Our Milky Way galaxy is a vast collection of stars, gas, and dust, spread out into flat disk with embedded spiral arms and a central hub of stars like a squashed ball. You wouldn’t think that a structure half the size of the galaxy itself could hide from us, but that’s exactly what we found out:
Two vast bubbles of gas are being blown out of the galaxy’s center, and they’reeach 50,000 light years long! The picture above shows them (in blue) superposed on an all-sky image of the Milky Way; if you could see in radio light they’d stretch halfway across the sky.
We’ve seen hints of these gigantic fountains before, but the Parkes radio telescope in Australia provided astronomers with key information about them, including their cause: huge episodes of star birth, which pump tremendous amounts of energy into the galaxy. How much energy? The equivalent of a million stars exploding. That kind of power is staggering, and happily is going on at a distance of 250 quadrillion kilometers away; far enough that they can’t affect us physically. But we can still see them, study them, and marvel at them.
Credit: Photo by Ettore Carretti, CSIRO (radio image); S-PASS survey team (radio data); Axel Mellinger, Central Michigan University (optical image); Eli Bressert, CSIRO (composition)