Download Learnerz IAS app from the Play Store now! Download



Hydrogen line UPSC NOTE


  • The hydrogen line is an important instrument in modern astronomy — from studying distant stars to looking for extraterrestrial intelligence (if it exists).

  • Each hydrogen atom is made of one proton and one electron. 

  • Both these particles have a property called spin

  • Colloquially, we can say the spin can point up or down at any given time. 

  • When the spins of both particles are pointing up (or down), they are said to be aligned

  • When they are pointing in opposite directions, they are anti-aligned.

  • When the spins are anti-aligned, the atom will have more energy than if they are aligned

  • The atom will shed this ‘excess’ energy when the electron flips its spin, emitting electromagnetic radiation of wavelength 21 cm.

  • In some detectors, this emission shows as a characteristic line, thus the name ‘hydrogen line’.

  • Scientists discovered this emission in 1951 and it transformed radio astronomy. 

  • By looking for this emission, they could detect clouds of cold, neutral hydrogen atomic gas in interstellar space

  • Soon after, they were able to create a map of the Milky Way galaxy for the first time, and discover its spiral arms.

  • Today, astronomers are also using the 21 cm as a probe to spot the first light emitted by the universe’s earliest galaxies

  • Because the emission doesn’t require complicated technologies to spot, astronomers also think it can be used to send information across space that, some day, an alien civilisation might detect



Amritsar,1,April 2024,301,Art & Culture,1,August 2023,251,Courses,7,Daily Current Affairs,48,December 2023,189,Disaster Management,2,Environment and Ecology,148,February 2024,228,Foundation Course,1,GDP,1,GEMS Club,1,GEMS Plus,1,Geography,154,Govt Schemes,2,GS 2,1,GS1,6,GS2,36,GS3,15,GST,1,History,9,Home,3,IAS Booklist,1,Important News,71,Indian Economy,118,Indian History,2,Indian Polity,135,International Organisation,12,International Relations,97,Invasive Plant,1,January 2024,240,July 2023,281,June 2022,6,June 2023,268,June 2024,173,March 2024,238,May 2022,17,May 2024,330,Mentorship,2,November 2023,169,October 2023,203,Places in News,2,Science & Technology,66,Science and Technology,90,September 2023,205,UPSC CSE,111,
Learnerz IAS | Concept oriented UPSC Classes in Malayalam: Hydrogen line UPSC NOTE
Hydrogen line UPSC NOTE
Learnerz IAS | Concept oriented UPSC Classes in Malayalam
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS PREMIUM CONTENT IS LOCKED STEP 1: Share to a social network STEP 2: Click the link on your social network Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy Table of Content