Simply put, a compass is a tool that points out directions, such as North, South, East, and West. These are also known as the cardinal directions.
In more detail, it’s a magnetized metal that will turn towards the Earth’s magnetic north pole. The most common form is the pocket compass. It looks similar to a watch and will point out the Northern direction when held in your hand.
How does a compass work?
The Earth is a giant magnet with two centers of force; the North and South Poles. The core of the planet, mainly molten iron, creates a magnetic field as it spins around. This makes the north and south magnetic poles and how compasses work.
The needle in a compass is made of magnetized metal, usually iron, placed on a pivot or pin, and suspended in liquid (usually some mineral oil or white spirit) so it can freely turn. The compass needle can detect the Earth’s magnetic field and faces the Magnetic North when the held level is in your hand. The person using the device can then work out all the other directions.
Around the compass, you can also find little measurements. These are called degrees. The red end of the needle will always point North, and the white /black end will always mean south. On the outer case of the compass, there’s also usually an arrow at the top known as the ‘orientation arrow.’
What is a compass used for?
Maps were able to be created thanks to the compass. It even helped establish that the Earth is a globe, not flat.
The primary use for compasses was out at sea, as no landmarks could help with navigation. So instead, sailors used the stars, particularly Polaris, the North star, to help find their way. Though sometimes the sky could be cloudy or stormy, they couldn’t tell which way they were heading. This is why compasses are particularly important at sea.
Compasses today can be found in many modern appliances and are their own thing. YoIn addition, youan find them in smartphones, a
The History of the Compass
The earliest compass use recorded comes from the Chinese Han Dynasty and Tang Dynasty, around 200 BC. They discovered that some metal from the ground was naturally magnetic. They so could use these metals, known as lodestone, or magnetite, to magnetize iron needles in the first types of compass.
In non-European countries, magnets were used spiritually, such as for divination, geomancy, and, in particular, Feng Shui, to help maximize good fortune.
Very early compasses were made of the magnetized needle mounted on a piece of wood that floated in a dish of water. These were mainly used as backups when the sun or stars could not be seen in the sky. However, as more people learned how to use them and the understanding of magnetism grew, the tools became more popular and valuable.
In the 12th century, as early scientists discovered more about magnetism, the compass needle was placed on a pin, and in the 13th century added to the compass cards. At first, this compass card showed only the leading four cardinal directions, but over time this design evolved to offer 32 directional points.
By the 16th century, compasses and charts were commonly used by sailing ships.
What is a compass rose?
A compass rose is a figure found on maps, compasses, and nautical charts. It’s also known as a ‘windrose’ or ‘Rose of the Winds.’
During the 12th century, Europeans created the compass rose. It enabled the creation of the eight principal winds, which includes the four cardinal directions (North, South, East, and West) plus the new intercardinal directions; North-East, South-East, South-West, North-West.
These helped early sailors see where they were going during their sea voyages. You can also find compasses with roses with 16 or even 32 points. These include directions such as North-northwest, east-northeast, and south-southwest.
What is a compass bearing?
A bearing of a location is the number of degrees in the angle measured in a clockwise direction from the north line to the line. For example, the path of an object directly to the east would be 90 degrees.
Different types of compasses
There is a type of compass that always points to the True North as it uses the Earth’s rotation rather than its magnetic field. This is known as a gyroscope, and it was invented in 1906 by Hermann Anschütz-Kaempfe and is usually used by large ships and aircraft. It follows the Earth’s axis or rotation to find True North.
There’s also the solar compass. This version uses the shadow from the sun on the compass card to show direction. You can create one by placing a simple stick on the ground, placing stones around it, and using a string to follow the shadow. This helps to find the East and West cardinal directions.
Astrocompasses are aligned with fixed points in the sky, for example, stars. These are harder to use than the standard magnetic compass but are pretty helpful in polar regions where magnetic and gyrocompasses aren’t so reliable.
Nowadays, the GPS (Global Positioning System), which first began in the United States in 1973, is taking over from the traditional compass. GPS uses co-ordinates sent via satellites that are in orbit around the Earth. These signals are very accurate and reliable. Though many planes and ships still us advanced compasses for navigation.
Who could forget the compass that’s used in mathematics? A handy tool that helps with drawing circles and other geometric shapes and finding mid-points to help solve problems. Not related to Earth’s magnetic field, but still a compass worth mentioning.
Fun facts about compasses
- The magnetic and geographic poles are different. For example, the Earth’s Magnetic North Pole doesn’t align with the geographic North Pole, also known as the True North.
- True North always sits at the top of the Earth. Magnetic North is not a fixed point and changes over time in response to the changes in the Earth’s core. It’s thought that it is situated around 1000 miles away in Canada.
- The Magnetic North is said to have moved around 600 miles over time as the magnetic field has warped.
- The difference between the magnetic and true norths is called ‘Variation’ by pilots or mariners or ‘magnetic declination’ by land navigators.
- The Fleur-de-lis is often used to mark North on a compass. 1It is believed to have evolved from the original mark, a spearhead above the letter T, which stood for the Latin name for the North wind ‘Tramontana.’
- In Greenwich, London, in September 2019, True north and magnetic north were aligned for the first time in over 360 years.
