Earth must have felt pretty inadequate a week or two ago when astronomers announced that distant Pluto has yet another moon. Pluto! Recently demoted to a dwarf planet! And yet it boosted its satellite total to four, while we remain forever stuck at one. True, Earth is ahead of Mercury and Venus, which have no moons at all. But Mars, which is significantly smaller than Earth, has two; and don’t even mention Jupiter, with more than 60; or Saturn, with 53. Even asteroids have multiple moons — including Sylvia, a 384-mile (617 km) space rock that boasts the twin satellites Romulus and Remus.
But Earth’s rep may might gotten a bump, thanks to a paper just published in the journal Nature. Our home planet may have just one lonely moon now, but long ago, like Mars and Sylvia, we had two. "Whether it’s right or not, I don’t know," says Maria Zuber, a planetary scientist at MIT who wrote an opinion piece accompanying the new study. "But I think it’s very plausible."
This diagram provided by Martin Jutzi and Erik Asphaug, University of California, Santa Cruz via Nature shows a simulation of four stages of a collision between the Moon and a companion moon, four percent of the lunar mass, about 4 billion years ago. Earth once had a second moon, until it made the fatal mistake of smacking its big sister, some astronomers now theorize. For awhile when the Earth was young, it had a big moon, the one you see now, and a smaller "companion moon" orbiting above. Then one day that smaller moon collided into the bigger one in what astronomers are calling the "big splat." (AP Photo/Martin Jutzi and Erik Asphaug, University of California, Santa Cruz via Nature)
The idea, cooked up by astronomers Martin Jutzi and Erik Asphaug, of the University of California at Santa Cruz, started out as an attempt to explain why our moon has so asymmetrical a surface. The part that faces us is relatively smooth, with vast expanses of ancient lava forming flat, dark, low-lying plains that earlier astronomers mistook for oceans. But when space probes first circled the moon in the early 1960s, scientists learned that the far side is mostly covered with rugged mountains and craters.
This artist’s rendering provided by Martin Jutzi and Erik Asphaug, University of California, Santa Cruz via Nature shows a simulation of a collision between the Moon and a companion moon, four percent of the lunar mass, about 4 billion years ago. Earth once had a second moon, until it made the fatal mistake of smacking its big sister, some astronomers now theorize. For awhile when the Earth was young, it had a big moon, the one you see now, and a smaller "companion moon" orbiting above. Then one day that smaller moon collided into the bigger one in what astronomers are calling the "big splat." (AP Photo/Martin Jutzi and Erik Asphaug, University of California, Santa Cruz via Nature)
Nobody has ever been able to explain with certainty why the moon should be so lopsided: maybe it had to do with some kind of massive impact that violently rearranged the surface, much like what happened to the asteroid Vesta. Maybe it was a slightly off-center core that caused the crust to be thinner on the Earth-facing half of the moon, which made that hemisphere more susceptible to lava bleeds.
But then Jutzi and Asphaug began thinking. "It looked to us a little bit as though the highlands on the far side accreted" — which is to say, they were added on top of the pre-existing surface. The astronomers thought a bit more, and realized that this idea was consistent with scientists’ beliefs about how the moon formed in the first place. Thanks to the analysis of moon rocks that were brought back by the Apollo missions, planetary scientists are pretty sure that our satellite was born billions of years ago when a Mars-size planetoid smashed into the young Earth.
The impact blasted off a cloud of debris from both of the objects and sent it spinning into space, where it eventually congealed into the moon. There could have been other, smaller pieces as well, says Zuber, but their orbits would have been unstable, causing them either to be flung away or to fall into Earth or the moon pretty much immediately.
Except, that is, if they happened to end up at a Trojan point — a place in the same orbit as the moon, but either well ahead of or well behind it, that’s gravitationally stable — or relatively so anyway. Just last week, astronomers announced the discovery of a Trojan asteroid leading the planet Earth around the sun. There’s no reason a Trojan moon couldn’t lead or follow our moon around the Earth.
Trojan Asteroid: Like a poodle on a leash, tiny asteroid runs ahead of Earth in orbit of sun
By Malcolm Ritter | YahooNews.ca / AP
Like a poodle on a leash, a tiny asteroid runs ahead of Earth on the planet’s yearlong strolls around the sun, scientists report.
The discovery of this companion, which measures only about 300 metres across, makes Earth the fourth planet in the solar system that’s known to share its orbit with an asteroid.
Imagine Earth and the asteroid travelling around a clock face, with the sun in the middle. Generally, the asteroid runs about two numbers ahead.
However, the asteroid sometimes ranges so far ahead that it’s on the opposite side of the sun from Earth, said Martin Connors of Canada’s Athabasca University in Alberta. He reports the work with colleagues in Thursday’s issue of the journal Nature.
Asteroids are giant space rocks that orbit the sun, and ones that share an orbit with a planet are called Trojans. Scientists had previously found a few for Mars and Neptune and nearly 5,000 for Jupiter. Spotting one in Earth’s orbit is difficult from the ground because the potential locations are generally in the daytime sky.
The newfound object, called 2010 TK7, was discovered last year by NASA’s WISE satellite. Connors and colleagues were able to focus a ground-based telescope in Hawaii on it in April, determining its orbit with enough precision to show it was a Trojan.
Donald K. Yeomans, manager of NASA’s Near-Earth Object Program Office, who didn’t participate in the discovery, agreed that the asteroid is a Trojan. Most scientists suspected Earth had them, he said, and "I would guess there’s others."
Former Chief Security Officer for NewsCorp: N. Koreans Not Behind Sony Hack, Interview Leak 2014-12-20 2:17
Hemanshu Nigam, a former federal prosecutor and former chief security officer for NewsCorp/Fox studios, says North Korea isn’t behind the Sony Hack.
Nigam gave several bullet points for why the hack was likely an inside job.
Attack code borrowed from a previous attack on Seoul, that’s why it’s in Korean. Private hackers typically borrow malicious code from other hackers.Nations state attacks follow ...
Sony Fires Back at Obama: Actually We Did Call the White House – Several Times 2014-12-20 2:13 Sony fired back at Obama after the press conference saying they had several conversations with the Obama White House before and after the movie was canceled.
Via The Hollywood Reporter:
After President Obama criticized Sony for its decision to cancel The Interview's release after theater chains decided not to show the film, the studio has issued a statement elaborating on the move.
The Bankster International 2014-12-20 1:55 Geopolitical analysis, the art of explaining power relationships through the prism of impersonal geography, can be a helpful tool for observers of the Great Game – but it also has its limitations. A case in point is the renewed US-Russia confrontation. Think tanks and policy insiders easily sell the narrative that from the dark days of the Cold War to ...
Another banker dies under suspicious circumstances 2014-12-20 1:09 52-year-old Belgian Geert Tack – a private banker for ING who managed portfolios for wealthy individuals – was described as ‘impeccable’, ‘sporty’, ‘cared-for’, and ‘successful’ and so as Vermist reports, after disappearing a month ago, the appearance of his body off the coast of Ostend is surrounded by riddles…
Impeccable. Sporty. Cared for. Successful. Just some qualifications that are attributed to ...
NATO increases military presence on Russia’s borders 2014-12-20 1:14
The Pentagon has confirmed the military buildup along Russia’s borders to ensure long-term “peace and stability” in the region.
Earlier Moscow accused NATO of a sharp increase in air activity and intelligence flights in the border zone.
Replying to RIA Novosti’s query on the increased number of NATO flights around Russia’s borders, a Pentagon representative told the news agency that the military ...