if we live far enough north or south). If it’s a hugely strong storm, the circuits can, well, short-circuit, which can affect power grids here on the planet. Oh, and also disrupt satellite communications, fry spacecraft electronics, and pose radiation hazards to any astronauts who happen to be on orbit in the shuttle or the International Space Station.
Space weather’s a big deal, then. The exhibit I’m working on is for a children’s museum, and it’s supposed to teach them about how we learn about space weather, what the Sun’s role is, and what we do when space weather happens. It’s a fairly complex subject, and truth to tell, scientists are still nailing down the details of how our upper atmosphere (the ionosphere) reacts to varying levels of solar activity. There’s a fair amount of space weather research going on at Haystack Observatory. They’re also supplying a lot of the material for the exhibit.
An artist's view of electrons (charged particles) spiraling down Earth's magnetic field lines. They collide with neutral atoms and molecules of oxygen and nitrogen in our upper atmosphere. The collision releases energy in the form of light in different wavelengths. Image courtesy European Space Agency
Space weather is a huge area of study, and so a lot of people around the world are trying to figure out how it all works. The European Space Agency is using a set of orbiting sensors called the Cluster satellites to look at the processes that electrify our upper atmosphere. Some of their results show that the electrical circuits that form auroral displays are very complex, and that the circuits may be changing very rapidly in response to changes in plasma (the charged particles) in the area. You can read more here.
So, why should we care about these circuit changes and plasma variations and aurora thingies going on over our heads? Space weather, as I mentioned above, affects power systems here on the planet. It can sizzle electronics on orbiting spacecraft. But, it can hit you where you work and live, too. Think about that GPS unit in your car. Or the cell phone you can’t live without. Or the Blackberry. They all depend on communication between orbiting spacecraft and receiving stations here on the planet. Your radio does, too. So does your TV. Many kinds of long-distance communications depend on the ionosphere for “signal bounces” from place place. Disrupt the ionosphere and you disrupt the signals for all these technologies.
Understanding space weather is supposed to help us harden our technologies, or at least turn them off in the event of a big storm. It’s all part of understanding our planet and what can happen to it.
