Study Findings: The Barnard’s Star Planetary System: Stability, Composition, and Evolution of Four Sub-Earth Exoplanets

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Credit: NASA Photojournal

Monthly Notices of the Royal Astronomical Society abstract of study findings:

Barnard’s Star is the nearest single star to the Sun (1.8 pc⁠⁠), and hosts four recently discovered planets. The star also has well-characterized stellar abundances of important rock-forming elements, including Fe, Mg, and Si. For refractory elements like these, the planets have likely inherited similar bulk elemental abundance ratios to the star, facilitating modelling of their interior structures. We present here an analysis of the Barnard’s Star planetary system on several fronts. We perform a detailed stability analysis of the system, ascertaining that all four planets likely have masses between 0.19 and 0.84 M⁠, and are likely tidally locked, whereas a 4:3 mean-motion resonance chain for the inner three planets cannot be ruled out. Using atmospheric evolution models, we show that the prospect of extant primary atmospheres is highly unlikely on any of the planets. Barnard’s Star’s abnormally high Mg/Si ratio and low Th/Mg ratio imply planetary mantles which (a) are rich in (Mg,Fe)O ferropericlase; (b) have less than half the water capacity as Earth; (c) generate about half of the radiogenic heating as Earth; and (d) are cool and unlikely to have outgassed secondary atmospheres. Our analysis of this system presents an accessible set of first steps for the study of other nearby exoplanetary systems, as well as sub-Earth planets which will be increasingly discovered over the coming years.

Citation: Byrne, X., Guimond, C.M., Bonsor, A., et al. The Barnard’s Star planetary system: stability, composition, and evolution of four sub-Earth exoplanet. Monthly Notices of the Royal Astronomical Society, Volume 550, Issue 2 (2026).

DOI: https://doi.org/10.1093/mnras/stag1207

Study-related stories:

University of Cambridge – “Astronomers Find Nearby Planets To Be Small, Strange, and Utterly Uninhabitable”

Sci.News – “Barnard’s Star Planetary System May Be Filled with Water-Poor Rocky Worlds”

Daily Galaxy – “Scientists Studied a Nearby Star and Found Four Planets That Look Nothing Like Earth”

Sci-Fi Quote: Lt. Erica Ortegas and Strange New Worlds

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“I say that it’s not over, it’s never done, it’s never done. Because I always say the fans are the other half of what we do. So, I there’s a world for Ortegas that still exists, without giving anything away. She’s a character who I think was just a wonder to play. I’m so happy that they created the character in the first place. And as a pilot, as a maverick, as somebody who I have gotten to see has influenced so many younger fans, older fans, I keep saying it’s not over. There’s many places yet for Ortegas, and the world that she lives in to go.”

-Statement by Melissa Navia, who plays Lt. Erica Ortegas on Star Trek: Strange New Worlds, during an interview with Trekmovie. Season four of the Paramount+ series premieres on July 23rd. Filming for season five was completed late last year, with this final season of the series expected to be broadcast in 2027.

View of the Canadian Fires from Space

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Image (Credit): Image from July 14, 2026 showing the smoke from Canadian fires covering eastern parts of Canada and the U.S. (NASA Earth Observatory/Lauren Dauphin)

For those in the northeastern part of the United States, the impact of the ongoing Canadian fires is clear to see outside your window. A more distant view from a satellite (as shown above from earlier in the week) gives a better picture of what is occurring in Ontario and its impact on the surrounding region.

According to the latest data from the Canadian Interagency Forest Fire Centre (CIFFC), about 904 fires are currently burning across Canada, with 190 of the fires burning in Ontario.

Image (Credit): Wildland fire activity in Canada as of July 17, 2026. (CIFFC)

Pic of the Week: Chinese Probe Captures Earth’s Quasi-Moon

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Image (Credit): Image of asteroid 2016 HO3, also called Kamo‘oalewa, captured by a Chinese probe. (China National Space Administration )

This week’s image comes from a Chinese probe called Tianwen-2. It shows the spinning asteroid 2016 HO3, or Kamo‘oalewa, which is labeled by some of a “quasi-moon” of Earth until it decides to move on. Unlike the actual Moon, this asteroid is simply joining the Earth as it circles the Sun. The asteroid is about the size of a school bus.

The Chinese probe, launched from China in May 2025, is believed to have started its orbit of asteroid Kamo‘oalewa on June 6th of this year. It is now believed to be a rubble-pile asteroid, meaning it is basically loose material rather than a solid object. Even so, the Chinese probe may try to grab a sample to be returned to Earth in November 2027.

The source of the asteroid is still being debated, with some believing it is a piece of the Moon dislodged by an incoming asteroid while others believe it comes from the main asteroid belt.

In a paper released last year, scientists were leaning towards its origin being the main asteroid belt, noting:

Quantitative estimates show that population models of [Near Earth Asteroids] based on the migration of objects from the main belt are capable of accounting for Kamo‘oalewa-like objects. This relative contribution supports the hypothesis that (469219) Kamo‘oalewa originated from the main belt, which will be further investigated by future observations and in situ exploration of the Tianwen-2 spacecraft.

How long will it remain Earth’s partner? Back in 2021, Renu Malhotra, a UArizona planetary sciences professor, stated:

It will not remain in this particular orbit for very long, only about 300 years in the future, and we estimate that it arrived in this orbit about 500 years ago.

Space Quote: Dealing with Off-Planet Real Estate

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Image (Credit): One artist’s version of a Martian base. (NASA/JPL-Caltech/MSSS)

“So, who should have the right to acquire property in space? My answer: those who have the financial means to get there, develop, and use the land. For instance, if SpaceX succeeds in reaching Mars and starts to build permanent settlements on the red planet, then the ownership of land should go to SpaceX first. Not of the entire planet, of course, but of a practicable area, for example the size of Singapore. The surface area of Mars is 200,000 times that of Singapore, so SpaceX would initially only own 0.0005 percent of Mars. That would be enough to develop multiple settlements, but not so many that others would no longer have a chance.”

-Statement by Rainer Zitelmann, a historian and sociologist, in his Reason magazine article titled “Why You Can’t Settle Mars or Colonize the Moon Without Real Property Rights.” You do not need to agree with his conclusion, but he discusses a timely topic. The Moon Agreement and Outer Space Treaty may need to be revisited now that the idea of permanent settlements on the Moon and Mars are not simply science fiction, as they were in the 1960s and 1970s when these provisions were agreed to (and not by all nations, keep in mind).