Holland in the Sky: Night Watch and Starry Night
Since December 17, 2019, the Netherlands has two new far outposts: the planet Night Watch and the star Starry Night. The IAU, the International Astronomical Union, asked us to come up with a name for those two celestial bodies, which were previously known under the somewhat boring character combinations HAT-P-6 and HAT-P-6b. Inhabitants of the 111 other countries affiliated with the IAU were also assigned a cosmic duo, as part of the NameExoWorlds campaign. The Dutch public came up with some interesting suggestions for “our” planet and star
Rembrandt and Van Gogh
Out of 6,000 suggestions submitted, the national jury chose a shortlist of five name twins, of which Nijntje (Miffy) and Moederpluis (Mother Bunny) were the most popular in an election. But on second thought, that wasn’t such a good idea, for legal reasons. And so it became Night Watch and Starry Night, after the famous paintings by Rembrandt and Van Gogh. With the added advantage that these names, with all thier ch-sounds, are virtually unpronouncable for foreigners.
We cannot go there, at least not in the foreseeable future: Nachtwacht and Sterrennacht are 910 light-years away. So even a spaceship that can travel at the speed of light takes almost a millennium for a one way trip.
The star is visible with a telescope, the planet is not; it was discovered by subtle variations in the brightness of its mother star. It’s amazing how many precise data about the layout and dimensions of Nachtwacht can be derived through this method. The planet is 1.33 times as large as Jupiter: its diameter is 190,000 kilometers. The distance to Sterrennacht is only 7,800,000 kilometers, one twentieth of the distance from the Earth to the Sun. Its orbital period is therefore very short: a year on Nachtwacht is slightly shorter than four Earth days.
What Nachtwacht looks like: we have no idea. It is most likely a gas giant, something like Jupiter but a little bit bigger. A sphere with no fixed surface and with cloud bands in the rotational direction of the planet. The same visualization pops up in every media report and on Wikipedia, showing a typical gas giant. To me it seems to be drawn too close to its star, probably for the dramatic effect.
But if we do not know for now, we can of course assume that the cloud bands on planet Nachtwacht are alternately red, white and blue, the colors of the Dutch flag. I leave it to the planetary scientists to find out what chemical processes in the atmosphere would cause that striking color scheme. Earth’s water clouds are white, the atmosphere of Neptune has the right shade of blue so especially the red is still a mystery. Anyway, I just came back from a virtual voyage I made to the planet in order to produce an alternative artist impression.
We also see two of Nachtwacht’s moons on this picture. Their existence has not yet been scientifically proven, but they will undoubtedly be there; the gas giants in our own solar system also have dozens of them. I propose naming those satellites after characters in the painting Night Watch. I call that light gray one top right Schellingwou, the purple one on the left in the background is called Wormskerk.
And that bright spot at the bottom right, what’s that? To be honest, I don’t really know. Is it a spaceship? A tiny moonlet? A photon torpedo? Or just a lens effect? Well, it’s good to have at least some mysteries left.
The orange planet
But of course the Netherlands have another national color: orange. Originally the color of our royal family, but also ubiquitous in sports competitions in which one or more Dutch athletes participate. Only questioned by people who are both republican and sports hater…
Most likely Starry Night has more planets than just Nightwatch. That required a new visualization, of an orange planet. From the looks of it, this is a somewhat smaller world, a rocky planet roughly the same size as Earth. But other than that there’s not much Earthlike about this sphere.
It seems to me to be a geologically very active planet, with a kind of spiraling plate tectonics. With light and dark areas, where the latter could be a kind of seas. The bubbling gas bubbles also seem to indicate this. On the night side, the “seas” appear to be somewhat luminous, which may be related to a rather high temperature.
The planet has an atmosphere and also clouds be observed. But whether that atmosphere can be breathed by people seems very doubtful to me. I would advise explorers to bring a solid spacesuit with a good cooling system.
And what is this orange world called? My suggestion, to stay with the theme: The Girl with a Pearl Earring.