How Many Moons Does the Earth Have? E-Book

Brian Clegg

• Herausgeber: Icon Books
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch
• Veröffentlichungsjahr: 2015

Seitenzahl: 188

Beschreibung

Why did Uuq become Fl? Why is the sky blue? Why is the sky black? What is spaghettification? There's a problem with the typical quiz. It always features far too much sport, 1980s pop and celebrity gossip – and not nearly enough science. How Many Moons Does the Earth Have?? is the ultimate solution. Test your knowledge to the limit with a sizzling collection of brain-stretching, science-based questions in two eight-round quizzes. Turn the page to get the answer immediately – and as each answer page explores the subject in more depth, this the only quiz that's just as entertaining to read from beginning to end as it is to play competitively. Where was the Big Bang? What links the elephant Tusko and Timothy Leary? What is the significance of 6EQUJ5? Science explainer extraordinaire Brian Clegg tells all…

Leseprobe

HOWMANY MOONS DOES THEEARTH HAVE?

Also by Brian Clegg

Dice World

Inflight Science

Introducing Infinity: A Graphic Guide

Light Years

Science for Life

The Quantum Age

The Universe Inside You

HOWMANY MOONS DOES THEEARTH HAVE?

THE ULTIMATE SCIENCE QUIZ BOOK

BRIAN CLEGG

Published in the UK in 2015 by

Icon Books Ltd, Omnibus Business Centre,

39–41 North Road, London N7 9DP

email: [email protected]

www.iconbooks.com

Sold in the UK, Europe and Asia

by Faber & Faber Ltd, Bloomsbury House,

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London WC1B 3DA or their agents

Distributed in the UK, Europe and Asia

by TBS Ltd, TBS Distribution Centre, Colchester Road,

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Distributed in the USA by

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Distributed in Australia and New Zealand

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Distributed in South Africa by

Jonathan Ball, Office B4, The District,

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ISBN: 978-184831-928-8

Text copyright © 2015 Brian Clegg

The author has asserted his moral rights.

No part of this book may be reproduced in any form, or by any means, without prior permission in writing from the publisher.

Typeset in PMN Caecilia by Marie Doherty

Printed and bound in the UK by Clays Ltd, St Ives plc

For Gillian, Rebecca and Chelsea

ABOUT THE AUTHOR

Science writer Brian Clegg studied physics at Cambridge University and specialises in making the strangest aspects of the universe – from infinity to time travel and quantum theory – accessible to the general reader. He is editor of www.popularscience.co.uk and a Fellow of the Royal Society of Arts. His previous books include Science for Life, Light Years, Inflight Science, Build Your Own Time Machine, The Universe Inside You, Dice World, The Quantum Age and Introducing Infinity: A Graphic Guide.

www.brianclegg.net

ACKNOWLEDGEMENTS

With many thanks to my editor Duncan Heath, and everyone at the excellent Icon Books for their support. Most of all, for every pub quiz I’ve ever taken part in and thought ‘I wish there was more science’.

