30-Second Astronomy

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

François Fressin

• Publisher: Icon Books
• Year: 2013
• eBook ISBN: 9781848316140
• Topic: Physical Sciences
• Subtopic: Astronomy & Astrophysics

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.

THE UNIVERSE

THE UNIVERSE

GLOSSARY

Big Bang The starting point of space and time in an explosion from a single, extremely hot and extremely dense point. According to various competing theories, the Universe whose expansion began with the Big Bang will end in the Big Chill, the Big Crunch or the Big Rip.

Big Chill Also known as ‘the Big Freeze’, one projected end for the expanding Universe, in which galaxies will drift away from one another, stars will burn out, galaxies will become exhausted, and the Universe itself will become vastly large, dark, and cold.

Big Crunch A second hypothesis for the end of the Universe, in which the Universe will expand until it reaches a critical point, then begin to contract, becoming more dense and hotter and finally reaching an infinitely dense, infinitely hot point called the Big Crunch. The Big Crunch could be the launching point for another Big Bang. The discovery of dark energy (a mysterious force fuelling the Universe’s expansion) has made this scenario outmoded.

Big Rip A third hypothesis concerning the end of the Universe, in which matter (at all scales from galaxies to subatomic particles) will be torn apart by the dark energy that pushes the expansion of the universe.

Cosmic Microwave Background A diffuse field of radiation – the first light released in the aftermath of the Big Bang that spread out through the expanding universe. The discovery of the Cosmic Microwave Radiation in 1964 established the primacy of the Big Bang over other theories of the origin and state of the Universe.

cosmology The study of the birth, shape, growth, size and projected end of the Universe.

dark energy Energy that fuels the expansion of the Universe.

dark matter Unseen matter whose gravitational effects are detected on visible matter, galaxies, and large-scale structures in the Universe.

fundamental forces The four basic forces effective in the Universe: the gravitational force, the electromagnetic force, the strong nuclear force and the weak nuclear force.

Hubble Constant The rate of expansion of the Universe.

hypernova Extremely powerful explosion – releasing substantially more energy than a supernova – that gives issue to gamma ray bursts of long duration.

inflation Intensely short, very fast expansion that occurred in the aftermath of the Big Bang. It was followed by a period of relatively gradual expansion. Inflation is thought to have occurred for just an infinitesimally small fraction of a second, between 10-³⁸ and 10-³⁶ seconds after the Big Bang.

light-year The distance that light travels in one year: 9.5 trillion kilometres (9.5 trillion miles).

MOND Modified Newtonian dynamics, a theory suggesting that the effects of gravity may be longer-lasting and stronger than generally thought, and that these effects rather than dark matter hold together galaxies and other clusters that would otherwise fall apart.

quasars Quasi-stellar radio sources. Astronomers first thought these were radio stars, but then discovered that the radio waves were emitted by a galaxy with a bright nucleus consisting of a supermassive black hole.

radio stars Stars that emit radio waves, such as pulsars.

steady-state theory Proposal first put forward by British physicist James Jeans in around 1920 and developed in 1948 by British astronomer Fred Hoyle and colleagues to counter the rival Big Bang theory of the origins and state of the Universe. According to the steady-state theory, new matter is being continuously created in a constantly expanding Universe, forming new stars and galaxies, while old galaxies and stars become unobservable as the Universe expands. The steady-state universe has a constant average density and no end or beginning in time. This theory has been discredited.

THE BIG BANG

the 30-second astronomy

An obvious consequence of the discovery that space is expanding is that there must have been a beginning to the Universe. All matter, space and time came into being at a unique starting point that we call the Big Bang. This idea was proposed initially by Georges Lemaître as a possible solution to Albert Einstein’s equations of General Relativity; it gained universal acceptance with the discovery of the Cosmic Microwave Background in 1964. Subsequent observations of the way that the population of galaxies containing strong radio sources changed with time further supported the idea of an evolving Universe. Astronomers have no firm explanation of what triggered the Big Bang, as our current understanding of the laws of physics cannot describe such an extremely hot and dense phase of matter – let alone yield any description of what could have happened ‘before’ this event. Within a tiny fraction of a second, the Universe underwent a short period of inflation, resulting in an extraordinarily rapid increase in its size – leading to its subsequent continued expansion – and its contents cooling. The first elementary particles began to form, and the fundamental forces separated out to take on their current nature.

3-SECOND BANG

Everything in our Universe is thought to have originate...

Table of contents

• Cover
• Title
• Copyright
• Contents
• Foreword
• Introduction
• The Planets
• The Solar System
• The Stars
• The Milky Way
• The Universe
• Space & Time
• Other Worlds
• Appendices