Name: TMT: The World’s Most Controversial Telescope
Uploaded: 2020-03-30T04:02:47.000Z
Duration: 12 min 46 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

The Thirty Meter Telescope, or TMT for short,

might just be the most famous—and infamous—observatory on the planet.

Which is impressive, considering it hasn't been built yet.

But what is it? Well, the TMT is just one of several ambitious telescope

projects in the works that promise to help astronomers

probe the secrets of the universe in ways that were

no more than a pipe dream a few short decades ago.

But the choice of site for this project—Maunakea,

on the Big Island of Hawai`i—has stirred up a storm of controversy.

Now, you might think, hey, you're SciShow, I know where you're going to come down on

But, look, our goal here isn't to come down on any side,

but instead to show some of the reasons why this is complicated,

and share some of the difficult questions it brings up.

Thanks to some twenty-first century improvements in technology,

the race is on to design and build the world's biggest telescope.

These projects are collectively called Extremely Large Telescopes, or ELTs.

The University of California and California Institute of Technology

were quick to begin making plans for an especially ambitious one: a thirty meter telescope.

It's called, get this The Thirty Meter Telescope, or TMT.

So the “Thirty Meter” in the name refers to the size of the observatory's aperture—

in other words, the diameter of the part of the telescope that collects light.

And that's… big. About three times as big as the biggest operational telescope of

You see, the TMT is a reflecting telescope.

It uses curved mirrors to reflect light onto a focal point, where the image is obtained.

The aperture is the diameter of the primary mirror it uses to do that—

which may be one single mirror in smaller telescopes,

or in the case of big ones like the TMT, a whole lot of little-er mirrors that work as

And bigger is better when it comes to seeing deep into the universe around us,

because the amount of light a telescope mirror can gather is proportional to the size of

Like this part isn't complicated...the more light-collecting area, the more... light is

Bigger scopes mean we might actually be able to detect the faintest of distant objects.

And that thirty-meter mirror will have nine times the light-collecting area of any telescope

but once there are, we'll be able to use them to study some of astronomy's biggest

They will have the power to peer into the so-called dark ages

of the universe...when the first heavy elements formed.

They'll reveal the large-scale structure of the universe

when it was young, including the formation of the first stars.

They'll be able to examine black holes over time

and explore exoplanets with detail and resolution we can only dream of today.

Indeed, they'll be our best shot at finding truly Earth-like, perhaps even inhabited worlds.

In other words, this is big stuff...ELTs have the potential to do amazing science.

But there are downsides to being a really big telescope, too—

like, the overall field of view becomes smaller.

And, more importantly here, bigger scopes are very sensitive to, well, everything.

You need the clearest, most ideal conditions to get good images.

You can't just stick a thirty-meter telescope anywhere.

The light from big cities would totally swamp its sensors.

the more atmosphere there is between the scope and the universe—

atmosphere that's full of turbulent air, water vapor, dust,

and other stuff which interferes with the light the telescope is trying to collect.

In some ways, the most ideal place for a telescope like the TMT is not on Earth at all.

In space, you don't have all that pesky atmosphere to deal with,

and it's super cold, as long as you can find a shadow to hide in..

like the shadow of the Earth, which is where the James Webb Space Telescope will be hiding.

But we don't have the engineering capability

to build a thirty-meter telescope in space.

The Webb will have an aperture of 8 meters. Still hefty, but not 30!

So, once they knew they wanted to build a really big telescope on Earth,

the TMT team went about deciding where would be best.

They had a list of five options at one point,

but the top two were Cerro Armazones in Chile's Atacama Desert

Either could have worked, but two others ELTs already had their eyes on Chile—

the Giant Magellan Telescope with its twenty four point five-meter mirror,

which will have a mirror that's about nine meters bigger than the TMT's.

But! Having all of the world's ELTs in the same hemisphere

would mean that we'd be missing out on studying a big hunk of the sky.

So scientists decided the TMT should be somewhere in the northern hemisphere to balance things

the TMT board announced that it wanted the telescope to be built on Maunakea.

And then the questions started popping up.

I'm not qualified to teach you native Hawai'ian tradition,

but for a necessarily imperfect metaphor,

imagine someone told a bunch of Catholics

that the best place for a telescope would be on the current site of the Sistine Chapel.

Mauna Kea is a natural temple and a sacred place of worship.

And it's not just integral to their spirituality—it's culturally important, too.

Chiefs and priests were buried high up on the mountain,

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TMT: The World’s Most Controversial Telescope

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