For the past 400 years, telescopes have transformed our knowledge of the universe. Each era sees deeper and further than the one before it. We are on the verge of answering some of the most haunting questions. Are we alone in the universe? Are there other Earth-like planets out there?
IN THE BEGINNING:
Since the ancients looked up at the sky, it was obvious that everything revolved around us. Problem was, that model got a little complicated. If you observe the planets over weeks and months, they were making little loops, not just going around in beautiful arcs. Copernicus said the model was much simpler with the sun in the middle. Born in 1473, he had no way to prove his theory because he had no way to make the observation. Afraid of clashing with the church and other astronomers, he did not publish his theory until the year he died.
Fifty years later, in 1609, an Italian scientist hears about a Dutch invention that makes objects appear closer. Within a day, Galileo makes his own telescope and observes mountains and craters on the moon; he sees the Milky Way; he looked at Jupiter and saw four pinpricks of light. Every night, the pinpricks are changing. He realized these were not stars but moons going around Jupiter.
Everything was supposed to revolve around the Earth; here was proof that it wasn’t. He realizes the ancients were wrong, the church was wrong, Copernicus was right.
The whole world collapses into this beautiful simplicity and we are going around the sun.
Two lenses make up a telescope. The Webb telescope is 100 times more powerful than the Hubble. Galileo’s telescope gathered 100 times more light than the human eye; the James Webb telescope gathers 1,000,000 times more light than the human eye.
Webb doesn’t use Galileo’s lenses but the technique of a different genius. By the time he was 26 in 1668, Isaac Newton had invented calculus and the law of gravitation. He had also devised a new kind of telescope—the reflector. If you used a mirror, not a lens, all the wavelengths get reflected off the mirror in exactly the same way, so all the colors come through to exactly the same perfect focus and allowed us to make bigger and bigger telescopes that collect more and more light and see further and further into the universe. The most powerful telescopes have used this basic design, i.e. the Great Palomar 200-inch, Keck 10-meter, Hubble Space Telescope, and James Webb Space Telescope. The James Webb can easily detect a human’s radiant heat, about 80 to 100 watts.
Throughout the 18th and 19th centuries, most astronomers believed the Milky Way was the entire universe. But some strange fuzzy objects were puzzling. If they were outside the Milky Way, it would mean the universe was a lot bigger than we thought. At that time, there was a Great Debate in astronomy. You can Google the term “Great Debate,” thinking it’s a Supreme Court case or other historical argument, but it’s a debate between two astronomers trying to resolve what our place in the universe is. They couldn’t decide because they had no evidence. Settling the great debate would require the biggest telescope ever attempted and 4 ½ tons of smashed French wine bottles.
THE BIG EYE:
When the 18 mirror segments of the James Webb are finally mounted on the carbon-fiber back plane, they will create a near-perfect optical surface over 21 feet across. 100 years ago, at the time of the Great Debate, it was difficult to make a mirror just 8 feet across. In 1908, the Saint-Gobain Glass Factory cast a 100-inch mirror out of 4½ tons of bottle glass—the largest ever attempted. The mirror was full of bubbles but was shipped to California regardless where an American, George Ellery Hale, was raising millions to build a new observatory on Mt. Wilson overlooking Los Angeles. The master polisher complained bitterly, but the mirror proved good enough to revolutionize our conception of the universe and would force Albert Einstein to revise his equations.
Despite promising his dying father he would become a lawyer, after Edwin Hubble was discharged form the army after World War I, he went to Mt. Wilson and spent his time looking at the night sky. Four years later in October 1923, something caught his eye. He began using the most powerful telescope of its time, the 100-inch. One star in particular is changing its brightness about every month. This one beacon is blinking while the other stars remain the same in his photographic plates. He writes, “V.A.R.!” If you know the brightness of an object when it’s nearby, you can figure out the distance to a similar object by measuring how much dimmer it is. That’s what Hubble did with the variable star in Andromeda. He discovered Andromeda couldn’t be part of the Milky Way and was in fact, 2½ million light-years away. The great challenge is just figuring out how far away everything is, getting that depth dimension; depth perception is only possible with these telescopes. Hubble looked at one single star, variable 1, and immediately answers the question, “Are we the only galaxy? Or is the universe teeming with them?”
Hubble also showed the universe was expanding; Einstein had adjusted his equations to make it static, a mistake he called it his biggest blunder. The expanding universe was revelation because it implied an earlier time when the galaxies were closer together. It implied a Big Bang.
