One of the most significant hurdles for astronomers using telescopes on Earth is our atmosphere. It’s why many of the breathtaking images we see come from telescopes orbiting high above the Earth’s surface.
You can see this hurdle anytime you look up in the night’s sky. See all those twinkling stars? That’s caused from the turbulence in Earth’s atmosphere. Astronomers can’t get rid of the turbulence, but they can offset its effect using a technology called adaptive optics.
The European Southern Observatory’s Very Large Telescope (VLT) recently captured its first image (dubbed “first light”) with a new adaptive optics mode called laser tomography. Here’s a fantastic snapshot of Neptune.
The VLT’s MUSE (Multi Unit Spectroscopic) instrument gets a major assist from the adaptive optics unit called GALACSI. In Narrow-Field Mode, the VLT can now capture visible wavelength images that are sharper than NASA’s Hubble Space Telescope.
Here’s a side-by-side showing Neptune as seen by VLT now versus the Hubble Space Telescope.
Neptune is cool and all, but Hubble flexes its muscle with deep space imagery. A fresh look at the globular star cluster NGC 6388 shows the huge improvements adaptive optics offer.
How VLT’s adaptive optics work?
A combination of lasers and a deformable mirror make it all happen.
Four columns of bright orange light are shot into the sky, “stimulating sodium atoms high in the atmosphere and creating artificial Laser Guide Stars,” according to the ESO. The GALASCI then uses the light from these artificial stars to figure out the amount of turbulence in the atmosphere and sends the corrections (one thousand times per second) to a deformable secondary mirror that continuously changes shape to correct it.
The before and after results are stunning.
While many of us are eagerly awaiting the launch of the James Webb Space Telescope, new technology like adaptive optics show telescopes back on Earth can deliver image quality exceeding some of the best telescopes in orbit today.