Hard Science Fiction

Sep 9 2020

More rogue planets than stars in the Milky Way?

When stars are born, their surroundings are not for the weak or squeamish. Planets have to find their way through a young system that has not yet reached a steady state. If they are unlucky, they will be swallowed up by larger planets – or flung out of the system entirely. Then they become lonely wanderers traversing the universe as ice-cold, rocky hunks that are very difficult to detect. Nobody knows how many of these so-called “rogue planets” there are, because normal telescopes cannot detect their extremely low energy signatures. And they also can’t be discovered by means of…

Mars

Aug 24 2020

When the sky glows green on Mars

After the Sun sets on the Red Planet and temperatures fall below -62 degrees Celsius, part of its atmosphere begins to glow. It starts at an altitude of about 70 kilometers shortly after sunset. The spots, which are up to 1000 kilometers large and shine as brightly as the Northern Lights on Earth, then move at about 300 kilometers per hour across the night sky. Future astronauts, however, won’t be able to marvel at them, unfortunately, because the spectacle plays out only in the ultraviolet range, which is invisible to the human eye. Researchers chose a green color for…

Space

Aug 11 2020

The last of its kind?

Stellar streams consist of groups of stars moving in orbit together. They are usually remnants of small galaxies that were absorbed by larger galaxies or former star clusters. The Phoenix stream discovered four years ago is the latter. It was, as researchers show in an article in Nature, once a globular cluster, and a very special one at that. Globular clusters are special objects in themselves. Imagine the night sky full of gleaming stars shining much brighter than the brightest planets in our Solar System. The average distance between two stars of a globular cluster is only 0.1 light-years,…

Time travel in the quantum world: how to generate a self-healing reality

Astrophysics

Aug 10 2020

Time travel in the quantum world: how to generate a self-healing reality

The “butterfly effect” is a term from nonlinear dynamics, which is a subdomain of physics. It occurs in systems that meet three requirements: the output is not always proportional to the input (“nonlinear”), the progression is dependent on time, but is a function of only the original state (“dynamic”), and randomness is not a factor (“deterministic”: if A, then B). When these three conditions are met, a small change to the initial conditions can lead to large changes in the results. The phrase was coined by the meteorologist Edward Lorenz, who was referring to a butterfly flapping its wings…

How many planets fit into a star’s habitable zone?

Life

Aug 9 2020

How many planets fit into a star’s habitable zone?

The habitable zone of our Solar System is relatively narrow. Mars is at the very outer edge of it, while Venus, which orbits closer to the Sun than Earth, is not quite inside it. Of eight planets, only the Earth is at just the right distance from its host star. A ratio like this would naturally lower the chances of finding inhabitable worlds in the universe. But is the Solar System an exception or the rule? Astronomers have, in fact, found other star systems that give a rosier outlook. For instance, three planets are in the habitable zone of…

This star system will never be the Solar System

Astrophysics

Aug 2 2020

This star system will never be the Solar System

TYC 8998-760-1 might someday become something like our Sun. Right now, however, the young star is still a few billion years away from that. It’s been around for only about 17 million years. If it were the Sun, there would still be a long time before it would even be able to watch the dinosaurs. Nevertheless, the whippersnapper is still something special: astronomers using the European Southern Observatory’s (ESO) Very Large Telescope (VLT) photographed it and found two planets in its orbit. “Even though astronomers have indirectly detected thousands of planets in our galaxy, only a tiny fraction of…

Centaurs: they’ve been with us for a long time

Space

Aug 1 2020

Centaurs: they’ve been with us for a long time

We’ve been waiting for extraterrestrial visitors our whole lives – but in reality, they’re already here and have been with us for a long time. No, I don’t mean “Men in Black.” But it’s also not science fiction, it’s the truth. When astronomers discovered 2017 1I/ʻOumuamua, their surprise was enormous: we’d never seen an interstellar object inside our Solar System before. Or had we? We had. For some time, astronomers have known about asteroids that don’t orbit the Sun in the same plane as the planets (the ecliptic), but instead on orbits that are at a greater or smaller…

Meanwhile, in the outer edges of the Solar System

Space

Jul 31 2020

Meanwhile, in the outer edges of the Solar System

Gonggong, Quaoar, Orcus, Salacia, Gǃkúnǁ’hòmdímà, Leleākūhonua. You’ve probably never heard of the names of any of these worlds before (except for maybe Quaoar), but they are all very real celestial bodies that likely meet the definition of a dwarf planet and thus would have had the same claim to the title of “planet” as Pluto, right up until the time Pluto was demoted from planet status. The reason you won’t find them on any night-sky charts for amateur astronomers is because their orbits are so far away from the Sun that it was basically a miracle that any of…