CONTENTS

About the author

Acknowledgements

Introduction

Quiz 1, Round 1: Earth and Moon

Q1. Counting moons

Q2. Space Station blues

Q3. A question of dropping

Q4. The black hole of Earth

Q5. The man who fell through Earth

Q6. Lunar currency

Q7. Measuring the world

Q8. Eggs in space

Quiz 1, Round 2: Miscellany

Q1. Spaghetti science

Q2. Winning physics gold

Q3. The Carrington question

Q4. An absolute temperature

Q5. The movie snack menace

Q6. A distinguished ology

Q7. Elephant extraordinary

Q8. It’s Santa time

Quiz 1, Round 3: Mathematics

Q1. Pick an answer, any answer

Q2. The football player’s nightmare

Q3. An average kind of question

Q4. A random percentage

Q5. Robert Recorde’s claim to fame

Q6. Irrationally diagonal

Q7. Seven-league science

Q8. Coasting along

Quiz 1, Round 4: Biology

Q1. Eye spy

Q2. Locked up in a cell

Q3. Blood-red poser

Q4. Avian altitude

Q5. Hairy problem

Q6. Lousy ancestry

Q7. A rare question

Q8. Arachnid anxiety

Quiz 1, Round 5: Technology

Q1. The wind-up king

Q2. Conscious computing

Q3. A light-bulb moment

Q4. The Big Blue blues

Q5. Atomic company

Q6. Fizzing with ideas

Q7. Patent madness

Q8. Matrix mechanics

Quiz 1, Round 6: Chemistry

Q1. Molecular mindgames

Q2. It’s a gas

Q3. Bonding rituals

Q4. Helping the medicine go down

Q5. Water, water everywhere

Q6. Popping pills

Q7. She sells sea salt on the seashore

Q8. E is for blueberry

Quiz 1, First Special Round: Famous Scientists

Quiz 1, Second Special Round: Cryptic Science

Quiz 2, Round 1: Physics

Q1. Isaac’s apples

Q2. Time flies

Q3. Somewhere inside the rainbow

Q4. The electronic professor

Q5. Beam me up

Q6. Balletic bullet ballistics

Q7. Moonshine power

Q8. Gamow’s game

Quiz 2, Round 2: Biology

Q1. Tasty teaser

Q2. Our mousy cousins

Q3. Can a ground lion change its spots?

Q4. Making sense

Q5. Daily decay

Q6. Taste-tingling tangs

Q7. Dolly mixture

Q8. Mouse menace

Quiz 2, Round 3: The Mix

Q1. Train drain

Q2. Light fantastic

Q3. Alphanumeric enigma

Q4. Bovril bonanza

Q5. The Wardenclyffe wonder

Q6. Unpronounceable

Q7. Hazardous hydration

Q8. Hothouse habitat

Quiz 2, Round 4: History

Q1. Birth of Bacon

Q2. Albert’s alma mater

Q3. Cloud conundrum

Q4. Passing the baton

Q5. Saucer of secrets

Q6. Blue heaven

Q7. Ray gun remembered

Q8. Find the link

Quiz 2, Round 5: Space

Q1. Travelling light

Q2. Seeing stars

Q3. Universal knowledge

Q4. Ill-met by moonlight

Q5. Weighing up the solar system

Q6. Fast folk

Q7. Venusian values

Q8. A singular singularity

Quiz 2, Round 6: Technology

Q1. Charge your weapons

Q2. Wizard words

Q3. Spot the bot

Q4. Casting light on lifeguards

Q5. Computer composition

Q6. Focusing on lenses

Q7. Digital dreams

Q8. K is for kilo, kitchen and klystron

Quiz 2, First Special Round: Periodic Table

Quiz 2, Second Special Round: NASA

Further reading

INTRODUCTION

How Many Moons Does the Earth Have? has a traditional quiz format. The book contains two quizzes, each with six rounds of eight questions, plus two ‘special rounds’ which earn up to ten points and involve themed questions.

Sometimes, though, the best way to enjoy a quiz is to test yourself, so the book is designed to be read through solo as well. Each answer is accompanied by illuminating information, so there is more to it than just getting the answer right. Of course, if you’re using the book as a pub quiz, you don’t need to include these parts.

If you are going to use the book in a quiz, you’ll need to copy the questions from the two special rounds and print out enough so that each team can have their own question sheet. You might like to use one of these as a ‘table’ round, which is left on the teams’ tables to answer between the other rounds.

A popular addition in quiz play is to allow each team to have a joker to use on a round of their choice (before they see the questions), which doubles their points in that round.

The little factoids after each question are primarily for your enjoyment, but depending on your audience, it might add to the fun to read them out when running a quiz. And if a topic takes your interest, each question has a ‘Further reading’ link to the book list at the back, to really delve into a subject.

However you use the book – enjoy it!

QUIZ 1

ROUND 1: EARTH AND MOON

QUESTION 1

Counting moons

How many moons does the Earth have?

Answer overleaf

While you’re thinking …

Jupiter has at least 67 moons.

The largest moon in the solar system is Jupiter’s moon Ganymede, which has a radius of around 2,600 kilometres, more than one third the size of the Earth.

