The Times Australia
The Times World News

.
The Times Real Estate

.

Is the James Webb Space Telescope finding the furthest, oldest, youngest or first galaxies? An astronomer explains

  • Written by Michael J. I. Brown, Associate Professor in Astronomy, Monash University
Is the James Webb Space Telescope finding the furthest, oldest, youngest or first galaxies? An astronomer explains

We’ve now seen the first data from the James Webb Space Telescope[1]. It has observed the atmospheres of distant planets, groups of nearby galaxies, galaxy light bent by unseen dark matter, and clouds of gas and dust in stellar nurseries.

We have also seen headlines claiming Webb has found “the oldest galaxies we have ever seen[2]”, but what does that mean?

I’m a professional astronomer who studies old galaxies[3], and even I find this a little puzzling.

Looking far, looking back

One of the key science goals of Webb[4] is to peer back in time and observe the early Universe. Webb can do this because, like all telescopes, it is a time machine.

Light travels at 300,000 kilometres per second, so when we look at the Moon we are seeing it as it was a second ago. As the planets of our Solar System are millions or billions of kilometres away, we see them as they were minutes or hours ago.

Going further still, when we look at distant galaxies with telescopes we are often looking at light that has taken millions or billions of years to reach us. This means we are seeing these galaxies as they were millions or billions of years ago.

Read more: When you look up, how far back in time do you see?[5]

What has James Webb seen?

The James Webb Space Telescope is able to see more distant galaxies than other telescopes, including the Hubble Space Telescope.

Like Hubble it is above the glowing and turbulent atmosphere of the Earth. However, whereas Hubble has a 2.3 metre mirror for focusing light, Webb has a vast 6.5 metre mirror formed from 18 hexagonal segments. Finally, Webb is optimised to detect infrared light, which is what we observe from the most distant galaxies as the expansion of the Universe has stretched ultraviolet and infrared light into the infrared.

James Webb has a vast segmented mirror.
James Webb has a vast segmented mirror that allows it to look into the distant past. NASA

Among the first data obtained by Webb were infrared images looking towards a cluster of galaxies called SMACS 0723[6].

The light from SMACS 0723 has taken 4.6 billion years to reach us, so we are seeing it as it was 4.6 billion years ago. That’s slightly older than the Sun and the Earth, which only formed 4.56 billion years ago.

In recent weeks, galaxies far beyond SMACS 0723 have gained attention. Webb has detected a number of galaxies in the direction of SMACS 0723 and other regions[7] that could be so distant their light has taken 13.5 billion years to reach us.

I say “could” because more data will be needed to absolutely confirm their distances, but some of these galaxies are very compelling[8] candidates (others less so[9]).

As the light has taken 13.5 billion years to reach us, we are seeing these galaxies as they were 13.5 billion years ago. The Universe itself is 13.8 billion years old, so we could be seeing galaxies as they were just a few hundred million years after the Big Bang[10].

Maise's galaxy Maisie’s Galaxy may be one of the most distant celestial objects yet observed. Steve Finkelstein/Twitter

Young, old or early?

While these very distant galaxies have been advertised as the “oldest galaxies[11]”, I find this a little confusing. We are actually seeing these galaxies as they appeared when they were very young, perhaps a hundred million years old or so.

It is true that these galaxies will be old now, but our own Milky Way galaxy is very old now too. While our Sun is 4.56 billion years old, many stars in our galaxy are 10 billion years old and some stars in the Milky Way are 13 billion years old[12].

The Milky Way is billions of years old. The galaxy we live in, the Milky Way, is billions of years old. Caroline Jones/Flickr

Furthermore, the very distant galaxies Webb has spotted will look very different today. Galaxies grow by acquiring gas and dark matter, forming new stars and merging with other galaxies.

A small galaxy that was vigorously forming stars soon after the Big Bang may have ended up being the seed of a galaxy that today is very massive and stopped forming stars long ago. That small galaxy and its old stars could also have ended up being just part of a larger galaxy formed relatively recently by merging galaxies together.

A record set to fall

So should we call these most distant galaxies young or old? Perhaps neither.

James Webb is seeing the earliest galaxies yet observed – some of the first galaxies that formed soon after the Big Bang.

