Our Universe is huge. In each and every direction on the sky, powerful telescopes observe galaxies whose light took more than 10 billion years to arrive at Earth. But wait - if we receive such ancient light from two opposite directions, and if the Big Bang happened just' 13.8 billion years ago, does that mean that the Universe is expanding faster than light? And wouldn't that violate Albert Einstein's theory of relativity, which says that the speed of light is an absolute limit? The answer may surprise you. But first, we need to take a closer look at the expansion of the Universe.
As described in the previous instalment of this series, we know that the Universe is expanding because galaxies appear to speed away from each other - their mutual distances are continuously increasing. But we also saw that cosmic expansion shouldn't be pictured as galaxies racing through empty space at incredibly high velocities. Instead, it is empty space itself that expands, pushing the galaxies ever further away from each other.
Esta historia es de la edición February 2023 de BBC Sky at Night Magazine.
Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.
Ya eres suscriptor ? Conectar
Esta historia es de la edición February 2023 de BBC Sky at Night Magazine.
Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.
Ya eres suscriptor? Conectar
Could We Find Aliens by Looking for Their Solar Panels?- Designed to reflect ultraviolet and infrared, the panels have a unique fingerprint
Researchers searching for life beyond Earth spend a lot of time thinking about what telltale signs might be detectable astronomically. Forms of unambiguous evidence for the presence of life on another world are known as biosignatures. By extension, techno signatures are indicators of activity by intelligent, civilisation-building life.
Antimatter- In our continuing series, Govert Schilling looks at antimatter, the strange counterpart to most of the matter filling our Universe
Particles and corresponding antiparticles are very much alike, except they have opposite electrical charges. For instance, the antiparticle of the electron - known as the positron - has the same tiny mass, but while electrons carry a negative electrical charge, positrons are positively charged.
Where Have All The Milky Way's Early Stars Gone?- Our Galaxy has a curious lack of pristine stars
The Big Bang produced a Universe filled almost exclusively with hydrogen and helium; all other elements - what astronomers call metals - were produced by stars, supernovae and everything that happens later. So if you can pick out a pristine star with no metals polluting it from among the billions in the Milky Way, then you are likely to have a star dating from our Galaxy's earliest days.
Inside The Sky At Night - Two years ago, exoplanet scientist Hannah Wakeford received some of the first data from the JWST
Two years ago, exoplanet scientist Hannah Wakeford received some of the first data from the JWST. In July's Sky at Night, we discovered what she's learned since then.
How to stack DSLR data in Siril
Easily combine multiple frames to boost detailin your astro photos
Lunar occultation of Saturn
You'll need to strike a balance on 21 August to capture the Moon covering the ringed planet
How to plot a variable star light curve
A rewarding project to chart stars that change brightness
Smartphone photography with a telescope
Mary Mcintyre explains how to get impressive night-sky images using your phone
Once-a-century solar storm is overdue
If a Carrington Event struck today it would be catastrophic, says Minna Palmroth
The new era of human spaceflight
There's been a step-change in crewed space missions since the dawn of the 21st century. Ben Evans charts its course and looks ahead to future horizons
