Space

Sep 11 2020

Panspermia: colonies of bacteria can survive in interplanetary space

Deinococcus radiodurans is one tough bacterium. Neither the detonation of atom bombs nor the terrors of empty space bother it. But could it travel from planet to planet as a stowaway? Imagine microscopically small lifeforms being transported through space and landing on another planet. Bacteria that find suitable conditions for their survival on the new planet could then multiply and spawn life on the other side of the universe. This theory, which is known as “panspermia,” postulates that microbes could travel between planets and spread life throughout the universe. Panspermia has been debated for a long time, because it obviously…

Milky Way vs. Andromeda: the collision has already begun

Astrophysics

Sep 10 2020

Milky Way vs. Andromeda: the collision has already begun

It’s inevitable that the Milky Way and the Andromeda Galaxy will one day collide and merge, even though right now there’s still 2.5 million light-years between them. Thus, the light that we see from Andromeda today was emitted from there 2.5 million years ago. The two most massive members of the Local Group are approaching each other at 120 kilometers per second. In three to four billion years (so while our Sun is still alive), up to 1.3 billion stars of the two galaxies will encounter each other. After another maybe three billion years, the merger will produce a…

More rogue planets than stars in the Milky Way?

Space

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…

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,…

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…