• Question: How is a milky way formed?

    Asked by sarah2013xxx to Colm, Eoin, Joseph, Lauren, Stephen on 18 Nov 2013.
    • Photo: colm bracken

      colm bracken answered on 18 Nov 2013:

      The Milkyway galaxy is called a spiral galaxy and it forms in a similar way that new star systems form, but on a much larger scale. New measurements of the cosmic microwave background radiation are showing us that some areas of space were more dense than others after the big bang. In these denser regions large amounts of matter started to collect. Stars had already started shining at this time so stars would have been orbiting around these dense regions with more and more matter being collected. Eventually so much mass would be collected in the centre that a blackhole would form. More and more mass would feed this blackhole making it larger and larger, but some of the stars and matter would occupy stable orbits around the blackhole and further out. These orbits and the whole spinning motion give rise to the spiral design that we see in these types of galaxies, the same way we observe a spiral as water spins when it goes down a drain. A spiral is just one of those naturally arising designs we see throughout nature, from a tiny snails shell to the biggest galaxies. Nature seems to land of the same designs again and again!

    • Photo: Joseph Roche

      Joseph Roche answered on 18 Nov 2013:

      Layers of chocolate-malt nougat topped with caramel and covered with milk chocolate.

    • Photo: Eoin O Colgain

      Eoin O Colgain answered on 19 Nov 2013:

      At such large length scales everything happens because of gravity. This may be a little surprising because this is, believe it or not, the weakest force we know.

    • Photo: Lauren Mc Keown

      Lauren Mc Keown answered on 22 Nov 2013:

      After the Big Bang, the Universe was cooling and a gas spread throughout. Small instabilities or irregularities in the medium allowed the gas to clump or coalesce into large scale clumps, collapsing and igniting nuclear fusion as it heated up and formed stars. As the guys said, gravity allowed these stars to come together in large groups called globular clusters. These clusters date back to a very early Universe. The Milky way is still to this day producing stars – it is known as a “cannibal” galaxy, which ate up smaller galaxies during its formation…again, all due to gravity. A larger mass will always attract a smaller mass with a force that is directly related to its large mass. The structure of the milky way to date is like this – old stars exist in the galactic “halo” – a sphere of stars around the disc. The disc contains young stars and the Milky Way has a spiral shape due to the galaxy spinning as it formed. There are plenty of other galaxies out there though, we are just one of billions!