NASA talks about a “magic” space telescope

The James Webb Space Telescope continues to search deep into the universe. It’s like looking back. Why JWST is a “time machine”.

BALTIMORE – For several months now, the James Webb Space Telescope (JWST) has been providing scientists with data for their research, and stunning images of the universe are published regularly. It is said over and over again that the James Webb space telescope can “look into the past” or even a “time machine” that can look back almost to the Big Bang.

NASA also wrote about it James Webb Telescope website: “Telescopes can be time machines. Looking into space is like looking into the past.” But how is that possible? In fact, you don’t need a $10 billion telescope located 1.5 million kilometers from Earth in space to see the past. Any human eye can do that. NASA explains: “It sounds magical, but it’s actually very simple: light takes time to travel long distances in space and reach us.”

Nothing moves faster than light – every eye looks into the past of the universe

Fortunately, light travels very quickly – in fact, nothing moves faster than light. In a vacuum, light travels at 299,792,458 meters per second (about 1.08 billion km/h) – the speed of light. Because it’s so fast, you won’t notice the light moving in everyday life. If you turn on the flashlight, the light is instantly there—it travels so quickly from the flashlight to the human eye that you don’t even notice it. However, you are actually looking into the past: you see the light as it was a split second ago.

It becomes clearer if you take the moon or the sun as an example. There is about 390,000 km between the Earth’s satellite and our planet – it takes about 1.3 seconds for moonlight to cover this distance. So if you look at the full moon in the sky, you will see it as it appeared 1.3 seconds earlier. The Sun is about 150 million kilometers from Earth – it takes light eight minutes and 20 seconds to travel that distance. If you look at the sun (for safety reasons, you should only do so with proper eye protection), you look past just over eight minutes.

Light takes time to reach the Earth from great distances

What is true of the Moon and the Sun is also true of all other celestial bodies in our universe: their light takes time to reach Earth. The closest star to Earth, Proxima Centauri, is 4,246 light-years away, so we see it as it appeared about four years ago. Does it still exist today? You can only say that in four years, when the light that radiates today has reached Earth – or not.

The farther a celestial body is from Earth, the farther back you look. Earth’s nearest neighbor galaxy, the Andromeda Galaxy, is about two and a half million light-years away. The Virgo Cluster of galaxies, a group of galaxies in our cosmic neighborhood, lies about 60 million light-years away from the Milky Way.

The light we see from these galaxies was emitted today when the age of the dinosaurs on Earth ended. If you reverse the perspective, an interesting approach emerges: If life in the Virgo galaxy cluster is looking down through a telescope, it’s looking at a planet populated by dinosaurs and other prehistoric reptiles — humans not yet there.

The James Webb telescope as the universe’s “time machine”.

But back to the James Webb Space Telescope. The large telescope is equipped to look especially far into the past. This works mainly because the telescope operates in the infrared range. Many stars and galaxies cannot be seen with the naked eye or small telescopes simply because they are too far away and their visible light is no longer perceptible. Therefore, the James Webb telescope works in the infrared range of the spectrum. Infrared has a longer wavelength than visible light and can therefore penetrate dense, dusty areas.

satellite newsletter

Subscribe to the free space newsletter and stay informed.

JWST is always able to look far into the past and see light that has been traveling in space for over 13 billion years. In this way, the researchers want to go back to the first hundreds of millions of years after the Big Bang. They’re already on the right track: The James Webb Space Telescope has already detected some of the oldest galaxies in the universe – they actually existed between 325 and 460 million years after the Big Bang. (unpaid bill)