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)
- It is a region in space where the pulling force of gravity is so strong that light is not able to escape.
- 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
- 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.