The next obvious step was to build a 200-inch. Palomar became the ultimate observing machine, they called it “the big eye.” But it had one fundamental problem: it was sitting here on Earth. The air that we breathe makes the images from stars that we’re observing blurry. So Lyman Spitzer suggested taking a giant telescope and putting it in space, above the atmosphere of the Earth. He proposed space telescopes in 1948. It would take more that 40 years, but his dream of a telescope in space finally came true on April 24, 1990.
The first images from the Hubble came back blurry. At the edge of the 94-inch mirror, the mirror was off by a fraction of the width of a human hair. Fortunately, Hubble is only 8 minutes away. Astronauts went back several times to do so. The new images were better than we could’ve imagined. Witnessing births and deaths of stars, finding black holes at the center of galaxies, measuring the age of the universe, confirming the existence of dark energy.
Hubble’s most inspiring image is perhaps the long time exposure known as “the deep field.” Hubble Deep Field was a pure discovery. The second director of the HST said, “I wonder what happens if we just stared at a completely blank piece of sky and just see what we find.” He stared at that spot for 10 days; man thought he was crazy and wasting telescope time. To everyone’s surprise, out of that single point of sky came 10,000 galaxies. Only three of those points of light are stars; every other point of light in that image is a galaxy.
There are roughly 100 billion stars in the galaxy. 1022 stars in the observable galaxies. We now need a telescope that can see beyond the visible.
As the universe is expanding and stretching across space and time, its light is being redshifted and shifted out of the view of the HST. Those galaxies are so far away from us that as light travels through space, and space is expanding because the universe is expanding, the light gets redshifted, so it changes from blue light into red light as it travels through space. It’s so far away from us and so far back in time that its light only reaches us via infrared wavelengths. The James Webb is going to penetrate beyond what the Hubble can see and give us infrared eyes.
In order to detect infrared signature, the James Webb needs to be very cold, or it’ll only detect itself. In space, the electronics and the sun will heat you up. We don’t want to blind ourselves, so the James Webb will be considerable distanced from the Earth and the sun. This drives us to orbit the so-called “Earth sun,” L2 point, a million miles away from the Earth and the sun. Out at L2, a repairman can’t make a house call.
The James Webb weights 6 metric tons, down from 300. We had to create this origami telescope. From its vantage point at L2, Webb will do more than see the first galaxies. It will also peer through the dust clouds to see where stars are born, and it will investigate small objects of particular importance for us-exoplanets.
TINY (BUT MEASURABLE):
There are five naked-eye planets: Mercury, Venus, Mars, Jupiter, Saturn. With telescopes, three more were discovered-Uranus, Neptune, Pluto. Then Pluto got demoted. The first exoplanets were discovered from the ground. March 7, 2009, the Kepler Space Telescope went up. Nowadays, the best way to find planets is by the transit technique. If you’re lucky, the planet will orbit such that it passes in front of the stars. Then the starlight drops by a tiny amount. If it’s a Jupiter-sized planet (Jupiter is a 10th the size of our sun), it’ll block out 1/100th of the brightness of the star. If it’s Earth, it’s 1/10,000th. Tiny, but measurable.
The segmented mirror of the Keck Telescope (Mauna Kea, Hawaii) was the model for Webb and points the way towards larger telescopes on the ground and in space that will be needed to probe the atmospheres of exoplanets for signs of life, i.e. water vapor, carbon dioxide, and gasses that don’t belong. Oxygen wouldn’t exist on earth without photosynthetic plants. The 10 most common elements in our bodies are the 10 most abundant chemical elements in the universe.
We are building telescopes not just to satisfy our curiosity, but ultimately for our survival. We’re building a telescope in Chile to scan the sky with a massive camera that will be able to characterize asteroids, so we can get a heads-up if one is coming our way. We’re building a telescope on Haleakala in Maui—a four-meter reflecting telescope—just to look at the sun. Our sun is about a third of the way through its life. When our sun is 10% older, it’s going to be 10% brighter. Our atmosphere’s going to start drying out. When the sun is 30% older, it’ll be 40% brighter, enough to dry out the oceans on our planet. Eventually, the sun will expand and balloon as it runs out of hydrogen. Its outer layers are going to expand to a distance that encompasses the orbit of the Earth around the sun. So it’s going to obliterate the inner solar system. So it’s inevitable that we have to leave our home. (I personally think our species will be extinct LONG before that happens).