There's a new star in the sky -- and it was put there by astronomers using a giant laser. Installed on to one of the telescopes at the European Southern Observatory's (ESO) Paranal site in Chile this February, the laser projects a "star" on to the sky, which helps astronomers, get a clearer view.
"We project a beam with a diameter of about 50cm, and make a 'star' about 90km up in the atmosphere," explains ESO laser engineer Steffen Lewis. This artificial star acts as a reference point for atmospheric distortion. The light waves it sends back to Earth are "crinkled" by the turbulence and changing density of the atmosphere; this is why stars seem to twinkle. A sensor in the telescope measures the distortion, and very thin deform-able mirrors are automatically reshaped to compensate.
· Since the laser was installed, astronomers have observed distant objects such as the dwarf planet Haumea and radio galaxy Centaurus A. "By seeing more clearly into the atmosphere, you get very sharp images," explains Lewis.
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