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Our Solar System Expands

By David Reneke

A new dwarf planet has been identified in our solar system, and a new theory suggests that life on Earth may have developed prematurely from a cosmic perspective.

A team of scientists has identified a new member of our solar system, a dwarf planet lurking 13.6 billion km from the Sun. This new world, classified as 2014 UZ224, takes 1100 years to complete one orbit of the Sun, and could soon join the ranks of the five established dwarf planets in the solar system: Ceres, Eris, Haumea, Makemak, and, most famous of all, Pluto.

Was this a lucky find? Definitely not! There could be at least 100 more lurking in the Kuiper Belt, that mysterious region beyond the orbit of Neptune thought to be teeming with comets, asteroid and small planetary bodies.

The team, led by Prof David Gerdes of The University of Michigan, had pinpointed 2014 UZ224 in an enormous map of galaxies created by a project called the Dark Energy Survey. To spot something so relatively small in a map this size you’ve just got to look for something that’s moving.

The team then used specialised computer software to connect the dots and confirm that what they were looking at was a single object. This took years to figure out.

“We often just have a single observation of the thing, on one night,” said Gerdes. “And then two weeks later one observation, and then five nights later another observation, and four months later another observation. So the ‘connecting the dots’ problem is much more challenging.”

The discovery has now been confirmed by the International Astronomical Union, but whether it will let 2014 UZ224 join the ranks of the five established dwarf planets in our solar system is another matter. The most important distinction for a dwarf planet is that it’s large enough to have become round due to its own gravitational attraction.

US astronomer Mike Brown successfully campaigned for Pluto to be downgraded to a dwarf planet in 2006, arguing that anything larger than 400 km in diameter in the Kuiper Belt is round and could therefore qualify as a dwarf planet. 2014 UZ224’s diameter is around 530 km, just outside the minimum requirements, and therefore could be eligible for planetary status.

Is Earthly Life Premature from a Cosmic Perspective?

The universe is 13.8 billion years old, and our planet formed just 4.5 billion years ago. This time gap means that life on other planets could be billions of years older than ours, but new theoretical work suggests that life on Earth is premature from a cosmic perspective.

“If you ask, ‘When is life most likely to emerge?’ you might naively say, ‘Now,’” says Prof Avi Loeb of the Harvard-Smithsonian Centre for Astrophysics. “But we find that the chance of life grows much higher in the distant future.”

Life as we know it first became possible about 30 million years after the Big Bang, when the first stars seeded the cosmos with elements like carbon and oxygen. Life will end 10 trillion years from now when the last stars fade away and die. Loeb and his colleagues considered the relative likelihood of life between those two boundaries.

The dominant factor proved to be the lifetimes of stars. The higher a star’s mass, the shorter its lifetime. Stars larger than about three times the Sun’s mass will expire before life has a chance to evolve.

Conversely, the smallest stars weigh less than 10% as much as the Sun. They will glow for 10 trillion years, giving life ample time to emerge on any planets they host. As a result, the probability of life grows over time. In fact, the chances of life are 1000 times higher in the distant future than now.

“Why aren’t we living in the future next to a low-mass star?” Loeb asks. “One possibility is we’re premature. Another possibility is that the environment around a low-mass star is hazardous to life.”

Although low-mass red dwarf stars live for a long time, they also pose unique threats. In their youth they emit strong flares and ultraviolet radiation that could strip the atmosphere from any rocky world in the habitable zone.

To determine which possibility is correct – our premature existence or the hazard of low-mass stars – Loeb recommends studying nearby red dwarf stars and their planets for signs of habitability. Future space missions like the Transiting Exoplanet Survey Satellite and the forthcoming James Webb Space Telescope should help to answer these and other similar questions.


David Reneke is an astronomy lecturer and teacher, a feature writer for major Australian newspapers and magazines, and a science correspondent for ABC and commercial radio. Subscribe to David’s free Astro-Space newsletter at www.davidreneke.com