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30-Second Astronomy E-Book

François Fressin

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Herausgeber: Icon Books
Kategorie: Wissenschaft und neue Technologien
Serie: 30-Second
Sprache: Englisch

Beschreibung

How hot is Venus? Can you distinguish between a pulsar and a quasar? Is there a universe or a multiverse? Where do we fit into the infinitely grand scheme of things? How do we map the Cosmic Microwave Background? Most tantalizing of all: Is there anyone out there? The answers to these and many other far-out questions lie in your hands. Everyone's gazing at the heavens, but a voyage through the star-studded contents of this book will blow your mind. Astronomy encapsulates the terrifying hugeness of the cosmos into bite-size particles that mere earthlings can understand: 50 incredible discoveries brought down to Earth using no more than two pages, 300 words, and a picture. This one small volume takes you on a cosmic tour, shedding light on the most awesome of objects and places, explaining some very big ideas, concepts, and discoveries, and presenting the scientists and observers who have done so much to crack Life, the Universe, and Everything. Welcome aboard.

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Veröffentlichungsjahr: 2013

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Leseprobe

30-SECOND

ASTRONOMY

The 50 most mindblowing discoveries in astronomy, each explained in half a minute

Editor

François Fressin

Foreword by

Martin Rees

Contributors

Darren Baskill

Zachory K. Berta

Carolin Crawford

Andy Fabian

François Fressin

Paul Murdin

First published in the UK in 2013 by Icon Books Omnibus Business Centre 39–41 North Road London N7 9DP email: [email protected]

The editor and contributors have asserted their 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.

This book was conceived, designed and produced byIvy Press 210 High Street, Lewes, East Sussex BN7 2NS, UKwww.ivypress.co.uk

Creative Director Peter Bridgewater

Publisher Jason Hook

Editorial Director Caroline Earle

Art Director Michael Whitehead

Designer Ginny Zeal

Illustrator Ivan Hissey

Profiles Text Viv Croot

Glossaries Text Charles Phillips

Project Editor Stephanie Evans

ISBN: 978-1-84831-597-6

Colour origination by Ivy Press Reprographics

10 9 8 7 6 5 4 3 2 1

Foreword

Introduction

The Planets

GLOSSARY

Mercury

Venus

The Earth

The Moon

Mars

Jupiter

Profile: Galileo

Saturn

Uranus & Neptune

The Solar System

GLOSSARY

The Sun

The Solar Wind

Eris, Pluto & Dwarf Planets

Asteroids

Profile: Copernicus

Comets

Meteors

The Stars

GLOSSARY

Colour & Brightness of Stars

Binary Stars

Variable Stars

Giant Stars

White Dwarfs

Pulsars

Profile: Jocelyn Bell Burnell

Supernovae

Black Holes

The Milky Way

GLOSSARY

Constellations

Molecular Clouds & Nebulae

Messier Objects

The Milky Way

Profile: William Herschel

The Other Galaxies

Galactic Structures

The Universe

GLOSSARY

The Big Bang

The Expanding Universe

Profile: Edwin Hubble

Cosmic Microwave Background

Beyond Visible Light

Cosmic X-Rays

Gamma Ray Bursts

Quasars

Dark Matter

Dark Energy

Space & Time

GLOSSARY

Light-Years & Parsecs

Ellipses & Orbits

The Light Spectrum

Gravity

Relativity

Gravitational Lensing

Profile: Fritz Zwicky

Wormholes

Other Worlds

GLOSSARY

Extraterrestrials

Profile: Carl Sagan

Exoplanets

Hot Jupiters

Super-Earths & Ocean Planets

Towards Another Earth

Evidence for Other Life

APPENDICES

Resources

Notes on Contributors

Index

Acknowledgements

FOREWORD

Martin Rees

The night sky is the most universal part of our environment. Throughout history, people have gazed up at the same ‘vault of heaven’, though each culture has interpreted it in its own way. Ever since the Babylonians, patterns have been recorded in planetary motions. The need for a precise calendar, and for navigation across the oceans, has motivated advances in timekeeping, optics and mathematics. Indeed, astronomy has always been a driver for technology. And, thanks to huge telescopes, probes and advanced computers, modern astronomers have discovered the amazing cosmic panorama described in this book.

