A jewel-filled photo that's been said to be the deepest photo of the universe ever taken was released on July 12.
In addition to looking farther across space than any observatory before it, the James Webb Space Telescope can look back in time to when the universe was only a few billion years old.
What is it that this can be done? How can it look like it's in the past? The nature of light isn't magic.
Telescopes can do things. NASA scientists said looking out in space is similar to looking back in time. Light needs time to travel across the vast distances of space to get to us.
It takes time to look at the light you see, from the twinkling stars to the glow from your desk lamp. 670 million mph (1 billion km/h) is the speed of light, so you won't notice it when it travels from one place to another.
You can see light that has traveled a long way to reach you when you look at objects that are millions of miles away.
The sun can be taken as an example. The home star is an average of 93 million miles away. Light travels from the sun to Earth in about 20 seconds. Although you should never look directly at the sun, you can see it as it appeared 8 minutes ago, not as it is right now.
Astronomy uses light-years, rather than miles or kilometers, to measure great distances in space because of the importance of the speed of light. A light-year is the distance that light can travel in a year. The North Star is about 323 light-years away from Earth. Light that's more than 300 years old can be seen whenever you see this star.
You don't need a fancy telescope to see back in time with your own eyes. Astronomers need telescopes to look far into the past. It's possible to see visible light coming from many millions of light-years away, but it can also pick up wavelengths of light that are invisible to humans.
Humans emit heat as a function of their body temperature. The naked eye cannot see this energy. Some of the hardest-to- find objects in the universe can be seen with the correct equipment. NASA says that because of the longer wavelength of the radiation, it can be passed through dense, dusty regions of space. Many stars and galaxies are too far, faint or obscured to see as visible light emits heat energy.
This is one of the greatest tricks of all time. The telescope can see light that was emitted more than 13 billion years ago by the most ancient stars in the universe.
That's how it took its famous deep field image, and that's how it will try to look even further back in time, to the first few hundred million years after the Bigbang. The stars that the telescope will reveal may be long-dead today, but as their ancient light makes the lengthy journey across the universe, they are treated to a one-of-a-kind time travel display.
It was originally published on Live Science
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