Planet Euterpe, with its moon Musike in the distance
In a Nutshell:
Euterpe /juˈtɝpi/ is a conworld idea I've been working on for a while. The main purpose is to create an intelligent species that communicates primarily through sign languages. Disclaimer: I'm not there yet. I've mostly finished astronomical details, and I'm going to work on the evolutionary tree next. This is a "bottom up" project. I want to flesh out all the necessary background information before I start trying to describe specific cultures and their languages.
If you were to set foot on the surface of Euterpe, this is what you would immediately notice: You would feel slightly heavier, with 1.2 g pulling down on you. It's a balmy 30° C outside (86° F). You may find it hard to breathe (or, in fact, deadly) with the high amount of greenhouse gases, especially carbon dioxide. Bring an air tank, because the air is around 31% oxygen. If you look up, you will see a white sky and a large, somewhat dim, orange sun. At sunset, the sky turns deep red. The atmosphere is thicker than Earth's, which is why it makes these colors. You are surrounded by dense plant life. The plants have large purple or black leaves, to absorb as much light as possible from the star. On the horizon, an enormous storm cloud is accumulating. The wind speeds are picking up, and you are almost knocked over. The tree-like plants are short with wide trunks to stay upright in the frequent storms.
The planet is somewhat uniform from the equator to the poles, compared to Earth. The thick atmosphere, extensive oceans, low axial tilt, and fast rotational period all help regulate the air temperature. The average surface temperature is 19°-25° C, depending on the planet's location around the star. The crust is thinner than Earth's, which causes more volcanic activity. The volcanoes dump more CO2 into the atmosphere, which creates the high greenhouse effect. According to Universe Sandbox (a space simulator I made the system in), the greenhouse effect heats up the planet by 88° C (compared to 33° for Earth). Cloud cover is dense, and rainstorms are common and short. Lightning strikes easily create wildfires, which burn easily in the high-oxygen air.
Star System Information
There are nine planets, named after the Nine Muses in Greek mythology: Calliope, Clio, Euterpe, Erato, Melpomene, Polyhymnia, Terpsichore, Thalia, and Urania. The star is, of course, named Mnemosyne, after the mother of the muses. Here's some basic info about each planet. I'm using numbers relative to familiar solar system objects to give you a basic idea of what they're like, without boring you with specific values.
Mnemosyne: A K1 main sequence star. It is smaller, less massive, and dimmer than the sun.
Calliope: A rocky planet about 2.1x the mass of Earth. It is the closest planet to the star, and it is tidally locked.
Clio: A rocky planet 3.7x the mass of Earth. It has a very high axial tilt. No atmosphere. It has a small moon, presumably a captured asteroid.
Euterpe: The Earth-like one. Roughly 1.8x Earth's mass. Large global ocean. Lots of volcanoes. 12.5° axial tilt. A Euterpic (?) day is 0.73x an Earth day. A year is equal to 303.3 Earth days. There are no permanent ice caps, and snow is rare.
Musike: Euterpe's moon. It is so named because Euterpe is the muse of music and lyric poetry. (Three other muses also seem to be credited with lyric poetry, though.) It is smaller than our own moon, with a radius of 1434 km. It is tidally locked to Euterpe.
Erato: A small planet, 6.9x the mass of the moon (1.7x the moon's radius).
Melpomene: A ball of ice. 0.8x Earth's mass. It has a thin atmosphere and three captured asteroid moons.
Polyhymnia: The first gas giant. It is 1.7x the mass of Jupiter. Brown in color.
Terpsichore: A gas giant 17x the mass of Earth (7.6x Earth's radius). Also brown.
Thalia: A small gas giant, 6.2x Earth's mass. Light blue.
Urania: Neptune-like. Has a mass 17x that of Earth.
Here are some images of the system, to scale:
Outer system, with gas giants:
I don't know exactly what they should look like yet, because I want to evolve them first. Like I said, this is a bottom-up project. I do have some preliminary ideas about how sign language will affect their culture as a whole. The following is copied and pasted (and modified) from the conculture ideas thread:
Vocalizations could be used for emphasis, onomatopoeia, and getting someone’s attention. Some simple messages could be conveyed vocally, like “Stop,” “Hello,” “Help me,” “Excuse me,” etc, and highly specialized trade-specific signals. The only communities to use spoken languages are blind people. Unfortunately for them, their vocal parts did not evolve for talking, so this is very difficult. Some blind communities opt for tactile signing. Deaf individuals have almost no problem navigating daily life.
Communicating while using one's hands for something else would be akin to talking with your mouth full.
They would still have written language, but I imagine it would look something like ASLwrite. Just as some human scripts leave out information (such as vowels for abjads), some Euterpic scripts leave out one or more of the following: hand shape, hand orientation, hand location, and/or hand movement. If a script is not logographic, hand shape is almost universally the first thing to be represented. Orientation, location, and movement are secondary, and often represented with diacritics.
Singing and dancing would be combined into "Signdancing". It would use rhythmic, exaggerated hand movements and body/foot movements. Instead of bands having a lead singer, they would have a lead "signer." (Something like this, minus the actual singing, of course.) The implications for poetry are pretty beautiful too, in my opinion. See here
Individuals that break/lose one or both of their arms (assuming this species has two arms) would have a difficult time communicating.
Props to you if you read all of this. It's a work in progress, but I have plenty of time over the holidays to continue working on it. Thanks for reading! Up next: Plate tectonics.