There is evidence already of moons around planets in other solar systems.

The Earth has one moon

This may seem an obvious answer to a ridiculously easy question, but viewers of TV show QI have been told that it isn’t true. While the show has been on air, the number they have provided has varied from 0 to 18,000 – but in reality, the obvious answer, 1, is the best.

The reason given for a large number is that lots of little lumps of rock get captured by Earth’s gravitational field for a few days and while captured are natural satellites, making them moons. The zero figure suggests that the Moon is a planet, not a moon, because it is unusually large compared with the Earth – but this decision is arbitrary and is not accepted by the astronomical community. (And as ‘the Moon’ it is just a moon.)

There is not as definitive a definition of ‘moon’ as there is of ‘planet’, but there are still clearly intended consequences from using the word ‘moon’. These are that the body in question should be:

Long-lasting – I suggest staying in orbit for at least 1,000 yearsSizeable – say at least 5 kilometres across

This would still allow moon status for the pretty dubious companions of Mars, Phobos and Deimos, which are about 20 kilometres and 10 kilometres across.

Clearly such rules are implied when we talk about moons. If the time rule didn’t exist, then every meteor that spent a few seconds passing through our atmosphere would be a moon, while without the size rule, we would have to count every tiny piece of debris in Saturn’s rings as a moon – each is, after all, a natural satellite.

Further reading: Near-Earth Objects

QUESTION 2

Space Station blues

We’ve all seen astronauts floating around pretty much weightless on the International Space Station. What percentage of Earth normal is the gravity at the altitude of the ISS?

Answer overleaf

While you’re thinking …

The first part of the International Space Station was launched in 1998.

The orbit of the ISS varies between 330km and 435km above the Earth – call it 350km for this exercise.

One of the favourite sections of the ISS for astronaut photographs is the Cupola, an observatory module that has been likened to looking out of the Millennium Falcon in Star Wars.

At the ISS, gravity is around 90 per cent Earth normal

Allow yourself a mark for anything between 88 and 92 per cent. Newton gives us a value for the gravitational attraction (F) between two bodies as: F=Gm1m2/r2.

We can use this to work out the difference between the ground and the ISS. Luckily, practically everything cancels out. G (gravitational constant) is the same, m1 (the mass of the Earth) is the same and m2 (the mass of a person) is the same. So the ratio of the gravitational forces ForceISS/ForceEarth is just r2Earth/r2ISS, where rEarth is the distance from the Earth’s centre to its surface and rISS the distance from the Earth’s centre to the ISS.

We’re saying the ISS is 350 kilometres up. And the radius of the Earth is around 6,370 kilometres. That makes rISS equal to rEarth+350, or 6,720 kilometres. Not very different. So the ratio of the forces is (6,370 × 6,370)/(6,720 × 6,720) – which works out around 0.9. To be more precise, the force of gravity at 350km is 89.85 per cent of that on the Earth’s surface.

So how come the astronauts float around, pretty much weightless? Because the ISS is free-falling under the force of gravity – which means it cancels out the gravitational pull. It might seem something of a headline news event that the Space Station is falling towards the Earth, but there’s another part to the story. The ISS is also travelling sideways. So it keeps missing.

That’s what an orbit is. The object falls towards Earth under the pull of gravity. But at the same time it is moving sideways at just the right speed to keep missing the Earth and stay at the same height. As a result every orbit has a specific velocity that a satellite needs to travel at to remain stable.

Further reading: Gravity

QUESTION 3

A question of dropping

Who dropped a hammer and a feather on the Moon to demonstrate that without air they fall at the same rate? (For a bonus – which mission was it?)

Answer overleaf

While you’re thinking …

It is very unlikely that Galileo dropped balls of different weights off the Leaning Tower of Pisa to show they fall at the same rate. The story came from his assistant, shortly before Galileo’s death. Galileo was a great self-publicist and would surely have mentioned it had it been true.

What Galileo did do, though, was compare the rate of fall of pendulum bobs and balls of different weights rolling down an inclined plane – much easier than getting the timing right with the Leaning Tower.

