Science_Illustrated_Australia_-_Issue70_2019

T

he Big Bang is still resounding

through the universe. Clouds

of gas and dust collapse under

their own gravity, turning into

the burning infernos that we

call stars. Around them, in the remnants,

planets form. A large cloud of stars, planets,

and more gas and dust are united by gravity

into a huge spiral. Many smaller clouds join

over billions of years, and finally a bump

emerges at the centre of the spiral. The

Milky Way has been born.

This is how most astronomers know

the story of our young galaxy. But recently

they were shocked by new discoveries of

globular clusters – ancient groups of stars

• which reveal a more violent and surprising
  history. It now seems that many galaxies,

With a new, huge telescope, we will see galaxies far more

remote than we can today. And as their light has travelled

further, we will see galaxies earlier in their formation

process. So we might see the universe’s oldest galaxies.

The ELT telescope will be able to peer deeper into

the universe as its diameter (no less than 39 metres)

will detect much weaker light than is possible today.

It can also produce images of a very high resolution.

Scientists plan to make some of the first observations

with the telescope in 2025.

Super telescope to fi nd

the oldest galaxies

The European Extremely Large Telescope (ELT) will make

observations at 16 times higher resolution than is

possible with the Hubble telescope.

The new huge ELT telescope

will allow us to peer

deeper into the universe

than ever before.

bringing their own stars, planets, gas and

dust, collided at inconceivable speeds in

violent reactions that formed the Milky

Way in the reverse order of what we used

to think: the bump at the centre came first.

The new star discoveries may even help

astronomers determine the likelihood of

life on planets in other solar systems.

One galaxy becomes millions

Our Sun is just one star among hundreds of

billions that make up the Milky Way,

together with gas and dust. Our galaxy

orbits other galaxies in galaxy clusters, and

these orbit each other in superclusters, the

biggest known structures in the universe.

The most recent calculations show that

some 10 million superclusters include two

trillion galaxies in the visible universe. And

yet we need not go far back in history

before scientists’ best estimate was... one.

About 100 years ago, astronomers

believed that the universe con-

sisted only of our own

galaxy, the Milky Way.

Experts thought that the galaxy included

stars and planets plus dust and gas united

in nebulas.

Then in 1923, Edwin Hubble discovered

nebulas outside the Milky Way, proving the

existence of at least several galaxies.

Immediately after Hubble’s revelation,

astronomers began to research how these

different galaxies formed, and why they

don’t all look the same. Since 1923, they

have been trying to solve the mysteries of

galaxy birth and development by studying

the most ancient galaxies in the universe.

Light shows young galaxies

In basic terms, all astronomy involves

collecting light by means of telescopes and

then analysing where it comes from – or

rather how far it has come. Light travels at

a speed of 299,792,458 metres/second, and

the universe is so big that light from

remote galaxies has travelled for billions of

years to reach our telescopes. The deeper

astronomers look into the universe, the

further back in time they peer.

HUBBLE ELT

BIRTH

ESO

/L.

CAL

ÇAD

A

The galaxies were born after the

Big Bang, when material in the universe

collected into stars and planets.

SPACE GALAXIES