Trivia

Hard

Atomic Time Is Kept Using Atoms Of What Type?

Einsteinium
Radium
Caesium
Uranium

Answer: Caesium

The exact definition of a second has undergone quite a few revisions over the centuries. The second was originally defined as the second division of the hour by 60 (the first division was the minute).

Loose time keeping well into the 19th century however meant that a second was fairly fluid if it was even measured at all. By 1892 scientists had finally hammered out a more precise definition: the fraction 1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.

That definition was refined for next seventy years or so until the  International Committee for Weights and Measures abandoned the idea of linking the scientific second to explicitly to length of the day. Instead the second would be defined via atomic clock, specifically: the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.

Although atomic clocks have been improved many fold since the 1960s, isotopes of the caesium atom have been keeping time for us ever since.

Trivia

Easy

A Deadly Wave Of What Swept Through Boston In 1919?

Trivia

Hard

The Comet Lovejoy Is Notable For Leaving A Trail Of?

Trivia

Hard

Cloudflare Uses Which Of These Items To Generate Random Cryptographic Data?

Trivia

Easy

The Screen Of Space Invaders Was Colored By What?

Trivia

Hard

The First Toy Advertised On Television Was?

Trivia

Hard

Which U.S. Coin Is The Most Cost Effective To Mint?

Trivia

Hard

The First Professional Baseball Team Was The?

Trivia

Very Hard

Which State Has The Highest Accuracy In Predicting Presidential Winners?

Trivia

Hard

What Was The First Electronic Programmable Computer?

Trivia

Hard

Which Sci-Film Was The First Nominated For A Best Picture Oscar?