News / Science & Technology

    Scientists Think Earth Once Had 2 Moons

    Full Moon as seen from Apollo 11 (1969)
    Full Moon as seen from Apollo 11 (1969)
    Jessica Berman

    A new theory by planetary scientists says the Earth may once have been orbited by two moons, which formed early in the history of the solar system and collided slowly into one another to form a single Moon.  

    Collision course

    Scientists believe the Moon was formed when a Mars-sized object crashed into Earth some 4.5 billion years ago and the debris accreted, or came together to form the Moon.

    But to Erik Asphaug a planetary scientist at the University of California Santa Cruz, that does not address what astronomers call the lunar dichotomy between the visible side of the moon, marked by craters and a thin crust, and the far side of the moon, known to contain a thicker crust and mountain ranges topping 3,000 meters.

    Using a computer model, Asphaug and Martin Jutzi of the University of Bern in Switzerland devised a scenario of what might have caused the geographic dichotomy between the visible and far sides of the Moon.  They believe it was caused by a slow-moving collision, less than 2.5 kilometers per second, by a nearby smaller moon.

    “It turns out when the impact that is striking the moon comes from right next door to the moon, it doesn’t have a lot of velocity - it’s a pretty slow collision," said Asphaug. "And by the time it hits the moon, it doesn’t have enough energy to excavate a big crater.  All it has the velocity to do is squash itself flat as a big pancake.  And that was a real surprising finding of the result, and when we saw that in the renderings of the computer simulations, we knew we were on to something pretty interesting.”

    The theory

    How did this collision between the two moons occur?  Scientists believe the smaller sister moon, made of the same rocky debris as the larger moon became stuck in the gravity between Earth and the bigger moon billions of years ago, drawing the smaller lunar object into an impact with the moon.

    Paul Spudis, a planetary scientist at the Lunar and Planetary Institute in Houston, Texas is withholding judgment on the theory.  

    “It’s an intriguing idea and like all new ideas, we need to evaluate it carefully," said Spudis. "But I think there are some issues with it.  And I’m not against it and I’m not for it.  I prefer just to remain skeptical at the moment.”

    Scientists believe the lunar dichotomy could be explained if they could compare mineral samples from the near and far sides of the moon.

    The US space agency NASA will next month launch the GRAIL or Gravity Recovery and Interior Laboratory mission that should help increase astronomers’ understanding of the moon.  GRAIL’s twin spacecraft will fly in tandem orbits around the moon, measuring its gravity fields.

    It is hoped the mission, which will analyze the moon’s crust through to its core, will help scientists better understand the formation of rocky planets in our solar system.

    An article on the possibility of two moons in Earth’s orbit is published in the journal Nature.

    You May Like

    Syrian Rebel Realignment Likely as al-Qaida Leader Blesses Split

    Jihadist group Jabhat al-Nusra splits from al-Qaida in what observers dub a ‘deception and denial’ exercise

    New India Child Labor Law Could Make Children More Vulnerable

    Concerns that allowing children to work in family enterprises will push more to work

    What Take-out Food Reveals About American History

    From fast-food restaurants to pizza delivery, the history of take-out food explains a lot about the changes taking place in society

    This forum has been closed.
    Comments
         
    There are no comments in this forum. Be first and add one

    Featured Videos

    Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
    Uganda Unveils its First Solar-powered Busi
    X
    July 28, 2016 4:16 AM
    A solar-powered bus described by its Ugandan makers as the first in Africa has made its public debut. Kiira Motors' electric bus, Kayoola, displayed recently at a stadium in Uganda's capital. From Kampala, Maurice Magorane filed this report narrated by Salem Solomon.
    Video

    Video Uganda Unveils its First Solar-powered Bus

    A solar-powered bus described by its Ugandan makers as the first in Africa has made its public debut. Kiira Motors' electric bus, Kayoola, displayed recently at a stadium in Uganda's capital. From Kampala, Maurice Magorane filed this report narrated by Salem Solomon.
    Video

