Hello,

We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not a subscriber? Subscribe now for unlimited access to online articles.

Emerging Technology from the arXiv

A View from Emerging Technology from the arXiv

Lunar Crater Stats Indicate Hidden Population of Asteroids

The asymmetric distribution of craters on the Moon may have been caused by an undiscovered population of near Earth asteroids

  • August 3, 2009

Many moons are locked in synchronous rotation with their mother planets. Examples include the Galilean moons of Jupiter, Neptune’s moon Triton and our own Moon.

In the 80s and 90s astronomers noticed that the distribution of craters on these objects was asymmetric: they were more heavily cratered on their leading hemispheres which makes sense since it seems obvious that these areas should be struck more often.

It wasn’t until 2003, however, that the same asymmetric crater distribution was measured on our Moon. Now Takashi Ito at the National Astronomical Observatory in Japan and Renu Malhotra at the University of Arizona have asked an interesting question. of the data. Can the asymmetric distribution of craters on the Moon be explained by the known distribution of near Earth asteroids that are thought to have caused them? Their answer is a cautious “no”.

To properly explain the crater distribution, Ito and Malhotra say some other factor must have been involved. One possibility is that we simply haven’t seen all the craters yet: the ongoing lunar mapping missions may help on that score.

Another idea is that the Earth’s tidal forces tear Earth-crossing asteroids apart, creating a higher number of impacts than might otherwise be expected.

But the most exciting and potentially worrying possibility is that there exists a previously unseen population of near Earth asteroids that orbit the Sun at approximately the same distance as the Earth. These have gone unnoticed because they are smaller or darker than other asteroids, say Ito and Malhotra.

“More complete observational surveys of the near-Earth asteroids can test our prediction,” they say.

And let’s not waste too much time about it. By some reckonings, asteroid impacts represent the greatest threat to humankind that we are able to calculate.

Ref: arxiv.org/abs/0907.3010: Asymmetric Impacts of Near-Earth Asteroids on The Moon

Become an MIT Technology Review Insider for in-depth analysis and unparalleled perspective.

Subscribe today
Want more award-winning journalism? Subscribe to Print + All Access Digital.
  • Print + All Access Digital {! insider.prices.print_digital !}*

    {! insider.display.menuOptionsLabel !}

    The best of MIT Technology Review in print and online, plus unlimited access to our online archive, an ad-free web experience, discounts to MIT Technology Review events, and The Download delivered to your email in-box each weekday.

    See details+

    12-month subscription

    Unlimited access to all our daily online news and feature stories

    6 bi-monthly issues of print + digital magazine

    10% discount to MIT Technology Review events

    Access to entire PDF magazine archive dating back to 1899

    Ad-free website experience

    The Download: newsletter delivered daily

/3
You've read of three free articles this month. for unlimited online access. You've read of three free articles this month. for unlimited online access. This is your last free article this month. for unlimited online access. You've read all your free articles this month. for unlimited online access. You've read of three free articles this month. for more, or for unlimited online access. for two more free articles, or for unlimited online access.