New Findings on Eris and Makemake: Surprising Discoveries about Dwarf Planet Surfaces
In the far reaches of our Solar System, dwarf planets like Pluto have always been considered cold and inactive. However, recent findings from the James Webb Space Telescope suggest that these distant celestial bodies may be more geologically active than previously thought. The telescope’s capabilities allowed researchers to analyze the hydrogen isotopes present on the surfaces of Eris and Makemake, two dwarf planets in the Kuiper Belt.
The Kuiper Belt is a region of the Solar System where objects formed far away from the Sun, resulting in icy compositions. Unlike the inner planets, which are predominantly gaseous, these objects are composed of solid ices such as nitrogen, methane, and carbon dioxide. Due to their small size and distance from the Sun, any heat they initially possessed dissipated quickly. However, the New Horizons mission to Pluto revealed surprising geological features on its surface, indicating that even a small amount of heat can drive geological activity.
Eris and Makemake, similar to Pluto, are located in the Kuiper Belt. Eris is nearly as large as Pluto and orbits at over twice Pluto’s closest approach to the Sun. Makemake, on the other hand, orbits at a distance one and a half times Pluto’s closest approach. Sending a mission to either of these dwarf planets would take decades, making it difficult to study their surfaces directly. However, the James Webb Space Telescope has provided valuable insights into their compositions.
By imaging sunlight reflected off Eris and Makemake and analyzing their infrared spectra, researchers were able to determine the chemical composition of their surfaces. The presence or absence of certain chemicals can be inferred from the spectrum dips at specific wavelengths. Surprisingly, both dwarf planets showed an abundance of methane ice on their surfaces but lacked carbon monoxide, which is typically found in comets originating from the Kuiper Belt. This discrepancy suggests that something unusual is happening on the surfaces of Eris and Makemake.
Additionally, the absence of more complex organic molecules, such as ethane, ethylene, and acetylene, was unexpected. These molecules are typically formed when methane is exposed to radiation. Water, carbon dioxide, and ammonia were also notably absent from the spectrum. However, this does not necessarily mean that these chemicals are entirely absent from the dwarf planets’ surfaces; they may simply not be major components.
To further investigate these findings, researchers analyzed the isotopes of carbon and hydrogen in methane on Eris and Makemake. Isotopes are different versions of an element with varying numbers of neutrons. The ratios between these isotopes can provide insights into the origins and history of a celestial body. Surprisingly, the hydrogen-to-deuterium ratios on Eris and Makemake were much lower than expected for early Solar System material.
The researchers proposed a possible explanation for these findings. They suggested that water on Eris and Makemake could have reacted with simple carbon compounds or participated in the breakdown of complex organic chemicals, resulting in the formation of methane with similar isotope ratios to water found elsewhere in the Solar System. However, these reactions would require temperatures significantly above the boiling point of water, which is unexpected for icy bodies like Eris and Makemake.
Nevertheless, estimates of radioactive decay in the rocky cores of these dwarf planets suggest that sufficiently high temperatures could have been reached in their history. This is especially true for Eris, which has a high density indicative of a large rocky core. The presence of internal heat could have created a sub-surface ocean and driven circulation in the ices of the crust, bringing methane to the surface.
The researchers speculate that this process may still be ongoing, explaining the absence of complex organic chemicals on the surfaces of Eris and Makemake. While it does not necessarily involve a sub-surface ocean, it does require enough heat to cause circulation between the surface and the core/crust boundary.
It is important to note that these findings are based on assumptions and approximations and should not be considered definitive. Further studies and a better sampling of material from comets, which share similar chemistry with these dwarf planets, would provide more insights into their compositions.
Nonetheless, these discoveries challenge our previous understanding of dwarf planets and highlight the remarkable capabilities of the James Webb Space Telescope. As our knowledge of icy bodies in the Solar System expands, it becomes clear that geological activity can occur even in the coldest and most distant corners of our cosmic neighborhood.