Study shows proportionally large moons around other planets not as rare as thought

Jun 06, 2011 by Bob Yirka report
The image of the moon is courtesy of NASA.

( -- Working with computer simulations to recreate what scientists believe to be the conditions that led to the formation of Earth’s moon, which up to now has been considered quite large, a team of researchers from Switzerland and the United States, in a paper published on arXiv, have shown the likelihood of other planets having proportionally large moons is much higher than was previously thought.

Earth’s moon is believed to have come into existence as a result of a collision with another planet, causing massive amounts of debris to be knocked into orbit, and over time coalescing into the single round entity we know and love today. Such an occurrence has generally been thought to be a rare event though, and as such, most scientists have believed that the proportional size of our moon, to Earth, was much larger than that found with most other moons orbiting other rocky .

Tossing that notion on its head, the new simulations indicate that the odds of such an occurrence range from 1 in 6, to 1 in 45, which in either case, would mean a lot more planet/moon pairs out there are much closer in size than most anyone thought. The reason this is important is because a large such as the one circling our planet tends to stabilize the tilt of the planet which in turn helps stabilize heat the distribution from sun, making life much more possible. This is good news for those spending their careers tying to find such planets, insomuch as it makes the probability of their being other planets out there supporting some form of life form, much more likely; but not so good is that it means there are likely far more planets that must now be sifted through.

The simulations were based on the way that planets are believed to form from smaller bits of rock called planetesimals and gas and were run using data previously obtained from simulations run on systems that very closely related those with Earth-like planet systems.

Not everyone is ready to jump on board with the new results however; some such as Eiichiro Kokubo, an authority on planet formation, while speaking to the BBC, cautioned that there are still too many variables in the equations used in the simulated results to draw any definite conclusions, and thus believes more research must be done before accepting the new conclusions as truth.

Explore further: Precise ages of largest number of stars hosting planets ever measured

More information: How common are Earth-Moon planetary systems? arXiv:1105.4616v1 [astro-ph.EP]

The Earth's comparatively massive moon, formed via a giant impact on the proto-Earth, has played an important role in the development of life on our planet, both in the history and strength of the ocean tides and in stabilizing the chaotic spin of our planet. Here we show that massive moons orbiting terrestrial planets are not rare. A large set of simulations by Morishima et al., 2010, where Earth-like planets in the habitable zone form, provides the raw simulation data for our study. We use limits on the collision parameters that may guarantee the formation of a circumplanetary disk after a protoplanet collision that could form a satellite and study the collision history and the long term evolution of the satellites qualitatively. In addition, we estimate and quantify the uncertainties in each step of our study. We find that giant impacts with the required energy and orbital parameters for producing a binary planetary system do occur with more than 1 in 12 terrestrial planets hosting a massive moon, with a low-end estimate of 1 in 45 and a high-end estimate of 1 in 4.

Related Stories

'Hot Jupiter' planets unlikely to have moons

Aug 23, 2010

( -- Planets of the major type so far found outside our solar system are unlikely to have moons, according to new research reported in the August 20 issue of The Astrophysical Journal Letters.

Wobbly planets could reveal Earth-like moons

Dec 11, 2008

Moons outside our Solar System with the potential to support life have just become much easier to detect, thanks to research by an astronomer at University College London (UCL).

Earth-like planets may be found soon

Mar 24, 2008

U.S. experts say known planets outside of Earth's solar system, currently numbered at 277, could soon include smaller planets that are closer to Earth's size.

The Earth and Moon formed later than previously thought

Jun 07, 2010

The Earth and Moon were created as the result of a giant collision between two planets the size of Mars and Venus. Until now it was thought to have happened when the solar system was 30 million years old or ...

Planetary systems can form around binary stars

Jan 10, 2006

New theoretical work shows that gas-giant planet formation can occur around binary stars in much the same way that it occurs around single stars like the Sun. The work is presented today by Dr. Alan Boss of ...

Avatar's moon Pandora could be real

Dec 17, 2009

In the new blockbuster Avatar, humans visit the habitable - and inhabited - alien moon called Pandora. Life-bearing moons like Pandora or the Star Wars forest moon of Endor are a staple of science fiction. ...

Recommended for you

What is the habitable zone?

9 hours ago

The weather in your hometown is downright uninhabitable. There's scorching heatwaves, annual tyhpoonic deluges, and snow deep enough to bury a corn silo.

Galaxy survey to probe why the universe is accelerating

9 hours ago

We know that our universe is expanding at an accelerating rate, but what causes this growth remains a mystery. The most likely explanation is that a strange force dubbed "dark energy" is driving it. Now a ...

High resolution far-infrared all-sky image data release

11 hours ago

A research group led by a University of Tokyo researcher, using the AKARI satellite's Far-Infrared All-Sky data, have created all-sky image maps and released the full database to researchers around the world ...

The discovery of the molecule Si-C-Si in space

Jun 29, 2015

The space between stars is not empty—it contains a vast reservoir of diffuse material with about 5-10% of the total mass of our Milky Way galaxy. Most of the material is gas, but about 1% of this mass (quite ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.