Everything Everywhere Daily: History, Science, Geography & More - Really Big Telescopes

Episode Date: November 10, 2020

Since the dawn of time, humans have looked up at the night sky to watch the stars. ...and then nothing happened for hundreds of thousands of years until a guy by the name of Galileo Galilei point a telescope at the stars and saw a bunch of stuff that everyone had missed. Since then, we’ve increased the size of our telescopes so we can see more and more, further and further away. Learn more about the ever-increasing size of astronomical telescopes on this episode of Everything Everywhere Daily. Learn more about your ad choices. Visit megaphone.fm/adchoices

Since the dawn of time, humans have looked up at the night sky to watch the stars. And then nothing happened for hundreds of thousands of years until a guy by the name of Galileo Galilee pointed a telescope at the stars and saw a bunch of stuff that everyone had missed. Since then, we've been increasing the size of our telescopes so we can see more and more further and further away. Learn more about the ever-increasing size of astronomical telescopes on this episode of Everything Everywhere Daily. Fear is the virus is trending on TikTok. scenes are poison. Then your yoga teacher says that sex traffic children are being sacrificed by satanic liberals, but it's all okay. The Great Awakening is coming. What is happening? Every week on Conspirality Podcast, we explore the fever dreams that suck friends, family, and wellness

gurus down the right-wing cult spiral in a search for salvation. This episode is sponsored by audible.com. My audiobook recommendation for today is Astrophysics for people in a hurry written and narrated by Neil deGrasse Tyson. What is the nature of space and time? How do we fit in the universe? How does the universe fit within us? There's no better guide through these mind-expanding questions than a claimed astrophysicist and best-selling author Neil deGrasse Tyson. But today, few of us have time to contemplate the cosmos. So Tyson brings the universe down to Earth succinctly and clearly with sparkling wit and digestible chapters, consumable anytime, and anywhere in your busy day.

You can get a free one-month trial to Ottawa. and two free audiobooks by going to audibletrial.com slash everything everywhere or by clicking on the link in the show notes. On January 7th, 1610, Galileo picked up a telescope and pointed it at the planet Jupiter. It marked a major turning point in human history. This was the moment when astronomy was separated from astrology. Prior to this moment, humans were more concerned with grouping together specks of light and following their path in the sky than they were with trying to figure out what those specks of light were. In fact, most people never really bothered to think that those specks of light might be anything other than specs of light.

The telescope, which was used by Galileo, was nothing more than what you might find in a toy store, with a magnification on a par with a decent pair of binoculars. With this very simple tool, he was able to immediately discover things that we all take for granted, but were never known to humanity beforehand. He discovered that Jupiter had moons, that Venus had phoises, that the moon had mountains, that the Milky Way was made up of stars, that Saturn had rings, and that the sun had sunspots, and that it rotated. Once these discoveries were made public, the race was on to create larger and more powerful telescopes.

And here I should explain the basic principle of telescopes. The power of a telescope is based on the aperture or the diameter of the lens. The larger the lens, the more light can be gathered. If you think of photons of light as drops of water streaming down, and a telescope is a bucket, then the bigger the bucket, the more photons you'll be able to capture. A telescope with a glass lens you look through is called a refracting telescope. As a lens gets larger and wider, the area of the lens will grow in size corresponding to the square of the radius. Galileo's first astronomical telescope had an aperture of 1.5 centimeters.

Within 10 years, the aperture of his telescopes had almost tripled in size to 3.8 centimeters. By the end of the 17th century, Dutch astronomer Christopher Hoygens was using a telescope with an aperture of 22 centimeters. With this, he was able to see Saturn's largest moon Titan. There was a big problem with these telescopes, however. As they got larger, it became more and more difficult and more and more expensive to create the lenses. Glass is heavy. As lenses get larger, they require longer focal lengths, which means larger tubes. Eventually, astronomers had to create small buildings to house their telescopes.

They also needed very heavy mounts to hold such large and heavy objects in place. Finally, crafting and grinding such large lenses at this scale was just really hard to do. Refracting telescopes did increase in size throughout the 19th century, but eventually they hit a limit. The largest refracting astronomical telescope ever made was built in 1897 at the Yerxes Observatory in Wisconsin. It has an aperture of 104 centimeters or 40 inches. Today, it's a museum piece. There was a larger refracting telescope made for the 1900 Great Paris Exhibition. It had an aperture of 125 centimeters.

However, it was designed more as a novelty and not as a scientific device. It was pointed horizontally through what looked like an oil pipeline, and it had a focal length of 57 meters or 187 feet. It was taken down after the exhibition. Beyond this one-meter threshold, refracting telescopes are simply too impractical and expensive to build. Thankfully, a guy you might have heard of called Isaac Newton invented another type of telescope back in 1668 called a reflecting telescope. Instead of a glass lens you looked through, it used a large curved mirror at the bottom of the tube. Light would go into the tube, hit the mirror, and would get focused to another mirror back near the opening of the tube, which would bounce the light sideways to an eyepiece.

