The James Webb telescope will let astronomers peer further into the past than ever before. The Webb’s primary lens system’s 18 gold plated lens segments will be part of an orbiting optical infrared space observatory. The Webb telescope will capture infrared light from a distance of over 13 billion light-years away from us. Distances in space are measured by how long it takes light to travel. Our moon is 1.3 light-seconds away; the nearest star in our Milky Way galaxy is 4 light-years away; and our nearest neighboring galaxy, the Andromeda, is about 2.5 million light-years away. This means that the images captured from light traveling from the Andromeda galaxy happened two and a half million years in the past.
What do astronomers hope to see? They hope to capture light from the first stars and galaxies of the universe. And they want to study and search for signs of life on exoplanets (planets that orbit stars other than our sun). According to NASA, the Webb telescope orbiting in deep space “… will allow scientists to look at the early days of our universe and see what it was like about 200 million years after the Big Bang.”
Why infrared? To detect bodies of matter that are cool, and therefore aren’t high energy and emitting visible brightness, but nevertheless, radiate in the infrared. Another reason for infrared detectors in space is that the longer wavelengths of infrared light more easily escape dust clouds, unlike visible light that gets trapped. The Webb telescope will see the objects that emit light from inside the enormous dust and clouds of a nebula. How? Nebulae are interstellar nurseries for new stars. Infrared wavelengths of light will reveal the first stars and galaxies in the early universe after the big bang. Detecting infrared in space is better than visible light because of a process called cosmological redshifting, where light is stretched as the universe expands, so light emissions from stars in shorter ultraviolet and visible wavelengths are stretched to the longer wavelengths of infrared light by the time it reaches the Webb telescope detectors. Capturing these emitted and reflected wavelengths from space will allow scientists to observe distant galaxies and the early universe’s history. The hope is to answer questions about the first stars, how our universe formed, how galaxies evolved and provide answers about dark matter, energy and black holes. Lenses come in many forms; some let us see into the micro-universe, others let us see visible light and the world around us, and the lens system of the Webb telescope allows us to see into the distant past.
• Deborah Kotob
Pro to Pro Director