When you look out to a beautiful pink-red sky this evening, you may utter the phrase "red sky at night, sailor's delight" - but why? 

People around the UK and the world frequently use the saying whenever a sunset lights up the sky. 

"Red sky in the morning" on the other hand is a "sailor's warning" - but is there any scientific meaning behind the phrases?

Here's what you need to know about what the sayings mean and where they originate from... 

Why do we say "red sky at night, sailor's delight"?

"Red sky at night, sailor's delight" is a common phrase, but you might also know it as "shepherd's delight", which is the original version. 

"Shepherd's delight" and "shepherd's warning" were first used in the Bible in the book of Matthew. 

The weather phrase was used to help shepherds in the hills prepare for the following day's weather conditions. 

And according to the Met office, there is actually some scientific proof behind the age-old saying - particularly in the UK where the weather system comes from the west.

Normally, when there is a red sky at night, it means that there is good weather coming. 

This is because a red sky at night generally signifies high pressure is travelling from the west, meaning the next day's weather will likely be dry and clear. 

Meanwhile, "red sky in the morning, shepherd's warning", is because the good weather has already passed through towards the east, in turn making it likely that we will face wind and rain from low pressure. 

Why do red skies appear at night?

A red sky occurs when dust and small particles get trapped in the atmosphere by high pressure.

This then scatters blue light leaving only red light, which gives the sky its notably different red coloured appearance.

Meanwhile for red sky in the morning, the same thing happens but this time it means that the high pressure is moving towards the east and low pressure is moving in from the west, often bringing bad weather.