Finding your way in space Flashcards
navigate
use directions to go where you want to, often by using a map.
What’s up and what’s down for astronauts who are floating in zero gravity? In space is there a true north, like here on Earth? And how is everything complicated by the fact that all the stars and planets are moving?
True, but before mobile phones where invented arriving at your destination wasn’t so easy. At sea, sailors used the stars and Sun to navigate – to work out which direction they wanted to travel. And navigating on land was almost impossible without a compass – an instrument for finding directions that uses a magnetic needle which moves to always point north.
compass
instrument for finding directions that works using a magnetic needle that moves and always points north.
True, but before mobile phones where invented arriving at your destination wasn’t so easy. At sea, sailors used the stars and Sun to navigate – to work out which direction they wanted to travel. And navigating on land was almost impossible without a compass – an instrument for finding directions that uses a magnetic needle which moves to always point north.
magnetic pole
point near the North Pole or South Pole where the Earth’s magnetic field is concentrated.
Planet Earth is like a giant magnet. Because the needle of a compass is magnetised, it’s attracted to the magnetic pole – the points near the North and South Poles where the Earth’s magnetic field is concentrated.
…because Earth behaves like it has a giant bar magnet in it, and your compass needle will point north towards Earth’s magnetic pole. And we’ve arbitrarily defined north as, that’s what we’re going to say ‘up’ is, like, the North Pole – that’s as ‘up’ as you can go.
arbitrarily
arbitrary
decided randomly, not according to any particular reason or principle.
This explains how we find north, but Ethan points out that the decision to call north ‘up’ and south ‘down’ is arbitrary – decided by random chance, not based on any particular reason.
…because Earth behaves like it has a giant bar magnet in it, and your compass needle will point north towards Earth’s magnetic pole. And we’ve arbitrarily defined north as, that’s what we’re going to say ‘up’ is, like, the North Pole – that’s as ‘up’ as you can go.
When we look at a world map, we think of north as ‘up’, the USA in the northern hemisphere is above Brazil, in the southern hemisphere. But from space, Earth can just as easily be seen the other way up, with Australia, South Africa and South America at the top. Both views are equally true.
flip
turn over or move into a different position.
Well, the problem is that every few hundred light years the magnetic field flips - turns over or moves into a different position. So, a compass, which depends on magnetism, is no good for navigating in space.
So how do spacecraft know where they are, and which way to go? The answer is both simple and very clever – they use specialised heat sensors to detect the position of the Sun and use that to guide their way. So simple yet so ingenious! I’m sure it would have impressed the first person in space, whoever they were.
light year
unit measuring the distance that light travels in one year (around 6 trillion miles).
A light year sounds like a measurement of time, but in fact it measures the distance that light travels in one year – which, given that light can travel 7.5 times around the Earth in one second, is a very, very long way - around 6 trillion miles, in fact.
The problem with navigating in space is that the magnetic field flips irregularly every few hundred, or few thousand light years. There’s no central object like the black hole at the centre of our galaxy – it doesn’t dominate the whole galaxy, it doesn’t make a magnetic field that you can feel out here 25, 27-thousand light years from the centre. So, magnetism is not a good guide to navigating in space.
