Visit us. National Maritime Museum. Plan your visit. Top things to do. Shop gifts inspired by navigation Find in store at the National Maritime Museum, and online! Learn about navigation history and discover replica instruments Prints. Astronomy repeat pattern. A graphic pattern with globes, sundials, compass, books and microscopes.
Perfect for your room or your child's bedroom! Object number: T Buy Now. Draco and Ursa Minor. Plate 1. A set of thirty-two constellation cards entitled 'Urania's Mirror', with a chart of the heavens for the latitude of London by Jehoshaphat Aspin , all contained within a box depicting Urania, the personification of Astronomy Greenwich Brass Sundial Compass. Our brass pocket sundial is a completely self-contained portable instrument, with a compass for alignment.
The gnomon is set for latitudes around 50 degrees North, so will be most accurate in the south of England, northern Europe, Canada and so on Visit Us.
A magnet is what makes a compass point north — the small magnetic pin in a compass is suspended so that it can spin freely inside its casing and respond to our planet's magnetism. A compass needle aligns itself and points toward the top of Earth 's magnetic field, giving explorers and lost souls a consistent sense of direction.
Related: How do compasses tell which way is north at the South Pole? A compass points north because all magnets have two poles , a north pole and a south pole, and the north pole of one magnet is attracted to the south pole of another magnet.
You may have seen this demonstrated by a pair of simple bar magnets or refrigerator magnets pushed end to end. The Earth is a magnet that can interact with other magnets in this way, so the north end of a compass magnet is drawn to align with the Earth's magnetic field.
A person standing on the equator is moving the fastest due to earth's rotation, while a person standing on a geographic pole does not move at all from earth's rotation. Earth's magnetic poles designate the central location of the region where the magnetic fields lines start and finish. Earth's geographic and magnetic poles are not exactly aligned because they arise from different mechanisms. Earth's magnetic field is caused by circulating currents of liquid iron in the outer core.
Furthermore, earth's magnetic poles are constantly changing location relative to earth's geographic poles. Currently, the magnetic south pole lies about ten degrees distant from the geographic north pole, and sits in the Arctic Ocean north of Alaska. The north end on a compass therefore currently points roughly towards Alaska and not exactly towards geographic north.
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