The Giant Magellan Telescope, as it will appear at night upon completion. As humanity works together to build the newest generation of ground-based optical telescopes, with diameters between 25 and 39 meters, new facilities, technologies, and instruments need to be built to suitably equip these state-of-the-art observatories. (GIANT MAGELLAN TELESCOPE / GMTO CORPORATION)

A Giant Leap Towards Defeating Astronomy’s Greatest Enemy: Earth’s Atmosphere

Telescopes from the ground are bigger, but have to fight the atmosphere. Here’s how to win.

In astronomy, seeing farther and fainter than ever before requires three simultaneous approaches.

First light, on April 26, 2016, of the 4LGSF (4 Laser Guide Star Facility). This is presently the most advanced adaptive optics system in use aboard a modern observatory, and helps astronomers produce, in many ways, superior-quality images to what even a space-based observatory like Hubble can obtain. For the next generation of ground-based observatories, improvements and new innovations will be necessary. (ESO/F. KAMPHUES)

1.) Building bigger telescopes, gathering more light and yielding higher resolutions.

A comparison of the mirror sizes of various existing and proposed telescopes. When the Giant Magellan Telescope and the Extremely Large Telescope come online later in the 2020s, they will be the world’s largest, at 25 and 39 meters in aperture, respectively. The largest space-based telescopes, like Hubble, Herschel, and even James Webb, are all significantly smaller. (WIKIMEDIA COMMONS USER CMGLEE)

2.) Upgrading your instruments, optimizing the data from each arriving photon.

The ESO’s Very Large Telescope (VLT) contains a new imaging instrument on it, SPHERE, which allows us to image exoplanets and protoplanetary disks around smaller, lower-mass stars at high resolution than ever before, and to do so rapidly as well. Improvements in instrumentation can give older telescopes a new lease on life. (ESO / SERGE BRUNIER)

3.) Overcoming the distortive effects of Earth’s atmosphere.

This 2-panel shows observations of the Galactic Center with and without Adaptive Optics, illustrating the resolution gain. Adaptive optics corrects for the blurring effects of the Earth’s atmosphere. Using a bright star, we measure how a wavefront of light is distorted by the atmosphere and quickly adjust the shape of a deformable mirror to remove these distortions. This enables individual stars to be resolved and tracked over time, in the infrared, from the ground. (UCLA GALACTIC CENTER GROUP — W.M. KECK OBSERVATORY LASER TEAM)