Theorists like myself lag far behind in trying to make sense of it all. But we have made progress. We can trace cosmic history back to a mysterious beginning nearly 14 billion years ago, when everything was squeezed hotter and denser than anything that can be created in a laboratory; we understand in outline how the first atoms, stars and galaxies emerged. We realize that our Sun is a typical star among the billions in our Galaxy; and that our Galaxy is just one of many billions visible through a large telescope. Moreover, some theorists speculate that a further ‘Copernican demotion’ may lie ahead: physical reality is almost certainly more extensive than the domain we can observe; indeed ‘our’ Big Bang could be just one of many.

But recent advances haven’t just extended our cosmic horizons: they have revealed richer detail. Probes to other planets of our solar system (and their moons) have beamed back images of varied and distinctive worlds. More important still, we’ve inferred, by detecting very slight changes in the motions and brightness of stars, that most of them are orbited by retinues of planets, just as the Earth and other familiar planets orbit the Sun. In coming years, we will be swamped by fascinating new data – perhaps even evidence of life around other stars.

Astronomy now attracts wider interest than ever before – its discoveries are part of modern culture. Moreover, the joy of discovery isn’t now limited to professionals — indeed they are swamped by the sheer quantity of data. So there is scope for ‘citizen scientists’, who can access and download data from surveys made with the world’s best telescopes, and perhaps discover a new galaxy or a new planet. And serious amateurs, using small telescopes with the latest instrumentation, can match what professionals with much larger telescopes could do 50 years ago.

Our brightest neighbour

Planet Venus is very visible, partly because sunlight is easily reflected by the sulphurous clouds that blanket its atmosphere. Venus is the closest planet to our Earth, within reach of questing space probes, although its hot, deadly atmosphere prohibits any human exploration of its surface.

The technical details of all modern science are arcane. However, I believe that the essence of any discovery can be conveyed in accessible language. To condense a concept into 30 seconds is a bigger challenge, but one that has been triumphantly met by the authors here.

This book deserves wide readership among those fascinated by the extraordinary ‘zoo’ of objects in the cosmos – a cosmos governed by physical laws that allowed creatures to evolve (on Earth and perhaps on alien worlds too) with minds able to ponder its wonder and its mystery.

INTRODUCTION

François Fressin

Almost every discovery about the Universe has led us to realize how insignificant the Earth is. Compared to the rest of the Universe, our Earth represents roughly as much as a drop of water in the oceans, or a grain of sand in the deserts. In almost every field of research, astronomers have been surprised both by the extent of astrophysical structures and by their diversity.

But astronomical discoveries also tell us how strongly we are connected with the cosmos. We learn about the solar system, and we appreciate the interplay of its constituent parts with the appearance of life on Earth and its evolution. Comets brought the vast quantity of water that formed our oceans. The Moon slowed the Earth’s rotation and is responsible for the tides and the seasons. Jupiter scattered asteroids that would otherwise dramatically impact on the Earth. Our connection to the stars is even stronger. The air we breathe, the iron in our blood, the carbon in our flesh; all of these came from the core of a dying star, billions of years ago.

Giant planets

Despite their size, the very existence of Uranus and Neptune was unknown to astronomers prior to the invention of the telescope.

Astronomy has this strange duality between insignificance and preciousness. A human life is so close to nothing in the immensity of space and the passage of ages. But nowhere and never has there existed someone exactly like you. If we define spirituality as an inner path enabling a person to discover the essence of his or her being, then astronomy is definitely a spiritual experience.

The topics in this book will give you an idea of this barely imaginable immensity and diversity. Unicorns, psychic powers, flying cities are fairly easy to picture. How about objects so massive that they distort space and time, a dark energy scattering the entire Universe apart? How about the fact that the breadth of your finger, held up to the sky, covers millions of galaxies, each one containing billions of stars like the Sun, or the fact that you are standing on a ball of mud that will endlessly fly through the void? Any one of those scenarios is a little tougher to imagine, but they all reflect the real world.

Scientists are often viewed as emotionally removed and logical people who prefer figuring out what’s behind the scenes, instead of simply contemplating the beauty of the world, or who attempt to unravel a mystery rather than consider it sacred, untouchable. I believe that comprehension of the natural world does not diminish its capacity to inspire emotional wonder.

30-Second Astronomy offers 50 great astronomical discoveries, each one summed up by recognized experts in different fields of astronomical research who accepted the challenge to try to encapsulate each topic in a way that is at once succinct, accessible and reflects the consensus of the current understanding of astrophysical phenomena.