The Ancient Greeks thought that heavier objects fall faster because they have more matter in them, and matter has a natural tendency to want to be in the centre of the universe. So with more matter, a heavy object should have more urgency in its attempt to reach its preferred place.

David R. Scott dropped a hammer and feather on the Moon

I will let you off the middle initial – and have a bonus point if you knew that the mission was Apollo 15. Scott beautifully demonstrated that the only reason a feather falls more slowly on the Earth is because of the resistance of the atmosphere. (You can see him in action here: http://youtu.be/KDp1tiUsZw8)

The Ancient Greeks were perfectly capable of trying this out (not the hammer and the feather on the Moon, but dropping similar sized balls of different weights), but it didn’t fit with their approach to science, which was all about logical argument rather than observation and experiment.

Although Galileo did plenty of experiments, which mostly confirmed that different weights fall at the same speed, he also found a logical argument that would have worked for the Greeks if they had thought of it, and that would have enabled a much earlier development of an understanding of gravity.

Galileo imagined you had two balls of different weights, and the heavier did fall faster than the lighter one. You would equally expect a third ball of the combined weight of the two to fall faster still. But let’s make that third ball from two separate parts, one for each of the two original weights, joined by a piece of string. The heavier of the two should fall a bit more slowly than it would otherwise, because the lighter weight would slow it down. Similarly the lighter weight should fall a bit faster than it otherwise would. So, the connected weights should fall at an intermediate speed.

But that means the same weight, depending on whether or not it is split, has two totally different speeds – showing that the idea doesn’t make sense.

Further reading: Gravity

QUESTION 4

The black hole of Earth

If the Earth were made into a black hole, what would be the diameter of its event horizon?

Answer overleaf

While you’re thinking …

It’s often said that American physicist John Wheeler was the first to use the term ‘black hole’ in 1967, but it was casually in use at an American Association for the Advancement of Science meeting in January 1964, as a result of which it first appeared in print in a Science News Letter article by Ann Ewing. No one is sure who thought of it.

A black hole is a body that has been so compressed that gravitational attraction overcomes any opposing forces and it disappears to a point.

Although a black hole is a point with no dimensions, to the outside world it appears as a sphere known as the event horizon. This is the distance from the centre at which spacetime is so warped that nothing, not even light, can escape.

The event horizon of a black hole Earth would be 20mm

Allow yourself a point for anything between 15mm and 25mm and half a point for between 5mm and 50mm. The only known natural mechanism for black hole formation is when a dying star collapses, but in principle any chunk of matter could be converted into a black hole if it were sufficiently compressed, including the Earth.

Despite the Hollywood portrayal, a black hole is not a giant suction device that pulls in everything around it. Its gravitational attraction is just the same as that of the body that formed it – in the case of our hypothetical black hole, it would be the same as the Earth. But Newton made it clear that a gravitational body like the Earth acts as if all its mass were concentrated at its centre. The big difference between black hole Earth and the real thing is that you can get much closer to that centre of mass in the black hole version.

Since Newton’s time we have known that gravitational force follows an inverse square law – it increases as the square of the distance between the centres of mass of the attracting bodies decreases. So, when the distance halves, the force quadruples. The radius of the Earth is around 6,370 kilometres, so by going from our usual position on the Earth’s surface to that of the black hole’s event horizon means that the distance has reduced by a factor of 637,000,000. Which results in the force going up by a factor of 405,769,000,000,000,000. That’s a whole lot of gravitational attraction.

Further reading: Gravity

QUESTION 5

The man who fell through Earth

If you fell down an airless, frictionless hole going all the way through the Earth, how long would it take to fall to the other side? (To the nearest minute.)

Answer overleaf

While you’re thinking …

The diameter of the Earth is approximately 12,470 kilometres.

Your maximum speed falling through the centre of the Earth would be around 7,900 metres per second.

When you arrived on the other side of the Earth you would have to be removed quickly, to avoid falling back through again.

