when gas and dust collapsed under the
influence of gravity after the Big Bang.
However, the 150 globular clusters do not
rotate around the centre of the galaxy at
equal speed, and some rotate at a slightly
different angle. The clusters that follow the
disc were formed early, together with the
rest of the Milky Way. Those that do not
follow the disc, on the other hand, were
formed later. This can help establish which
parts of our galaxy were formed first.
The bump came first
When astronomer Denilso Camargo recently
published pictures of five newly-discovered
globular clusters, the astronomers of the
world paid attention. The globular clusters
are all located close to the bump at the
centre of the Milky Way. And the clusters
are 12.5-13.5 billion years old – all their
stars are metal-poor. The results are sur-
prising given that this type of globular
cluster is normally found much further
away from the centre of the Milky Way.
Metal-poor globular clusters at the
centre of the Milky Way indicate that the
central bump formed first, not the spiral
arms. The bump resembles a small, ellipti-
cal galaxy, so scientists are now trying to
work out if the Milky Way began its life with
another shape.
The next question is how the elliptical
galaxy was born. The newly found globular
clusters’ motions indicate that many galax-
ies collided to form a ‘Baby Milky Way’
which later developed spiral arms and
became the galaxy that we know today.
This theory conflicts with what astronomers
used to think: that the Milky Way’s exterior
is a fusion of small galaxies and that thebump developed at a later point in time.
The five new globular clusters indicate a
more chaotic past for the Milky Way than
scientists had previously believed.Life in space is older than Earth
The development of the galaxies is not just
a question of how stars form and large
structures develop. The very conditions of
life are at stake. When new stars form, so
do new planets. The new discovery of glob-
ular clusters shows that star formation was
common billions of years ago. Scientists
can also assume that more planets were
formed in this early period. More planets
means more chances of Earth-like planets.
And if life originates as soon as a planet can
support it, then the majority of life outside
Earth (if any) may have originated before
our Earth was even formed.Galaxies spin around each other
4
The momentum of the galaxies makes
them fly briefly past each other before
gravity unites them. The manoeuvre
stretches and twists the shapes of the galaxies.
Gas is scarce, and galaxies unite
5
The galaxies have now consumed
most of their gas to form stars.
The large movements have also
been curbed. Stars and planets slowly unite.‘Milkomeda’ dies
6
The material from the galaxies has
united into one large galaxy known
as Milkomeda. No more stars form,
so the galaxy is astronomically dead.Andromeda is about 2.5 million light
years from the Milky Way, approaching
at a speed of 400,000km/h.In 4 billion years In 5.1 billion years In 7 billion yearsNAS
A/E
SA& (^) S
HU
TTE
RST
OCK
The Milky Way Andromeda Star clouds Milkomeda
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