The European Southern Observatory (ESO) — using its Very Large Telescope (VLT) in Chile and a new adaptive optics method called laser tomography — has captured remarkable images of planets, star clusters and other interstellar objects that are sharper than those from the NASA/ESA/Hubble Space Telescope.

The VLT on top of an Andes mountain. Source: ESO

The pioneering Multi-Unit Spectroscopic Explorer (MUSE) instrument using one of the two adaptive optics modes — the narrow-field mode — working with the VLT’s new system called GALACSI adaptive optics module, can now use this new technique to correct for turbulence at different altitudes in the atmosphere.

The blurring of the images taken from Earth telescopes is called “astronomical seeing.” This phenomenon is caused by turbulence in the Earth’s atmosphere, and it is a big problem for Earth-based telescopes. This is the reason that high-accuracy Earth telescopes are built in mountains, and also why space telescopes are so important.

Adaptive optics is a technology that produces sharper images by using compensating techniques to dissipate the disturbances from the atmosphere. The technique involves tracking a specific star near the object to be photographed, and watching how the light of the star surrounding it is garbled by the atmosphere. Then it adjusts the optical system to reverse the blurring effects.

However, VLT’s astronomers do not want to limit the observation of a stellar object that is located near stars whose light can be used to compensate the resulting images. The new system uses four lasers as “guide stars,” each producing an orange beam 30 cm wide. The system tracks the changes in the laser beams due to atmospheric disturbances and adjusts its mirrors to compensate. This process is performed 1,000 times per second.

The pictures that are shown here illustrate the different quality of the images obtained with the new VLT and standard tools.

Images of Neptune with and without the narrow-field adaptive optics mode of the MUSE/GALACSI instrument. Source: ESO

Neptune as viewed by the VLT adaptive optics mode and the by the Hubble Space Telescope. Source: ESO