International Space Agencies – Missions and Discoveries

SPT0418-47: The Baby Milky Way

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Galaxies, Milky Way

Mains level : Not Much

SPT0418-47, a golden halo glinting 12 billion light-years away is the farthest galaxy resembling our Milky Way was recently spotted by astronomers.

Try this PYQ:

Which of the statements about black holes in space is/are correct?  (CSP 2016)

  1. It is a region in space where the pulling force of gravity is so strong that light is not able to escape.
  2. It can result from the dying stars.

Select the correct answer using the code given below:

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

SPT0418-47

  • The galaxy, called SPT0418-47, is so far away that it took billions of years for its light to reach Earth and so our image of it is from deep in the past.
  • It was picked up by the powerful Alma radio telescope in Chile using a technique called gravitational lensing, where a nearby galaxy acts as a powerful magnifying glass.
  • This was when the Universe was 1.4 billion years old — just 10% of its current age — and galaxies were still forming.
  • It has features similar to our Milky Way — a rotating disc and a bulge, which is the high density of stars packed tightly around the galactic centre.

What makes it special?

  • This is the first time a bulge has been seen this early in the history of the Universe, making SPT0418-47 the most distant Milky Way look-alike.
  • Thus the infant star system challenges our understanding of the early years of the Universe.
  • Researchers expect these young star systems to be chaotic and without the distinct structures typical of mature galaxies like our Galaxy.
  • This unexpected discovery suggests the early Universe may not be as chaotic as once believed and raises many questions on how a well-ordered galaxy could have formed so soon after the Big Bang.

Back2Basics: Milky Way

  • The Milky Way is the galaxy that contains our Solar System, with the name describing the galaxy’s appearance from Earth.
  • It appears like a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye.
  • From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within.
  • Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610.
  • Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe.
  • Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies.
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