The James Webb Space Telescope (JWST) made history last July 12, by releasing its first image, a gem-filled image that has been described as the deepest image of the universe ever taken.
Besides looking at the farthest point across space ever observed, the James Webb Space Telescope has another trick in its mirrors. It can look back in time more than any other telescope, and observe distant stars and galaxies, as they appeared 13.5 billion years ago, not so long ago. The beginning of the known universe.
How is this possible? How can a machine look “back in time”? It’s not magic, it’s just the nature of light.
“Telescopes can be time machines,” NASA scientists explained on WebTelescope.org, in a report published by Russia Today, yesterday. Looking into space is like looking back in time. It sounds magical, but it is actually very simple, light needs time to travel across vast distances of space to reach us.”
The Sun is located an average of 93 million miles (150 million km) away, which means that light takes regarding 8 minutes and 20 seconds to travel from the Sun to Earth. Scientists explain: “When we look at the sun (although you should not be looking at the sun directly), you see it as it appeared more than 8 minutes ago, not as it appears now – in other words, you are looking 8 minutes in the past.”
The speed of light is so important to astronomy that scientists prefer to use light years, rather than miles or kilometers, to measure great distances in space. A light year is the distance light can travel in one year: regarding 5.88 trillion miles, or 9.46 trillion kilometers, for example, the northern star, Polaris, is located regarding 323 light years from Earth. When you see this star, you see a light that is more than 300 years old.
To look really far into the past, astronomers need telescopes like the JWST. Not only can the James Telescope zoom in on distant galaxies to observe visible light coming from millions of light years away, it can also pick up wavelengths of light invisible to the human eye, such as infrared waves.
The telescope can roam the dusty regions of space to study the light that was emitted more than 13 billion years ago by the oldest stars and galaxies in the universe.
