The universe’s history revealed in one composite photo

7e1e2230 new tsa cover image 1200x858 44 1200x858 - The universe’s history revealed in one composite photo

NASA describes the Hubble telescope photo as a “wide view of the evolving universe”, and “the most comprehensive history book” of the galaxies in our universe.

While the image looks like an ordinary shot of the night sky, allow us to point out those are about 265 000 galaxies you are looking at. And they stretch back through 13.3 billion years of time.

It is able to give us a snapshot view of the universe’s past because light from those galaxies, from all those billions of years ago, are only arriving at Earth now after crossing space for aeons.

The photo chronicles the universe’s evolutionary history in one sweeping view. The faintest and farthest galaxies are just one ten-billionth the brightness of what the human eye can see.

The full photo:

3d197196 universe jpeg - The universe’s history revealed in one composite photo
Astronomers have just assembled one of the most comprehensive portraits yet of the universe’s evolutionary history, based on a broad spectrum of observations by the Hubble Space Telescope and other space and ground-based telescopes. In particular, Hubble’s ultraviolet vision opens a new window on the evolving universe, tracking the birth of stars over the last 11 billion years back to the cosmos’ busiest star-forming period, about 3 billion years after the big bang. This photo encompasses a sea of approximately 15,000 galaxies — 12,000 of which are star-forming — widely distributed in time and space. This mosaic is 14 times the area of the Hubble Ultra Violet Ultra Deep Field released in 2014.
Credits: NASA, ESA, P. Oesch (University of Geneva), and M. Montes (University of New South Wales)

That may sound preposterous, but we often forget the true size of our universe. And it’s expanding all the time, too. What we see when we look up every night is just a tiny fraction.

Let’s look at this way: There are around 170 billion galaxies in the observable universe, spanning over a radius of 45.7 billion light years, according to Space.com.

Some spiral galaxies have more than a trillion stars. Some giant elliptical galaxies have 100 trillion stars. There are also tiny dwarf galaxies that have a significantly fewer number of stars.

So, there are about a septillion stars in the universe give or take a few billion. By the way, a septillion is a 1 with 24 zeros. It’s impressive when it’s all typed out: 1 000 000 000 000 000 000 000 000.

Watch: The Hubble Legacy Field Zoom-out

The septillion Space.com refers to, is according to the US short scale where a septillion is a trillion billion, a 1 with 24 zeroes. According to the British long scale, a septillion is a billion quintillion, a one followed by 42 billion.

Yes, I know. Don’t even get me started on the Afrikaans word miljard, which is a billion in Afrikaans, a 1 with nine zeroes or a thousand million. The same term in British English is a 1 with 12 zeroes, or a million million.

Actually, I may be wrong; it’s hard to keep track of the zeroes. This kind person tried to explain it.

Back to how many stars we can see when we look up at the night sky? Oh, only about 5 000 or so. Regardless of our conclusion about how many zeroes is in a septillion, it’s a lot more zeroes than in 5 000.

Most of the stars you see at night are in our galaxy, the Milky Way. But some of those feint dots you see are not stars. They are entire galaxies.

In fact, let’s stop worrying about the zeroes and galaxies. Let’s just watch this size comparison to get a grasp of how big the universe actually is:

Watch: 3D size comparison of the Universe

ALso read – Hubble telescope unveils photo to celebrate 29th birthday 

The Hubble Legacy Field extrapolated the Hubble Telescope’s data from the last 29 years. It combines observation taken by Hubble’s deep-field surveys and captured the key features.

Garth Illingworth of the University of California, Santa Cruz explains that the team “have gone wider than in previous surveys and included more distant galaxies in this dataset.” She adds:

“This one image contains the full history of the growth of galaxies in the universe, from their time as ‘infants’ to when they grew into fully fledged ‘adults.’”

Deep-field views such as this help astronomers trace the expansion of the universe, with the galaxies showing when the chemical elements originated and led to the conditions that made life possible

The Hubble telescope won’t be able to top this, as it is has reached the limits of its capability. This image and dataset will only be surpassed when new telescopes are launched.

Hubble recently celebrated its 29th year in operation. Every year, the telescopes sents back a special anniversary image. The image this year depicted the Southern Crab Nebula.

68ad2c9e copy of tsa cover image 1200x858 78 - The universe’s history revealed in one composite photo
The Southern Crab Nebula. Photo: NASA, ESA, and STScI

Leave a Reply

Your email address will not be published. Required fields are marked *