EXOPLANETS
Jon witnesses a total pulsar eclipse from a planet that’s as hard as diamond
Our trip this time takes us 1,200 lightyears from Earth to the constellation of Serpens Cauda, the serpent’s tail. Here lies one of those objects that bullies and pushes our notions of the laws of physics to their limit: a spellbinding millisecond pulsar, 1.4 times the mass of the Sun.
It can be hard to focus our sometimes plodding perceptions around these extraordinary objects. Despite being almost 50 per cent more massive than the Sun, this pulsar, PSR J1719-1438, is only 20km in diameter – about the size of Guernsey. PSR J1719-1438 spins at a mind-shredding rate of 10,000 rotations a minute. Astronomical extremes at their most enthralling.
A remarkable planet sits very close to the luminous violence of this parent pulsar. First observed in 2009 using the technique of pulsar timing, planet PSR J1719-1438 b orbits once every two hours at 0.004 astronomical units. It’s highly likely to be a carbon world; diamond and crystallised carbon make up a great amount of its composition.
Steering my ship, the Perihelion, to the surface of this extreme object, which is four times the radius of Earth, it feels like a compressed gas giant, compacted into a cosmic-scale diamond. A planet 20 times as dense as Jupiter and only 1.02 times its mass, it’s amazing to contemplate how very hard this planet really is! If we ever tried to mine the planet for chunks of its diamond structure, we would need some unfathomably specialist gear; even a light sabre would struggle to cut it out. A less challenging job might be reducing Krakatoa to powder using only a nail file.
Its appearance straddles the border of severity and serenity. Evocative of Metebelis 3, the famous (fictional) blue planet of the Actean Galaxy visited by Jon Pertwee’s third Doctor a few times, this world is charged with a sharp, silvered, royal blue glow. It feels like an electric shock made visible.
This alien sky doesn’t have a hostile feeling about it; moreover it exudes a sense of caution. It would be all too easy to be captivated by the silvery beauty, but you would be sealing your doom if you idled away too much time on the surface of J1719-1438 b unprotected. Because what you’re actually seeing is the monochrome glow of deadly radiation. It’s not only a fascinating view that we’d be absorbing! With this in mind, the Perihelion’s radiation shields are reinforced and set to maximum.
A beguiling event takes place as a moon of this diamond pulsar planet makes a transit of the parent pulsar. Another first for our exoplanet excursions: a total pulsar eclipse! This one’s a black hole in an alien sky, looking like some kind of porthole to a neighbouring universe. Over a planetscape with the appearance of a choppy ocean frozen in time, the pulsar’s maddening, flickering light is gracefully interrupted.
With the parent pulsar covered by what’s probably a Pluto-sized moon, it looks like an Olympic shot putter has made a night-time, record-breaking throw in front of some remote lighthouse, the action freeze-framed at precisely the perfect moment.