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Skywatchers have been trying to gauge the sun-Earth distance for thousands of years. In the third century BC, Aristarchus of Samos, notable as the first to argue for a heliocentric solar system, estimated the sun to be 20 times farther away than the moon. It wasn't his best work, as the real factor is more like 400. By the late 20th century, astronomers had a much better grip on this fundamental cosmic metric -- what came to be called the astronomical unit. In fact, thanks to radar beams pinging off various solar-system bodies and to tracking of interplanetary spacecraft, the...

University of Arizona scientists have uncovered a curious case of missing asteroids. The main asteroid belt is a zone containing millions of rocky objects between the orbits of Mars and Jupiter. The scientists find that there ought to be more asteroids there than researchers observe. The missing asteroids may be evidence of an event that took place about 4 billion years ago, when the solar system's giant planets migrated to their present locations. UA planetary sciences graduate student David A. Minton and UA planetary sciences professor Renu Malhotra say missing asteroids is an important piece of evidence to support an...

Evidence that water came to Earth during its formation from cosmic dust, rather than following later in asteroids, has been shown by a group of international scientists. The origin of the abundant levels of water on Earth has long been debated with the main differences in the theories being the nature of the material that carries the water, and whether the water came during or after planet formation. Now, Nora de Leeuw at University College London, UK, and colleagues have used molecular-level calculations to prove that dissociative chemisorption of water onto the surface of olivine rich minerals, such as forsterite,...

You can't breathe on the moon, but now you can smell it. A Scottish printmaker has released a series of works that publicize a fact known to astronauts for decades: The moon smells like gunpowder. Apprentice printer Sue Corke worked with flavorist Steven Pearce of Omega Ingredients and Apollo 16 astronaut Charles M. Duke Jr. to create "scratch-and-sniff" moon prints. NASA has known since the 1970s about the gunpowder-like odor of Earth's natural satellite. Even though there's no air on the moon, one moonwalker, Apollo 14 lunar module pilot Edgar D. Mitchell, confirmed to AOL News that the moon smells...

An analysis of sediments brought back by the Apollo 17 mission has shown that the Moon's interior holds far more water than previously thought.The analysis, reported in Science, has looked at pockets of volcanic material locked within tiny glass beads. It found 100 times more water in the beads than has been measured before, and suggests that the Moon once held a Caribbean Sea-sized volume of water. The find also casts doubt on aspects of theories of how the Moon first formed. A series of studies in recent years has only served to increase the amount of water thought to...

Early in the evening of June 18, 1178, a group of men near Canterbury, England, stood admiring the sliver of a new moon hanging low in the west. In terms they later described to a monk who recorded their sighting, "Suddenly a flaming torch sprang from the moon, spewing fire, hot coals and sparks." In continuing their description of the event, they reported that "The moon writhed like a wounded snake and finally took on a blackish appearance"... [P]lanetary scientist Jack Hartung of the State University of New York... gathered enough clues to suggest that a large asteroid... might have...

STEREO Hunts for Remains of an Ancient Planet near Earth April 9, 2009: NASA's twin STEREO probes are entering a mysterious region of space to look for remains of an ancient planet which once orbited the Sun not far from Earth. If they find anything, it could solve a major puzzle--the origin of the Moon. The name of the planet is Theia," says Mike Kaiser, STEREO project scientist at the Goddard Space Flight Center. "It's a hypothetical world. We've never actually seen it, but some researchers believe it existed 4.5 billion years ago—and that it collided with Earth to form...

Clara Moskowitz The solar system might once have had another planet named Theia, which may have helped create our own planet's moon. Now two spacecrafts are heading out to search for leftovers from this rumored sibling, which would have been destroyed when the solar system was still young. "It's a hypothetical world. We've never actually seen it, but some researchers believe it existed 4.5 billion years ago — and that it collided with Earth to form the moon," said Mike Kaiser, a NASA scientist at the Goddard Space Flight Center in Maryland...

April 9, 2009: NASA's twin STEREO probes are entering a mysterious region of space to look for remains of an ancient planet which once orbited the Sun not far from Earth. If they find anything, it could solve a major puzzle--the origin of the Moon. "The name of the planet is Theia," says Mike Kaiser, STEREO project scientist at the Goddard Space Flight Center. "It's a hypothetical world. We've never actually seen it, but some researchers believe it existed 4.5 billion years ago—and that it collided with Earth to form the Moon." Right: An artist's concept of one of the...

Line up Mercury, Venus, Earth and Mars according to their distance from the sun and you'll see their size distribution is close to symmetrical, with the two largest planets between the two smallest. That would be no coincidence -- if the pattern emerged from a debris ring around the sun. Brad Hansen of the University of California, Los Angeles, built a numerical simulation to explore how a ring of rocky material in the early solar system could have evolved into the planets. He found that two larger planets typically form near the inner and outer edges of the ring, corresponding...

