Let’s Build a World: New Astronomical Finds for Your SF Stories

I’ve got a file (actually a dozen files) of cool science stories that I might use in science fictional world-building. What sf author doesn’t? Even fantasy stories need good science. For instance, an urban fantasy involving werewolves really should depict the phases of the moon accurately. This week, images and data from the Hubble and James Webb Space Telescopes have furnished a treasure trove of research ideas. Rather than post them separately, I’ve gathered a few that I find particularly exciting.


There Could be Many Water Worlds in the Milky Way

Astronomers are curious about how many terrestrial planets in our galaxy are actually “water worlds.”
These are rocky planets that are larger than Earth but have a lower density, which suggests that volatiles like water make up a significant amount (up to half) of their mass-fraction. According to a recent study by researchers from the University of Chicago and the Instituto de Astrofísica de Canarias (IAC), water worlds may be just as common as “Earth-like” rocky planets. These findings bolster the case for exoplanets that are similar to icy moons in the Solar System (like Europa) and could have significant implications for future exoplanet studies and the search for life in our Universe.

“We have discovered the first experimental proof that there is a population of water worlds, and that they are in fact almost as abundant as Earth-like planets. We found that it is the density of a planet and not its radius, as was previously thought, which separates dry planets from wet ones. The Earth is a dry planet, even though its surface is mostly covered in water, which gives it a very wet appearance. The water on Earth is only 0.02% of its total mass, while in these water worlds it is 50% of the mass of the planet.”

However, planets around M-type stars typically orbit so closely that they are tidally locked, where one side is constantly facing toward its sun. At this distance, any water on the planet’s surface would likely exist in a supercritical gas phase, increasing their sizes. As a result, Luque and Pallé theorized that in this population, water is bound to the rock or in closed volumes below the surface, not in the form of oceans, lakes, and rivers on the surface. These conditions are similar to what scientists have observed with icy moons in the outer Solar System, such as Jupiter’s moon Europa and Saturn’s moon Titan.

Given that they are tidally locked to their suns, these planets may also have liquid oceans on their sun-facing side but frozen surfaces everywhere else – colloquially known as “eyeball planets.” While astronomers have speculated about the existence of this class of exoplanet, these findings constitute the first confirmation for this new type of exoplanet. They also bolster the growing case for water worlds that form beyond the so-called “snow line” in star systems (the boundary beyond which volatile elements freeze solid), then migrate closer to their star.

In the past, glaciers may have existed on the surface of Mars, providing meltwater during the summer to create the features we see today. Credit: NASA/JPL-Caltech/ESA

Mars Had Moving Glaciers, but They Behaved Differently in the Planet’s Lower Gravity

On Earth, shifts in our climate have caused glaciers to advance and recede throughout our geological history (known as glacial and inter-glacial periods). The movement of these glaciers has carved features on the surface, including U-shaped valleys, hanging valleys, and fjords. These features are missing on Mars, leading scientists to conclude that any glaciers on its surface in the distant past were stationary. However, new research by a team of U.S. and French planetary scientists suggests that Martian glaciers did move more slowly than those on Earth.

These findings demonstrate how glacial ice on Mars would drain meltwater much more efficiently than glaciers on Earth. This would largely prevent lubrication at the base of the ice sheets, which would lead to faster sliding rates and enhanced glacial-driven erosion. In short, their study demonstrated that lineated landforms on Earth associated with glacial activity would not have had time to develop on Mars.
In addition to explaining why Mars lacks certain glacial features, the work also has implications for the possibility of life on Mars and whether that life could survive the transition to a global cryosphere we see today. According to the authors, an ice sheet could provide a steady water supply, protection, and stability to any subglacial bodies of water where life could have emerged. They would also protect against solar and cosmic radiation (in the absence of a magnetic field) and insulation against extreme variations in temperature.

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