It would take 42 minutes to fall through the Earth

Score one point for anything between 41 and 43 minutes. (Half a point between 37 and 47 minutes.) The calculation, which uses calculus to pull together the timing as the person accelerates towards the centre of the Earth and then decelerates on the way out, assumes, of course, that there is no air resistance or friction as you travel, so you would have to build an evacuated tunnel through the Earth to make this impressive free journey possible.

Building a tunnel through the centre of the Earth would be a major engineering challenge. Not only would you have to build a tunnel 100 times longer than anything now existing, you would have to cope with high temperatures, radioactivity, and protecting your passengers so that they can survive the journey. You would also have to suppress any resultant escape of molten materials and a general tendency to cause earthquakes and volcanic disruption that would not make you popular with those living near the tunnel.

Dropping through the tunnel, you would accelerate as you travelled, influenced by a gradually decreasing gravitational pull. Then at the centre, after a moment of zero gravity, you would start to slow down, coming to a stop just as you reached the far side.

Interestingly, the journey time of 42 minutes is not dependent on taking your tunnel through the centre of the Earth. If you go to one side, and so make a shorter tunnel, the acceleration will reduce accordingly, and the journey will still take 42 minutes. As long as you can make the tunnel airless and frictionless, the process should work.

Further reading: Gravity

QUESTION 6

Lunar currency

What sized coin, held at arm’s length, would appear about the same size as the Moon?

Answer overleaf

While you’re thinking …

One of the smallest coins minted in the UK is the silver Maundy penny, donated to pensioners by the monarch at the Maundy Ceremony – it is just 11mm across.

The biggest UK coin that might still fall within living memory was the so-called ‘cartwheel’ penny, issued from 1797. It was a massive 36mm across, but was no match for the much rarer cartwheel two-penny piece at 41mm.

It is a pure coincidence that the Moon appears to be about the same size as the Sun. The Sun is approximately 400 times further away, but also around 400 times bigger.

No coin held at arm’s length is small enough to match the Moon

There isn’t a coin small enough – and there never has been. Remarkably, the Moon’s apparent size is only about the same as the hole produced by a hole punch (around 5 millimetres), held at arm’s length. You can test this out by holding a punched piece of card up to a full Moon – the whole thing is pretty much visible.

Why, then, does the Moon look so much bigger? It appears to be a psychological effect. Because the Moon is very bright in contrast to the dark night sky, our brains assume that it is bigger than it really is. The picture we see of the world is not like a photograph, which captures the relative placement of everything geometrically. Instead, the brain has a range of modules that handle aspects like shapes, shading, lines and so forth. The picture we ‘see’ is a construct rather than an actual photographic image. And this means that things really aren’t always the way we see them. This is why good optical illusions are so convincing.

In the case of the Moon, it can seem even bigger when it is low in the sky, appearing relatively enormous when apparently near to buildings or trees. Again, the brain is misjudging the situation. Because this effect is subjective, we can’t be certain that the Moon looks the same to other people as it does to us. And the lack of this effect is why photographs of the Moon taken with an ordinary camera look so disappointing. It takes a good telephoto lens to get the kind of big Moon our brains tell us is out there.

Further reading: Inflight Science

QUESTION 7

Measuring the world

What’s the distance from the North Pole to the equator through Paris to the nearest kilometre?

Answer overleaf

While you’re thinking …

The Greek philosopher Eratosthenes was the first person known to make a scientific measurement of the circumference of the Earth, by measuring the Sun’s position at noon in two well-separated locations and throwing in a spot of geometry.

The modern SI (Système International) unit metric system was established in 1960. The standard unit of length is the metre.

The US Congress ratified the use of metric units in 1866, and the conventional units used there, like the foot or pound, are defined from metric measures – but despite attempts to introduce it, the metric system has never been accepted by the American population.

It’s 10,000 kilometres from the North Pole to Paris

One point for the exact value, half a point for 100 kilometres either way. This bizarrely accurate measurement reflects the definition of the metre in 1795 as 1/10,000,000th of the distance from the pole to the equator through Paris. This distance was used to set up a platinum metre bar in 1799. Variants on this were used through to 1960, when the standard was moved to a definition based on wavelengths of light. In 1983 it became 1/299,792,458th of the distance light travels in a second.