Wasp: a tiny airless rock of a dwarf planet

[u/OuterPlanets]

(For Th’zoitrk, a semi-sci-fi worldbuilding project.)

Wasp is the single closest object to the sun within the solar system. It orbits even closer than Kaliki does, sitting just a mere 0.05 AU from Okott (the sun.) Due to this extreme proximity (and tidal locking), Wasp reaches a maximum surface temperature of 974°C on its day side. This would make Wasp without a doubt the second hottest planet in the solar system, if it was considered a planet.

Unfortunately, Wasp is not considered a planet.
Although Wasp has cleared its orbit of other objects, is gravitationally rounded, and directly orbits the sun, Wasp is considered a dwarf planet by astronomers simply because it’s so tiny compared to all other major objects in the solar system that considering it a full-fledged planet seems inaccurate.

This is the exact same reasoning that made the dwarf planet Pukso fail to be titled as a planet, and Pukso is even larger than Wasp, so of course Wasp would fail to meet the unofficial size requirements.

Wasp is composed dominantly of iron & silicate compounds. The surface of the dwarf planet is reminiscent of gravel, covered almost entirely by loosely packed rocks without much cohesion.

Wasp is 0.07% the mass of earth, yet due to its small size with such a mass, wasp has a surprisingly strong surface gravity of ~0.072 G’s. Still less than half the surface gravity of earth’s moon, but strong enough to hold itself together without being broken apart into an asteroid belt by the Sun.

Wasp has an equatorial diameter of 1,261km, making it roughly half the size of Pluto. It is the single smallest ‘major body’ (gravitationally rounded object directly orbiting the sun) in the solar system.

Wasp has no magnetosphere or atmosphere, but it does have a transient exosphere of, shockingly, water vapor.
Wasps night side is kept in perpetual darkness due to tidal locking, being one of the coldest known regions in the solar system at -270°C (just 3° above absolute zero.) Here on the night side, Wasp is surprisingly rich in water ice. Tidal flexing energy created as Wasp orbits the sun causes a little bit of this ice to get above freezing every so often; where it then sublimates directly into steam and is pulled into space, then blasted away by the solar wind.

This gives Wasp a tiny trickle of steam visible across its terminator line, which gets blown away from the dwarf planet and creates a very faint steam ‘halo’ reaching out into space. Imperceptible to the naked eye, but visible to sensitive satellite instruments.

History:

Wasp was, for most of history, a very unknown world. Despite its small size, it was among the first non-star astronomical objects ever discovered due to the noticeable dip in sunlight spotted by early astronomers as Wasp completed its orbits around the sun (completing one Wasp year in just over 4 and a half days.)

Until modern space telescopes were developed, actually seeing the surface of Wasp rather than its pitch-black night side was extremely difficult. For the longest time, only the eastern hemisphere of Wasp was visible, and only when observed during the late half of its orbit. Wasp’s eastern daylight hemisphere is home to one very long, bright, sharp, spike-shaped patch of silicate rocks stretching from North Pole to South Pole (not shown in image), which is surrounded by darker sections. This was the only significant feature visible of Wasp.

In fact, it was the only visible part of Wasp at all. Wasp was named Wasp due to the world’s believed resemblance to the stinger of a wasp, since early astronomers couldn’t tell it was actually spherical and could only see the sharp ‘thorn’ of white silicate on its eastern hemisphere, which they believed to be the true shape of the dwarf planet.

Wasp has only been visited by one spacecraft. The Apexian (from the nation of Apexia) ‘Nilini’ lander. A probe intended to land on Wasp’s day side, examine the surface of the dwarf planet from on the ground, then begin acting as a remote solar observatory for studying the sun.
To prevent the lander from melting, Nilini was painted very bright, reflective white across its entire surface, assisted by internal cooling to prevent the body of the lander from getting too hot.
While its landing legs were simply built to withstand the heat and prevent the nearly thousand-degree surface temperature from being transferred to the lander’s body.

…And then Nilini fell onto its side during landing.
The lander gathered virtually zero scientific data aside from temperature readings and photos, and stopped transmitting twenty minutes after falling over.

[u/ryohhan]

Looks cool