Have you ever wondered if we might one day find a new planet on the edges of our solar system? This edition of Core Elements highlights developments in the search for Planet Nine beyond Neptune (and what that planet may be like), and how to address the issue of man-made space debris circling Earth.
Rasoul Sorkhabi
Editor, Core Elements
The Search for Planet Nine
Vadim Sadovski/ Shutterstock.com
In 2006, research by Caltech astronomers Mike Brown and Konstantin Batygin led the International Astronomical Union to demote Pluto to a dwarf body. Later, Brown’s young daughter suggested a way for his dad to seek redemption for his reputation: “Go and find another planet.”
The problem with Pluto: Pluto lost its major planetary position because it is a dwarf among other comparable dwarfs called the Extreme Trans-Neptunian Objects (ETNOs). Varuna, Quaoar, Sedna, Orcus, Alicanto, and Eris were the first six dwarfs discovered from 2000–2005.
After two decades, Brown, Batygin and colleagues are very close to discovering a mysterious Planet Nine (also called Planet X) beyond Neptune.
Signs of Planet Nine: Evidence for the existence of Planet Nine is not from observing it directly but observing its gravitational effects indirectly. This evidence includes:
The orbital planes of the observed 14 ETNOs are “ecliptic”—that is, they are tilted by about 18 degrees from the plane of our solar system’s planets, and their perihelia (closest distance to the Sun) are alighted.
This clustering may be a coincidence, but last year, Batygin and Brown hypothesized that Planet Nine’s gravitational pull also explains the orbital motion of asteroids closer to Neptune, which cannot be explained by Neptune’s influence alone.
Comparison with Earth: If Planet Nine exists, its composition is likely similar to other ETNOs—a mixture of rocks and volatile ices (water and methane) coated with organic matter.
Planet Nine will probably:
Be ten times heavier than Earth
Have a radius 3.7 times larger than Earth’s radius
Have a calendar year 10,000–20,000 times longer Earth’s year
Have a distance from the Sun of 400–800 astronomical units
Have an average temperature of -226 C (compared to 15 C on Earth)
What’s next: This year, a new powerful telescope called the Vera C. Rubin Observatory will start probing from atop Cerro Pachón—an 8,700-foot-mountain in Chile.
The telescope is equipped with a 3,200-megapixel camera, the largest on Earth, which was transported from California in May 2024.
Rubin will illuminate our view of ETNOs, discovering thousands of new bodies, including perhaps Planet Nine or whatever new name it might be given.
A message from AAPG Academy and AWS For Energy and Utilities
Join AAPG Academy and Amazon Web Services for Energy and Utilities for a freeupcoming webinar on 27 February at 9am CST to learn more about how cutting-edge AI applications are empowering geoscientists to drive critical business decisions.
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Using AI to transform complex data into actionable insights
Moriba Jah, professor of aerospace engineering at The University of Texas at Austin, has discussed the problem of space debris and suggested some solutions in Scientific American.
By the numbers:
Today, there are more than 10,500 active spacecraft and more than 25,000 pieces of man-made junk (each larger than 10 centimeters) circling Earth.
Earth’s orbital space is consumed by a few organizations—notably SpaceX, OneWeb, and Amazon’s Project Kuiper—which operate the majority of working satellites.
SpaceX and Amazon plan to launch tens of thousands more satellites to provide a global broadband network.
Hazard analysis:
The space debris, depending on its type and orbit, circles Earth at speeds of 2,500 to 17,500 miles per hour—much faster than bullets.
They may collide with working or abandoned satellites and create more debris. In 2009, there was a catastrophic collision between the Iridium satellite and the defunct Russian satellite Kosmos 2251.
The debris may re-enter Earth in an uncontrolled manner and cause damage. In 2024, a part of the International Space Station fell through the roof of a house in Naples, Florida.
Toward solutions: Jah suggests the following for a “circulatory space economy” and “sustainable space practices:”
Design spacecraft that generate less waste
Repair satellites’ broken parts in orbit to extend their lifecycles
Recycle material from defunct satellites for use on new missions
Retrieve and reprocess space debris to reduce collision risks
Last week’s quiz question was: Serpentinite is the state rock of which U.S. state and what is the geologic reason for that?
Answer: Serpentinite is the state rock of California, because of the abundant serpentinite and other ocean-floor accretionary rocks—the Jurassic-Cretaceous age Franciscan Complex—in California. Incidentally, last week I saw some outcrops of these serpentinites and deep ocean rocks during a visit to the Golden Gate Bridge in San Francisco.
Now for this week’s quiz question: How do we define the uppermost boundary of Earth’s atmosphere? How high is it above Earth’s surface?
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