How a star-filled space cloud gave astronomers a new cosmic yardstick

The next time you find yourself underneath a clear, starlit sky, pretend you're an astronomer and ask yourself this: How would you accurately measure the distance between two far-away objects separated by hundreds of thousands of light years? (And no, squinting and using your fingers like little pincers doesn't count.) In our own solar system, gauging the distance between two bodies — say Mars and Mercury — isn't too much of a problem. We have tools like satellite probes and radar to help us get accurate readings. It's when we get into the far-out stretches of space, many light years away, that getting an accurate reading of distance gets tough.

To tackle this problem, scientists often use close-enough objects like the relatively nearby Large Magellanic Cloud (LMC) galaxy to estimate the distance between point A and point B — kind of like an interstellar tape measure. The problem, of course, is the universe is always expanding; it's understandably difficult to measure something when a star system keeps running away from you.

But thanks to new research from astronomer G. Pietrzyński, we might be able to get much better, more accurate readings going forward. According to Ars Technica, by identifying a "rare set of binary stars" inside the LMC, astronomers can now measure the LMC's distance from Earth down to 2.2 percent accuracy — a hair's-breadth by the universe's standards. Ars Technica's Matthew Francis explains:

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According to New Scientist, these bright star-bursts provide unique, easy-to-identify markers, which makes the LMC "a good rung on the cosmic distance ladder." By observing eight different binary systems in the star-filled cloud, the team found that the average distance between the LMC and Earth ranges from 162,900 plus or minus 3,700 light years. "This is the simplest and most accurate technique right now," says Pietrzyński.

Say hello to our new cosmic yardstick.