Why does Iapetus have two colours?

Iapetus is the third largest satellite of Saturn, and it is the largest object in the solar system not in hydrostatic equilibrium. Iapetus is a moon of Saturn known for its colour dichotomy. It has a dark side and white side, and it is often called the Yin Yang moon.

What makes the worlds seem round?

Are Mimas and Miranda the smallest known objects in hydrostatic equilibrium? Dan – London This question relates to the shape of astrophysical objects and as we discussed in the past, it’s an important characteristic of stars, and it’s in the definition of “planet”. An object is round if it has hydrostatic equilibrium, meaning the pressure generated by…

Destroying the One Ring in Space

I was asked by Larry, one of my students, about what would be the best place in the solar system to destroy the One Ring. Since the 25th of March is the anniversary of its destruction and the fall of Sauron I thought I’d dedicate this vlog to answering the question as seriously and as accurately as possible.

Time management.

“Can you build me a hyperbolic time chamber? I’ll buy you a coke.” Friend of mine while we were walking down the street. Almost 110 years ago our view of time was changed forever. Time wasn’t part of the immutable stage of life but it was an active player. We finally understood how to squeeze…

Can a satellite hover over the Sun?

My friend Russell asked me under which condition an object would be able to stand still around the Sun. This is a very interesting question; it probes some fundamental facts about the solar system and its applications are keeping many engineers around the world busy. Planets go around the Sun due to Sun’s gravitational field.…

The most dangerous club in the Universe

What would a planet orbiting a pulsar look like from the ground? Would it look like a giant disco planet with a constant strobe light? Pulsar form from supernova explosions, and they are neutron stars that spin on their axis thousand time per second. They are highly magnetised and the precession of the magnetic field…

Colliding stars

I know that likelihood of stars colliding is very low, but have there been papers describing the theoretical process of star collision? James, London I think we can divide star-collision into three classes: Stellar Mergers Binary collisions Stellar Collision Under the stellar merger label we include the theoretical stars which are formed in tightly bound…

All about the Asteroid Belt

What does it actually look like in the asteroid belt? Is it anything like as dense as is shown in films? Or is it more like you can see one or two rocks in the distance? Matthew, Amsterdam Contrary to popular belief, the asteroid belt is mostly empty and it’s not the crammed zone of…

How big is the biggest galaxy in the Universe?

If by big we mean physical dimension, the largest known galaxy is most likely IC1101. IC1101 is gargantuan even among galaxies; it’s a super elliptical galaxy with a diffuse stellar halo that to extends to at least 1.4 million light years. The Milky Way’s halo by comparison extends to about 100.000 lights years. In the picture we…