Neptune's largest moon, Triton, was originally a member of a duo orbiting the Sun but was kidnapped during a close encounter with Neptune, a new model suggests. Triton is unique among large moons in that it orbits Neptune in a direction opposite to the planet's rotation, which long ago led scientists to speculate that the moon originally orbited the Sun. But until now, no convincing theory for how Triton paired with Neptune existed. Gravity might have pulled Triton away from its companion to make it an orbiting satellite of Neptune, researchers report in a new study published in the May...

Speranza points out another difficulty with the impact-origins theory. Large blocks of limestone sit within the boundaries of the Sirente "crater." Such limestone would not have survived an impact. So if Ormö's theory is correct, one must surmise that somebody set these giant chunks of rock in place since the crater formed. To Speranza, that just didn't make sense. Speranza and colleagues further argue that Ormö's radiocarbon dating gave one age for the main feature (placing it in the 4th or 5th century a.d.) and a completely different age for a nearby "crater" called C9, a date in the 3rd...

Deep down, the moon may be more like Earth than scientists ever thought. A new moon-rock study suggests the satellite has an iron core... The moon's core could be a clue to its ancient origins, which have long puzzled astronomers. "Our moon is too big to be a moon," Taylor said. "It's huge compared to the moons we see around other planets, so it has always been suspected that there was something strange in its origin." ...Rock samples from NASA's Apollo 15 and Apollo 17 moon missions of the early 1970s have now shed more light on the moon's origins,...

The crash may also someday create the biggest and brightest comet of all time. Astronomer Michael Brown of the California Institute of Technology found the five fragments while studying the Kuiper belt, located in the solar system's outermost reaches. The fragments resemble 2003 EL61, the Kuiper belt's mysterious third largest object, suggesting all six bodies were formed in a single violent crash, Brown said... Measuring about 930 miles (1,500 kilometers) across, 2003 EL61 had puzzled scientists ever since its discovery, because it's oblong and spins end-over-end so fast that it completes a full revolution every four hours... 2003 EL61 is...

A tiny 4.4-billion-year-old crystal has been confirmed as the oldest fragment of Earth's crust. The zircon was found in sandstone in the Jack Hills region of Western Australia. Scientists dated the crystal by studying its uranium and lead atoms. The former decays into the latter very slowly over time and can be used like a clock. The finding has been reported in the journal Nature Geoscience. Its implication is that Earth had formed a solid crust much sooner after its formation 4.6 billion years ago than was previously thought, and very quickly following the great collision with a Mars-sized body...

Daniel Saat, business development manager for SpaceIL, is reasonably confident that the lunar lander the Israeli spaceship organization is working on will beat out the competition and reach the moon, winning the big $30 million prize being offered by Google in its LunarX challenge. “Our intelligence sources tell us that Israel’s LunarX satellite is one of the two or three top contenders to win this contest,” Saat told The Times of Israel on Sunday. And he’s also pretty certain the 140 kilogram spacecraft will actually land safely on the moon and perform the stunts Google requires to award the prize...

Are you ready for some lunar versus planetary occultation action? One of the best events for 2014 occurs early this Wednesday morning on February 26th, when the waning crescent Moon — sometimes referred to as a decrescent Moon — meets up with a brilliant Venus in the dawn sky. This will be a showcase event for the ongoing 2014 dawn apparition of Venus that we wrote about recently. This is one of 16 occultations of a planet by our Moon for 2014, which will hide every naked eye classical planet except Jupiter and only one of two involving Venus this...

Landing on the moon is no easy feat, and five teams competing for the $30 million Google Lunar X Prize might just get a little more money to help them send their probes to the lunar surface. Astrobiotic, Moon Express, Team Indus, Hakuto and Part-Time-Scientists are all in the running to win "milestone prizes" later this year, Google Lunar X Prize officials announced today (Feb. 19). The total purse for the awards is $6 million with the teams competing in three different categories for the funds, X Prize officials said. Each company's ultimate goal is to ready its probe for...

Want this article to load more quickly? Read it in space. Hong Kong has the world's fastest Internet. Internet on the moon is 10 times faster. How do our lunar-exploring spaceships get buffer-free video? Lasers. NASA and MIT are shooting "lasers full of Internet" to a ship named LADEE that's exploring the moon's atmosphere. According to NASA, speeds have reached 622 megabits per second (Hong Kong tops out at 63.6). Right now, the agency is using a pulsed laser beam to transmit a pair of HD video signals to and from the moon. The 239,000 miles between the New Mexico...

The private spaceflight company Space X plans to build a rocket so big it would "make the Apollo moon rocket look small,"the company's CEO, Elon Musk, announced on "CBS This Morning"on Feb. 3. The huge rocket would ultimately send colonists to Mars, but what would SpaceX do in the meantime? The company's primary focus right now is giving NASA astronauts access to the International Space Station (ISS) on American vehicles, drastically lowering prices to Earth orbit versus what the Russians are charging, Musk said... This all begs the question: If SpaceX is going to build this gargantuan rocket on its...