I have thrown in one last caveat – “yet observed”. Webb has only just begun its mission[13], and current analyses are based on data collected over hours.

With days’ worth of data, Webb will push its view out to fainter and further objects, and see yet-more-distant galaxies. The record for the most distant and thus earliest observed galaxy will probably tumble a few times before the year is out.

References

  1. ^ first data from the James Webb Space Telescope (www.nasa.gov)
  2. ^ the oldest galaxies we have ever seen (www.newscientist.com)
  3. ^ studies old galaxies (ui.adsabs.harvard.edu)
  4. ^ science goals of Webb (webb.nasa.gov)
  5. ^ When you look up, how far back in time do you see? (theconversation.com)
  6. ^ SMACS 0723 (www.nasa.gov)
  7. ^ other regions (ceers.github.io)
  8. ^ very compelling (twitter.com)
  9. ^ less so (twitter.com)
  10. ^ Big Bang (theconversation.com)
  11. ^ oldest galaxies (www.dailymail.co.uk)
  12. ^ 13 billion years old (www.anu.edu.au)
  13. ^ mission (webb.nasa.gov)

Read more https://theconversation.com/is-the-james-webb-space-telescope-finding-the-furthest-oldest-youngest-or-first-galaxies-an-astronomer-explains-187915

The Times Features

Best Deals on Home Furniture Online

Key Highlights Discover the best deals on high-quality outdoor furniture online. Transform your outdoor space into a stylish and comfortable oasis. Explore a wide range of d...

Discover the Best Women's Jumpers for Every Season

Key Highlights Explore lightweight jumpers for spring and summer, ensuring breathability and ease. Wrap up warm with cozy wool jumpers for the chilly autumn and winter season...

Uncover the Elegance of Gorgeous Diamond Tennis Necklaces

Key Highlights Diamond tennis necklaces are a timeless piece of jewelry that exudes elegance and sophistication. They feature a continuous line of brilliant-cut diamonds, cre...

Dental Implants vs. Dentures: Which Is Better for You?

When it comes to replacing missing teeth, two of the most common options are dental implants and dentures. Both have their advantages and disadvantages, so choosing between them ...

What Neck Pain Really Means (And Why It’s More Than Just Poor Posture)

Neck pain is often brushed off as something temporary — a tight spot after a long day at the desk or a poor night’s sleep. But when the discomfort keeps returning, it could be a ...

The Work of Gosha Rubchinskiy: Fashion, Culture, and Youth

From Designer to Cultural Architect Gosha Rubchinskiy is not just a fashion designer—he's a cultural force. Born in Moscow in 1984, Rubchinskiy began his career in fashion in t...

Times Magazine

The Essential Guide to Transforming Office Spaces for Maximum Efficiency

Why Office Fitouts MatterA well-designed office can make all the difference in productivity, employee satisfaction, and client impressions. Businesses of all sizes are investing in updated office spaces to create environments that foster collaborat...

The A/B Testing Revolution: How AI Optimized Landing Pages Without Human Input

A/B testing was always integral to the web-based marketing world. Was there a button that converted better? Marketing could pit one against the other and see which option worked better. This was always through human observation, and over time, as d...

Using Countdown Timers in Email: Do They Really Increase Conversions?

In a world that's always on, where marketers are attempting to entice a subscriber and get them to convert on the same screen with one email, the power of urgency is sometimes the essential element needed. One of the most popular ways to create urg...

Types of Software Consultants

In today's technology-driven world, businesses often seek the expertise of software consultants to navigate complex software needs. There are several types of software consultants, including solution architects, project managers, and user experienc...

CWU Assistive Tech Hub is Changing Lives: Win a Free Rollator Walker This Easter!

🌟 Mobility. Independence. Community. All in One. This Easter, the CWU Assistive Tech Hub is pleased to support the Banyule community by giving away a rollator walker. The giveaway will take place during the Macleod Village Easter Egg Hunt & Ma...

"Eternal Nurture" by Cara Barilla: A Timeless Collection of Wisdom and Healing

Renowned Sydney-born author and educator Cara Barilla has released her latest book, Eternal Nurture, a profound collection of inspirational quotes designed to support mindfulness, emotional healing, and personal growth. With a deep commitment to ...

LayBy Shopping