How Stellar Blur Gives Away Dark Energy express
Light from a distant star, after passing through air and telescope lenses, loses its sharpness, like looking at a streetlamp through wet glass. Astronomers call this blur the telescope's "fingerprint": each instrument has its own, and you need to know it down to the smallest detail.
Previously, this "fingerprint" was captured piecemeal: each light-sensitive chip of the camera was processed separately, and the overall picture lost coherence. Now, a neural network learns from thousands of star images from the Subaru Telescope and reconstructs the blur across the entire field of view, like a restorer piecing together a fresco from surviving fragments.
This matters for the big picture: from barely perceptible distortions in the shapes of distant galaxies, scientists calculate how fast the universe is expanding. The more precise the blur measurement, the fewer errors in those calculations. The new method is being prepared for a future sky survey that will capture millions of stars every night.
Earth's atmosphere blurs starlight just as water blurs pebbles at the bottom of a stream: the deeper you look, the more the image shimmers.
In the series "The Expanse," astronauts adjust telescope images on the fly — without an accurate blur model, their maps of distant worlds would be useless.