You know how cop cars pile into each other in old comedy movies? That's how the Moon was built, say boffins

Moonlets glommed together


The birth of the Earth’s Moon didn’t begin with a single huge collision – rather it grew as lots of baby moons from smaller impacts fused together, according to a new theory published in Nature Geoscience.

Scientists believe that a proto-Earth and a Mars-sized body smashed together in the earlier days of the Solar System to create Earth’s only satellite. The leading theory, however, doesn’t explain why the Moon is mostly made up of Earth-like material, rather than a jumble of stuff from Earth and the other colliding body, called Theia.

Of course, the protoplanet that smacked into the young Earth could have had similar composition to our home world. Although that scenario is possible – some scientists suspect that Theia formed near Earth – researchers from the Weizmann Institute of Technology and the Technion–Israel Institute of Technology believe that the chances are slim.

That leaves the possibility that lots of relatively minor collisions between space rocks and Earth kicked up enough material to form baby moons that slammed into each other like the police in The Blues Brothers to create the Moon as we know it.

“Deriving more disk material from the proto-Earth occurs in impact scenarios with increased angular momentum beyond the present value, which is later dissipated by an orbital resonance or an associated limit cycle,” the paper [paywalled] said.

After a series of simulations modelling the collision, the impacts leave debris rings of Earth-like material instead of impactor material. Out of the 864 simulations ran, 750 resulted in debris disks with a “discernible mass.” The biggest disk was 1.2 times larger than the mass of the Moon.

The trail of debris grows with each impact to form something called a moonlet. Tidal forces from the Earth cause the moonlets to migrate outward to merge with a larger proto-Moon. It would take approximately 20 moonlet-forming impacts to make the Moon.

“Our model suggests that the ancient Earth once hosted a series of moons, each one formed from a different collision with the proto-Earth,” said Hagai Perets, coauthor and assistant professor at Technion.

Getting rid of the single giant-impactor event means that strict constraints on the debris disk mass and angular momentum can be released.

“Freedom in impact geometry and velocity allows mining more material from Earth, and the sum of such impact-generated moonlets may naturally lead to the current values of the Earth Moon system,” the paper noted. ®

Similar topics

Broader topics


Other stories you might like

  • SEC probes Musk for not properly disclosing Twitter stake
    Meanwhile, social network's board rejects resignation of one its directors

    America's financial watchdog is investigating whether Elon Musk adequately disclosed his purchase of Twitter shares last month, just as his bid to take over the social media company hangs in the balance. 

    A letter [PDF] from the SEC addressed to the tech billionaire said he "[did] not appear" to have filed the proper form detailing his 9.2 percent stake in Twitter "required 10 days from the date of acquisition," and asked him to provide more information. Musk's shares made him one of Twitter's largest shareholders. The letter is dated April 4, and was shared this week by the regulator.

    Musk quickly moved to try and buy the whole company outright in a deal initially worth over $44 billion. Musk sold a chunk of his shares in Tesla worth $8.4 billion and bagged another $7.14 billion from investors to help finance the $21 billion he promised to put forward for the deal. The remaining $25.5 billion bill was secured via debt financing by Morgan Stanley, Bank of America, Barclays, and others. But the takeover is not going smoothly.

    Continue reading
  • Cloud security unicorn cuts 20% of staff after raising $1.3b
    Time to play blame bingo: Markets? Profits? Too much growth? Russia? Space aliens?

    Cloud security company Lacework has laid off 20 percent of its employees, just months after two record-breaking funding rounds pushed its valuation to $8.3 billion.

    A spokesperson wouldn't confirm the total number of employees affected, though told The Register that the "widely speculated number on Twitter is a significant overestimate."

    The company, as of March, counted more than 1,000 employees, which would push the jobs lost above 200. And the widely reported number on Twitter is about 300 employees. The biz, based in Silicon Valley, was founded in 2015.

    Continue reading
  • Talos names eight deadly sins in widely used industrial software
    Entire swaths of gear relies on vulnerability-laden Open Automation Software (OAS)

    A researcher at Cisco's Talos threat intelligence team found eight vulnerabilities in the Open Automation Software (OAS) platform that, if exploited, could enable a bad actor to access a device and run code on a targeted system.

    The OAS platform is widely used by a range of industrial enterprises, essentially facilitating the transfer of data within an IT environment between hardware and software and playing a central role in organizations' industrial Internet of Things (IIoT) efforts. It touches a range of devices, including PLCs and OPCs and IoT devices, as well as custom applications and APIs, databases and edge systems.

    Companies like Volvo, General Dynamics, JBT Aerotech and wind-turbine maker AES are among the users of the OAS platform.

    Continue reading

Biting the hand that feeds IT © 1998–2022