It's Filamentary, Watson

A recent find allowed scientists some of their best views yet of the structures or filaments of gas in space that link galaxy clusters to each other over unimaginable distances.

From your basic elementary school astronomy, you probably remember that our planet is part of a solar system, organized around the star we call the sun. Galaxies are groups of thousands or millions of stars that are themselves organized around a center, which is sometimes thought to be a gigantic black hole, although no one knows for sure. Galaxies take different shapes, depending on how the stars are distributed and the effects of gravity among them. Galaxies themselves will tend to clump together to form clusters, which are made up of galaxies that are held together by the interplay of their own gravitation.

All of these systems and groups are held together by gravity. It used to be thought that the space in between galaxies -- "intergalactic" space -- was pretty much empty -- that the gravitational field produced by each galaxy was strong enough that stars or objects wandering around in it would be gradually pulled into one galaxy or another. The space in between the clusters was thought to be relatively empty as well, for mostly the same reasons.

But it isn't. There are huge filaments of gas that link the clusters to each other. And when astronomers call them "huge," that's exactly what they mean. Imagine there's a tunnel through the center of the earth with one end at the North Pole and another at the South Pole (It couldn't be done, which is why we're imagining it). Say a person at the North Pole end holds a flashlight over the tunnel and turns it on. A person at the South Pole would see the light go on just about .07 seconds later. Light from our sun takes about eight minutes to reach us. But galaxy clusters are so far apart from each other that the same action would yield a light that might take millions or even billions of years to reach us. That's how huge these gassy filaments are.

They're also apparently extremely hot. Obviously nobody's stuck a turkey thermometer into one of them to see, but the radiation they emit gives scientists some clues, and the best estimate is that they may be as much as a million degrees Celsius, or 1.8 million Fahrenheit. By comparison, the surface of our sun is a frigid wasteland, not quite nudging 10,000 Fahrenheit. To get hotter than these celestial filaments, you have to hang out in the cores of stars -- our sun's center is about 27 million degrees Fahreneheit.

Despite their size, the filaments are difficult to "see," because the radiation they give off is washed out by the immense amounts of the same radiation given off by the galaxies and galaxy clusters. So to recap -- galaxy clusters are irregular clumps that are connected by immense, superhot streams of gas that are very difficult to see clearly because of the emissions of the clusters themselves.

I believe I see a potential new synonym for "legislative body."