Dramatic ending

Giant stars are far more luminous and have shorter lifespans than slower-burning dwarfs. The bigger the star, the shorter its life, which ends as a supernova explosion, leaving behind a neutron star or black hole.

The topics are grouped in seven sections, roughly organized according to their distance from Earth and the time of their discovery. The first is The Planets – those other worlds next door. The second describes the other bodies of The Solar System, comets and asteroids, in this small part of space where everything revolves around the Sun. Section three focuses on The Stars, especially the dramatic ending of their lives, sometimes resulting in supernovae explosions and the formation of pulsars or black holes. In The Milky Way lie explanations of the objects in the night sky, and how millions of stars organize into galaxies. Section five, The Universe, gathers the current knowledge of what we know of the beginning of time, of the Big Bang, and of the ancestors of stars and galaxies. Space & Time charts the principles that rule the motions of astrophysical objects, and how much we can learn by studying the light we receive from them. The final section, Other Worlds, leads us back to the beginning, humans on Earth observing the sky, wondering if there are other Earths like ours – and other life. It features the recent discovery of planets orbiting stars other than the Sun. Each section profiles a herald of research in each field, summarizing the lives of exceptional scientists like Edwin Hubble or Carl Sagan.

This book serves two purposes. Its structure and approach are such that you can dip into one entry and learn what a black hole really is, or what the Curiosity rover is looking for on Mars. Or, read it from the start and you will have an informed overview of the state of scientific knowledge of the Universe today. Just as we don’t truly know ourselves if we don’t connect with others, nor do we really know the country in which we dwell unless we have travelled and lived in another country, looking at other worlds and thinking about this Earth in the immensity of space may provide one small step towards awakening a consciousness of what inhabiting this world means.

THE PLANETS

GLOSSARY

Apollo programme US National Space and Aeronautic Association (NASA) initiative to land a man on the Moon, inaugurated in 1961 and comprising 17 missions in 1967–72. Apollo 11 made the first manned landing on the Moon’s surface on 20 July 1969; Apollo 17 was the programme’s final flight in December 1972. In the course of the programme there were six lunar landings in which 12 US astronauts walked on the Moon.

atmosphere Layer of gases surrounding a planet or any body of sufficient mass, including a star; the layer’s shape is maintained by gravity.

biomass Biological material that comes from living or recently living organisms.

core Central part of a planet or star.

crust The solid outer part of a planet or natural satellite.

gas giant A large planet that consists primarily of gases instead of rock. The four gas giants in our solar system are Jupiter, Saturn, Uranus and Neptune. There are other gas giants beyond the solar system, in orbit around other stars.

greenhouse effect Process through which heat radiated from a planet’s surface is absorbed and then radiated outwards in all directions (including back down towards the surface) by gases in the atmosphere. As a result, the temperature on the surface and beneath the atmospheric gases is raised. Earth has a greenhouse effect, but so do other planets, such as Venus; the greenhouse effect is far stronger on Venus than on Earth.

Low Earth Orbit An orbit of the Earth at an altitude of 145–1,000 kilometres (90–620 miles). All manned space flights, apart from those of the Apollo programme, all manned space stations and most artificial satellites are in the Low Earth Orbit.

mantle A layer about 2,900 kilometres (1,800 miles) thick, between the outer part of the Earth’s core and its surface (crust).

mare Areas of basaltic lava on the Moon’s surface. (Basalt is a grey-to-black igneous rock.) Early astronomers wrongly identified these as areas of water and they were named mare (Latin for ‘sea’ or ‘seas’). There are several such areas, including the Mare Nubium (‘Sea of Clouds’) and the Mare Serenitatis (‘Sea of Serenity’); together, they form approximately 16 per cent of the Moon’s surface. They appear as dark areas on the Moon, visible with the naked eye, and make up the patterns interpreted in some cultures as ‘the Man in the Moon’.

meteor Colloquially known as a ’shooting star’, the name given to a streak of light caused by rock or dust burning up as it falls through a planet’s atmosphere.

meteor shower The appearance of several meteors in short succession.

meteorite A meteoroid that has landed on the surface of a moon or planet.

meteoroid A rocky body, smaller than an asteroid, in our solar system.

moon Also known as a natural satellite, an astronomical body that orbits a planet (or smaller body), known as its ‘primary’. The Earth’s Moon is the fifth largest natural satellite in the solar system, after Ganymede (the largest, a moon of Jupiter); Titan (second largest, a moon of Saturn); and Callisto and Io (third and fourth largest, moons of Jupiter).