The reflecting telescope had a huge advantage over the refracting telescope in that a mirror was far easier, cheap, and lighter to manufacture than a glass lens. By the 18th century, the largest telescopes were all reflecting telescopes, and that was where most of the major astronomical research was being done. In 1785, English astronomer William Herschel was using a reflecting telescope with a 120-centimeter mirror, and with this, he was able to discover the planet Uranus, as well as Saturn's sixth and seventh moons. The entire apparatus to hold up the telescope was enormous and looked like an oil rig. The mirrors kept getting bigger. The Hale telescope at the Mount Wilson Observatory in California was a meter and a half in diameter in 1908, and the Hooker telescope, also at Mount Wilson,

was a two and a half meter telescope installed in 1917. Going back to my analogy of a telescope as a light bucket, the size of the bucket is the biggest factor in how much light you will collect. Another factor was how long you let the bucket fill up with light. The longer you hold a bucket under running water, the more water you will collect. and the same is true with light. Up until the late 19th century, all telescopes worked by an astronomer putting their eye on an eyepiece

and looking at the light as it streamed through the telescope in real time. A major development was the use of cameras. A camera, assuming that the telescope could move with the rotation of the Earth to keep it still, could collect light for a much longer period of time. What might look like a blurry smudge to the naked eye can be a crisp, sharp, bright image

from a camera with a long exposure. Astrophotography became the way in which all serious astronomy was conducted. One of the first major achievements of astrophotography was the discovery of Pluto. It's believed that astronomers actually did see Pluto before it was known to be a planet. However, it was so far away and so slow that nobody knew it was moving. Pluto's discoverer Clyde Tombaugh discovered the object by comparing photographs and notice that one of the tiny lights moved. Today, all professional astronomical telescopes are reflecting telescopes with a camera. In fact, the really big telescopes don't even have eye pieces.

Just as large glass lenses had a limit in size, so too did large mirrors. As mirrors became bigger, they became subject to gravity distorting the mirror. The surface of the mirrors had to be ground down to an insanely smooth level of well less than a micron. By the 1980s, the big single mirror had run its course. They needed new techniques to make larger telescopes. One such technique was adaptive optics. as light comes through the atmosphere can get blurred. This is why stars appear to twinkle.

Adaptive optics can make thousands of tiny micro-adjustments to the mirror in real time to compensate for the changes in the light. Segmented mirrors also allowed for larger telescopes. Rather than make one massive mirror, you can make many smaller hexagonal mirrors that fit together to make one big mirror. Finally, you can make multiple telescopes work together through what's known as interferometry. In 1993, the Kek 1 and Kek2 telescope, were opened. At the time, they were individually the largest telescopes in the world,

with each telescope having mirrors with a diameter of 10 meters. The Kek telescopes used all of the above techniques I mentioned. The main mirrors are segmented, use adaptive optics, and they can be used together via interferometry as one giant 85 meter telescope. Since the KECs were opened almost 30 years ago, the crown of the largest telescope was taken by the Grand Telescope of Kinerias in the Canary Islands, which has a 10.4 meter mirror. I've been able to see both the Keck and the Grand Telescopo up close on tours, and it's well worth the time and effort to see them if you are ever in the area. These, however, are not the last big telescopes.

Progress in the creation of giant mirrors hasn't stopped. Currently, the European extremely large telescope, or ELT, is under construction in Chile. It will have a 39.3 meter diameter primary mirror, which is almost four times the diameter of the current largest telescopes. The ELT is expected to help in the search-defined Earth-light planets around other stars. It is expected to see first light in 2025. There are even conceptual plans for something called the OWL, or the overwhelmingly large telescope. This would have a 100-meter mirror.

This is still in the planning stages, and building a telescope of this size would be an enormous undertaking. However, from an engineering perspective, at least, it is feasible. All of the biggest telescopes, both present and future, are all found in only a few places on Earth. They're in the Atacama Desert in Chile, on top of Monacaea in Hawaii, or on the island of La Palma in the Canary Islands. The reason for this is weather. When you build something this big, you want to have as many viewing days as possible. Cloud cover prevents you from seeing anything, so you need a location that's either above the clouds, like on Monacaea, or in a place that has no clouds, like in the Atacama.

While something like the OWL might be possible, even the large reflecting telescopes are running into problems. Not only do massive telescopes cause billions of dollars, but there are cultural issues with building new telescopes in places like Monacaea, and we are ultimately limited to the fact that we're on Earth with all of our messy atmosphere and a sun which ruins observations for half of each day. All of these problems can be solved by going to space. In 1990, the Hubble Space Telescope was launched on the space shuttle. With a 2.4 meter mirror, it isn't close to being the largest telescope on Earth. However, it has several advantages over ground-based telescopes. Because it's in the vacuum of space, the atmosphere is a non-issue.

Also, it can take very long exposures. The Hubble Extreme Deep Field image was a single image taken over the equivalent of a 23-day or 2 million-second exposure. Even though the mirror is much smaller, because it's in space, the Hubble can get a resolution far better than much larger telescopes on the ground. Just as technology is making ground-based telescopes larger, so too are their plans for even larger space-based telescopes. The James Webb telescope is almost complete, and it is expected to be launched sometime in 2021. The web will be different from Hubble in several different ways. First, it will not orbit around the Earth. It will be placed in a stable gravity point called a Lagrange point, almost four times the distance from the moon. Unlike the Hubble, it will not

be constantly zipping around the planet every 95 minutes. This will allow for some very long single exposures. Second, the web will have a far larger light collecting area. The web's primary mirror will be 6.5 meters, with over 15 times the light collecting area. Finally, the web will have a large sun shield the size of a tennis court to block light from the sun. You may have noticed that 6.5 meters is far larger than the width of any rocket. The web will basically be folded into the world's most elaborate and expensive origami. It will take a full two weeks for the telescope to slowly unfold and a full month for it to get into its final place in space. All of the telescopes I've mentioned are collecting light in the visible or infrared parts of the spectrum. Once you get into

radio astronomy, you can have dishes that take up entire volcano calderas like the Eresibo telescope in Puerto Rico, and with interferometry, you can have telescopes all over the earth working in unison. Astronomy is a very exciting field right now. With the new telescopes which will be coming online in the next few years, we should expect discoveries which will rival anything we've seen thus far. Executive producer of Everything Everywhere Daily is James Mackle. Please remember to support the show over at patreon.com where you can get exclusive merchandise and to leave a review on Apple Podcasts.

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