Why we need TMT
I take issue with the recent letter of Tomas Belsky and Moanike‘ala Akaka regarding their comments on the scientific importance of the Thirty Meter Telescope. I am an astronomer, who during the past five decades has observed at most of the telescopes on Maunakea, as well as at telescopes elsewhere.
Mr. Belsky and Ms. Akaka are correct in stating that the Event Horizon Telescope, actually a group of telescopes stretching around the globe, was able to image a supermassive black hole in a distant galaxy without the TMT. But they are incorrect in suggesting that this shows the TMT is not needed and that existing telescopes will suffice.
The TMT will operate at optical (visible) and infrared wavelengths. The Event Horizon Telescopes — including two on Maunakea that by working together imaged the black hole — are radio telescopes. No optical/infrared telescope would be able to make that observation.
On the other hand, no radio telescope or array of radio telescopes can observe most types of stars, planets orbiting stars, brown dwarfs, most of the objects in our solar system, individual stars in other galaxies, the fascinating details of stellar evolution, the formation and evolution of galaxies after the Big Bang, supernovae … the list goes on and on.
Telescopes come in many flavors: optical, infrared, radio, ultraviolet, X-ray, gamma ray, gravitational wave, neutrino. None of these types of telescopes can see everything in our amazing universe. It takes many types of telescopes for us to even begin to reach an understanding of what is out there, whether life exists on extrasolar planets, how our present universe came to be and what it will be like in the future.
The TMT, an optical and infrared telescope planned to be located just below the summit of Maunakea, arguably the best site on Earth for optical and infrared astronomy, will be by far the largest such telescope in the northern hemisphere.
Because Hawaii is close to the equator, it will have access to a large fraction of the sky. It will enable groundbreaking discoveries and advances in our understanding of the universe that no other telescope will be able to make.