niche environments Settings specialized to suit a particular species.

outgassing The release of gas that was absorbed, frozen or otherwise trapped in a surface – for example, in an ocean or area of rock on the surface of a planet.

protoplanet The ‘embryos’ or initial formations of planets, formed in a protoplanetary disc (cloud of dust and gas surrounding a new star). They form from the collision of smaller planetesimals. Where there are several protoplanets in orbit around a star, they collide to form one or more planets.

regolith Any loose mixture, such as soil or pieces of stone, that covers solid rock, from Greek words meaning ‘blanket’ and ‘rock’. Found on the Earth, the Moon and on other planets, moons and asteroids.

ring system Also known as a ‘planetary ring’, a disc-shaped formation of dust and particles (up to several meters in size) orbiting a planet. The most celebrated ring system in our solar system is around Saturn; Neptune, Uranus and Jupiter also have planetary rings.

tectonic plates Movable pieces of a planet’s crust (outer surface) and parts of the upper mantle (the layer directly beneath the crust).

tenuous Lacking in density. Used of a planet’s atmosphere.

MERCURY

the 30-second astronomy

Mercury is the smallest of the eight planets, with a diameter of 3,032 miles (4,879 km). The closest planet to the Sun, it is the speediest in its orbit: Mercury orbits the Sun in 88 Earth days. It rotates relative to the stars once on its axis every 59 days, turning three times on its axis for every two orbits. Because of the way that the planet rotates relative to the Sun as it orbits, its calendar is bizarre: a single day on Mercury (from sunrise to sunrise) lasts two Mercurian years or 176 Earth days. Mercury has no seasons and the largest temperature range on any planet in our solar system – from 400°C (800°F) at noon on its equator to –200°C (–300°F) near its poles at night; the temperature is especially low in the perpetually shadowed bottoms of its polar craters, where there are accumulations of ice. Mercury has a cratered, solid surface, much like the Moon. Its atmosphere is tenuous (lacking in density) and consists of atoms trapped from the Sun or outgassed from its hot surface. Mercury’s craters were formed in the same way as the craters on the Moon, through bombardment by asteroids and meteors.

3-SECOND BANG

Named after the messenger of the ancient Roman gods, Mercury is a fast-moving planet of extremes – very hot by day and very cold by night.

3-MINUTE ORBIT

Mercury’s orbit is the most elliptical of any planet, as well as the closest to the Sun, so it experiences a large variation in gravitational pull. This makes its orbit a test bed for the theory of gravity. Its orbit does not quite fit Isaac Newton’s theory, but Albert Einstein’s theory of gravity, known as General Relativity, solved the anomaly – and this was the first proof that General Relativity was better than Newton’s theory.

VENUS

the 30-second astronomy

Venus is roughly the size of the Earth, with a diameter of 12,104 kilometres (7,521 miles). It orbits the Sun inside the Earth’s orbit, once every 224 days, and rotates every 243 days – backward. Like Earth, Venus has an atmosphere, but on Venus this is hot, dense and consists primarily of carbon dioxide, creating an intense greenhouse effect that passes on the Sun’s heat to the surface and traps it below the atmosphere. As a result, the temperature on Venus averages 480°C (890°F) – hot enough to melt zinc. Seen from outside, the atmosphere supports opaque clouds that completely obscure the surface; seen from below, the sky is sulphurous yellow, as imaged by space vehicles that have landed to record the environment. Venus has been mapped by cloud-piercing radar both from Earth and from a space satellite, Magellan (1990–94). The surface is completely dry, and made of scaly, black volcanic rocks. Venus has more than 100 volcanoes, with solidified rivers of lava on their sides. Most terrestrial volcanoes are due to upwelling magma penetrating the surface of a planet at the edges of colliding tectonic plates – Venus has no tectonic plates and its volcanoes are fed through weak surface spots.

3-SECOND BANG

In some respects Earth’s twin, the planet Venus has suffered global catastrophes that have made its surface hellish – hot, black rock beneath a sulphurous sky.

3-MINUTE ORBIT

Space vehicles sent to Venus must be strengthened to withstand the atmospheric pressure (about 90 times the pressure on Earth) and proofed against sulphuric acid rain falling from the clouds. They also have to withstand the searing heat. Landing craft that have survived the descent and landed on the rocks without falling over have operated only for an hour or so. The existence of Venusian extraterrestrials seems improbable.