EX PLANET EXCURSIONS
Jon visits a world very much like Venus, but also mercifully very different
After the serenity of the TRAPPIST-1 system, 39 lightyears from Earth, I thought that my ship and I would benefit from a journey somewhere farther afield. And I’ve got the perfect destination in mind: Kepler 1649b.
This world holds a particular fascination for me because of the similarities it shares with Venus. It orbits the star Kepler 1649, which is 219 lightyears away in Cygnus. Kepler 1649 is smaller than our Sun, around a quarter of its size and mass. It’s a faint little star that shines at mag. +17.3, so a rather substantial scope would be required to observe it from Earth.
The planet, which is an estimated 1.08 Earth radii, receives the same amount of starlight as Venus does from the Sun, which makes me wonder. How similar to our hellish, sulphuric acid raining, runaway greenhouse effect, evil sibling Venus is it?
For all the similarities, there are some important differences too. The planet is much closer to its star than Venus is to the Sun, just 0.05 AU, completing an orbit every nine days. It receives lower levels of radiation than Venus, since its home star emits energy at lower frequencies than the Sun. Kepler 1649b is also cooler than the Sun (thermally, not culturally) at around 3240 Kelvin. Such a close orbit has tidally locked this world. The planet also appears to have some quite robust geological activity going on. Evidence of volcanic activity like Io’s can be seen: yellow, shining, vein-like growths flecked across the night side of the planet. Tidal heating could well be taking place here.
There are breaks in what appears to be a thin atmosphere enveloping the planet. The breaks fit together in a formation like a pastry lattice, giving tantalising views of the planet’s surface below. Unlike molten planets, Kepler 1649b looks hard-baked and smouldering.
Allow me to be tangential for a moment. As a seven-year-old I was fascinated by a giant, industrial boiler at a mushroom farm where my dad worked. It had an outer viewing tube which allowed the ferocity of the fire inside to be seen. This was amazing to watch. I thought of the machine as being like an indoor, man-made volcano. One moment there’d be the dazzling, solid yellow light of the fire visible through this tube. When the firing cycle ended, there’d be a bright amber heat shine gradually fading from yellow to orange to red, then brown – like moonrise in reverse. The surface of Kepler 1649b appears very much like this. Patches of varying heat intensity, blended together like giraffe markings. An incredible and unusual planetary surface to behold.
I hover the Perihelion at a point on the planet’s night side where I can safely observe. The sky is overcast and what appears to be deep red cotton wool. Below that is a clear zone of vivid orange like a glassblower’s oven with the area leading to the horizon, as well as the horizon itself, festooned with gold sparks of distant volcanic activity. It’s like a soothed version of Venus. Less violent and more beautiful.