Historical eventMay 201964

Discovery of cosmic microwave background radiation

Discovery of the cosmic microwave background radiation by Robert Woodrow Wilson and Arno Penzias.

Everything on May 20Original source

In context

When
Wednesday, May 20 196462 years ago
Category
Historical eventA dated happening — a battle, treaty, launch, discovery, disaster or decision — recorded on this calendar day.
Era
20th century · 1960s
Recorded from
Wikipedia “On this day” feed

At a glance

Dates: From 1964.

What happened

Discovery of the cosmic microwave background radiation by Robert Woodrow Wilson and Arno Penzias.

May 20 through the years

Other entries on the same calendar day, in order.

  1. 1964Discovery of cosmic microwave background radiation
  2. 1996Romer v. Evans
  3. 2002Timor-Leste
  4. 2009Indonesian Air Force
  5. 2011Mamata Banerjee
  6. 20122012 Northern Italy earthquakes
  7. 2013Enhanced Fujita scale
  8. 20132013 Moore tornado
  9. 2016Singapore
  10. 2019International System of Units
  11. 2022Russo-Ukrainian war

Also in 1964

  • March 14Jack RubyJack Ruby is convicted of killing Lee Harvey Oswald, the assassin who had shot and killed John F. Kennedy the previous year.
  • September 13South VietnamSouth Vietnamese generals Lâm Văn Phát and Dương Văn Đức staged a coup attempt after being demoted by junta leader Nguyễn Khánh.
  • September 13Army of the Republic of VietnamSouth Vietnamese Generals Lâm Văn Phát and Dương Văn Đức fail in a coup attempt against General Nguyễn Khánh.
  • September 13Martin Luther King Jr.Martin Luther King Jr. addresses a crowd of 20,000 West Berliners on Sunday, in Waldbühne.
  • September 18Wedding of Constantine II and Princess Anne-MarieThe wedding of King Constantine II of Greece and Princess Anne-Marie of Denmark took place in Athens.
  • September 5Hurricane CleoHurricane Cleo dissipated after causing 156 deaths, mainly in Haiti, and causing roughly US$187 million in damages across the Caribbean a…
  • October 22Ian FlemingThe first volume of Ian Fleming's children's novel Chitty-Chitty-Bang-Bang was published posthumously.
  • October 22Jean-Paul SartreJean-Paul Sartre is awarded the Nobel Prize in Literature, though he does not accept the prize.

Everything we record for 1964 →

Sources

Cite this page

“Discovery of cosmic microwave background radiation”, What's On This Date, https://whatsonthisdate.com/app/event/discovery-of-cosmic-microwave-background-radiation-1964-may-20, accessed October 28, 2026.

Cite the underlying source as well — the source links above go to the record this entry is adapted from.

Questions about this entry

When did Discovery of cosmic microwave background radiation happen?

May 20 1964 — 62 years ago, on a Wednesday.

Where does this text come from?

Wikipedia “On this day” feed. Summaries are short adaptations that link back to the source, not reprints.

How do I cite this page?

Use the ready-made citation near the sources at the bottom of the page, and follow the source link to cite the underlying record as well.

Text adapted from Wikipedia under CC BY-SA 4.0 and from Wikidata (CC0). Images come from Wikimedia Commons; credit and licence are shown with each image. Editorial entries are © What's On This Date. Sources & licensing · How this site works.