The ancient Greeks would look up and wonder if there was life among the stars. The James Webb Space Telescope (JWST) will soon be able to answer the question that has fascinated mankind since we began to walk erect. Life on Earth is about to change in a very profound and provocative way.
The purpose of a telescope is to gather more light than the human eye is capable of, allowing us to see things that would otherwise be invisible. Therefore, the power of a telescope is directly related to how large the light-gathering lens or mirror is. In school, the typical telescope lens is only about three inches. Unfortunately, a telescope that small does not have a motor to slowly rotate the telescope to compensate for the spinning of the earth. You may see a star, but it only remains in your field of view for a few seconds. Then, it’s gone. A serious amateur astronomer will want a telescope with an eleven or twelve-inch mirror, and a computer controlled guidance system that will keep the object you are interested in, centered in your field of view. It may also allow you to attach a camera so you can take photos of the stars and galaxies that you find.
Of course, professional astronomers want the largest lenses and mirrors possible. The McDonald Observatory in Fort Davis, Texas has several telescopes that are used during their frequent “star parties”. They have mirrors that measure 20, 30, and 36 inches across. They also have the Otto-Struve telescope that was built in 1939 which has an 82-inch mirror. It was the second largest telescope in the world at that time. Even more impressive is the Harlan J. Smith telescope with a mirror that measures 107 inches across.
But the size of the mirror isn’t the only factor that determines what a telescope can see. When you look at the bottom of a swimming pool, it looks like the painted lane lines are wiggling back and forth. They’re not, of course. The surface of the water has small waves and ripples that refract the light to make the lines appear to wiggle. In the same way, stars do not “twinkle”. The atmosphere above the earth changes the path of light reaching our eyes, so the light from the stars appears to be unstable. You don’t have to be extremely clever to realize that you’ll see the sky more clearly if you can minimize the effect of the Earth’s atmosphere.
The twin Keck Observatory telescopes are the world’s most scientifically productive optical and infrared telescopes. Each telescope weighs 300 tons and operates with nanometer precision. The telescopes’ primary mirrors are 10-meters in diameter (393.7 inches) and are each composed of 36 hexagonal segments that work in concert as a single piece of reflective glass. This two-telescope astronomical observatory is at an elevation of 13,600 feet near the summit of Mauna Kea in the U.S. state of Hawaii. When they were completed in 1993, they were the largest astronomical telescopes in the world. They are currently the 3rd and 4th largest.
Of course, the world-famous Hubble Space Telescope orbits 336 miles above the surface of the Earth, thereby eliminating the problem with the atmosphere all together. The Hubble mirror is “only” 7 feet, 10 inches (94 inches) across, but it has taught us more about the universe we live in than almost any other telescope that has ever been made. One major accomplishment is the The Hubble Deep Field (HDF) image of a small region in the constellation Ursa Major. It covers an area showing one 24-millionth of the whole sky. The field is so small that only a few foreground stars in the Milky Way lie within it; thus, almost all of the 3,000 objects in the image are galaxies, some of which are among the youngest and most distant known. By revealing such large numbers of very young galaxies, the HDF has become a landmark image in the study of the early universe. It wasn’t that long ago that astronomers thought that our Milky Way Galaxy was the total extent of the universe.
The James Webb Space Telescope was launched Christmas Day, 2021, just a few months ago. It will be located at Lagrange Point #2, which is one million miles away from the earth, opposite the sun. This is four times further from the Earth than the moon. The telescope will not orbit the Earth. Instead, it will orbit the Sun while remaining relatively close to the Earth. However at that distance, radio signals (traveling at the speed of light) will take 5.36 seconds to reach the telescope. The JWST will not bother with visible light, but will gather light at longer infrared wavelengths. We experience infrared as heat, and so the ten billion dollar telescope must be protected from the heat of the Sun, the Earth, and the Moon. Much like someone sitting under an umbrella at the beach, the JWST has a huge solar shield that will isolate it from temperatures that would otherwise blind the telescope, similar to you driving west looking into the setting sun. The solar shield looks like five layers of very thin aluminum foil, which had to be carefully deployed soon after the telescope left the launch pad. The telescope has 18 gold-plated mirrors that must be carefully focused to work together to create a single image. The combined diameter of the mirrors is 21 feet, or 252 inches. (Hubble is only 94 inches.)
Modern astronomers have wondered if there were planets in the universe, other than the eight we know are orbiting our Sun. Scientists have since found nearly 5,000 “exo-planets” orbiting other stars in our Milky Way galaxy. Hubble isn’t powerful enough to tell us anything except that a planet exists. The James Webb will be able to look at those planets to determine if they have an atmosphere, and what that atmosphere is composed of. If scientists find evidence of oxygen, carbon dioxide, and water, then chances are good that life exists somewhere other than the planet Earth.
Of course, scientists have no way to know what we will discover in the future. Scientific discoveries are almost always a surprise. However, the James Webb will definitely provide us with information that will disturb many people who are unwilling to change their perceptions of reality. In 1633 Galileo was excommunicated from the Catholic church for being “vehemently suspect of heresy and defending an opinion as probable after it has been declared contrary to Holy Scripture.” He died in 1642 after spending the last nine years of his life in prison. Fortunately for Galileo, in 1992 – only 359 years later – Pope John Paul II acknowledged that the Church had erred in condemning Galileo for asserting that the Earth revolves around the Sun. Sadly, there will be people who continue to insist that the Earth is flat and only 6,000 years old, in spite of the overwhelming evidence to the contrary. Nothing can be done to educate those people. They are not worth talking to.
I, on the other hand, am filled with childlike excitement wondering what we will learn about the universe. I only wish Carl Sagan was still alive to enjoy this amazing moment in time. If you don’t want to be left behind intellectually, I highly recommend that you watch Sagan’s 1980 video series, Cosmos: A Personal Voyage. You won’t regret it.