'Noon' means 'midday' or 12 o’clock during the day. ‘Midnight’ refers to 12 o’clock (or 0:00) during the night.

When using a 12-hour clock, 12 pm typically refers to noon and 12 am means midnight. While most people follow this convention, technically this isn’t quite right.

To avoid any confusion, 12 o’clock should be written as 12 noon or 12 midnight instead.

Alternatively, you could use the 24-hour clock system, where 12:00 is noon and 00:00 (or 24:00) is midnight.

What does am and pm mean?

The 12-hour clock divides the 24 hour day into two periods:

  • am - stands for the Latin ante meridiem, translating to "before midday", before the sun has crossed the meridian line.
  • pm - stands for post meridiem or "after midday", after the sun has crossed the meridian line.

At exactly 12 noon, the Sun is at its highest point in the sky and directly over the meridian. It is therefore neither 'ante' (am) nor 'post' (pm) meridiem. At 12 midnight it also neither am nor pm.

If all these questions about time have got you in a spin, why not visit the Royal Observatory, where many more mysteries of time await...