    Video Silicon Valley: More Than A Place, It's a Culture

    Silicon Valley is a technology powerhouse and a place that companies such as Google, Facebook and Apple call home. It is a region in northern California that stretches from San Francisco to San Jose. But, more than that, it's known for its startup culture. VOA's Elizabeth Lee went inside one company to find out what it's like to work in a startup.
    Video

    Video Immigrant Delegate Marvels at Democratic Process

    It’s been a bitter and divisive election season – but first time Indian-American delegate Dr. Shashi Gupta headed to the Democratic National Convention with a sense of hope. VOA’s Katherine Gypson followed this immigrant with the love of U.S. politics all the way to Philadelphia.
    Video

    Video Philadelphia Uses DNC Spotlight to Profile Historic Role in Founding of United States

    The slogan of the Democratic National Convention now underway in Philadelphia is “Let’s Make History Again” which recognizes the role the city played in the foundation of the United States in the 18th century. As VOA’s Kane Farabaugh reports, local institutions are opening their doors in an effort to capitalize on the convention spotlight to draw visitors, and to offer more than just a history lesson.
    Video

    Video A Life of Fighting Back: Hillary Clinton Shatters Glass Ceiling

    Hillary Clinton made history Thursday, overcoming personal and political setbacks to become the first woman to win the presidential nomination of a major U.S. political party. If she wins in November, she will go from “first lady” to U.S. Senator from New York, to Secretary of State, to “Madam President.” Polls show Clinton is both beloved and despised. White House Correspondent Cindy Saine takes a look at the life of the woman both supporters and detractors agree is a fighter for the ages.
    Video

    Video Dutch Entrepreneurs Turn Rainwater Into Beer

    June has been recorded as one of the wettest months in more than a century in many parts of Europe. To a group of entrepreneurs in Amsterdam the rain came as a blessing, as they used the extra water to brew beer. Serginho Roosblad has more to the story.
    Video

    Video First Time Delegate’s First Day Frustrations

    With thousands of people filling the streets of Philadelphia, Pennsylvania for the 2016 Democratic National Convention, VOA’s Kane Farabaugh narrowed in on one delegate as she made her first trip to a national party convention. It was a day that was anything but routine for this United States military veteran.
    Video

    Video Commerce Thrives on US-Mexico Border

    At the Democratic Convention in Philadelphia this week, the party’s presumptive presidential nominee, Hillary Clinton, is expected to attack proposals made by her opponent, Republican presidential nominee Donald Trump, to build a wall along the U.S.-Mexico border. Last Friday, President Barack Obama hosted his Mexican counterpart, President Enrique Peña Nieto, to underscore the good relations between the two countries. VOA’s Greg Flakus reports from Tucson.
    Video

    Video Film Helps Save Ethiopian Children Thought to be Cursed

    'Omo Child' looks at effort of African man to stop killings of ‘mingi’ children
    Video

    Video London’s Financial Crown at Risk as Rivals Eye Brexit Opportunities

    By most measures, London rivals New York as the only true global financial center. But Britain’s vote to leave the European Union – so-called ‘Brexit’ – means the city could lose its right to sell services tariff-free across the bloc, risking its position as Europe’s financial headquarters. Already some banks have said they may shift operations to the mainland. Henry Ridgwell reports from London.
    Video

    Video Recycling Lifeline for Lebanon’s Last Glassblowers

    In a small Lebanese coastal town, one family is preserving a craft that stretches back millennia. The art of glass blowing was developed by Phoenicians in the region, and the Khalifehs say they are the only ones keeping the skill alive in Lebanon. But despite teaming up with an eco-entrepreneur and receiving an unexpected boost from the country’s recent trash crisis the future remains uncertain. John Owens reports from Sarafand.
    Video

    Video Migrants Continue to Risk Lives Crossing US Border from Mexico

    In his speech Thursday before the Republican National Convention, the party’s presidential candidate, Donald Trump, reiterated his proposal to build a wall along the U.S.-Mexico border if elected. Polls show a large percentage of Americans support better control of the nation's southwestern border, but as VOA’s Greg Flakus reports from the border town of Nogales in the Mexican state of Sonora, the situation faced by people trying to cross the border is already daunting.

    Special Report

    Adrift The Invisible African Diaspora