THE NEW HORIZONS PLUTO MISSION IS A BIG DEAL. HERE ARE SOME REASONS WHY

SOURCE : vox.com 

NASA’s New Horizons spacecraft is about to show us an alien world for the first time. At precisely 7:49 am ET on Tuesday, the probe will become the first spacecraft to fly by Pluto.

New Horizons has been en route for nine years, traveling more than 3 billion miles. The flyby will be over in a matter of minutes, as the probe frantically takes hundreds of photos and collects data on Pluto’s atmosphere, geology, and moons. All this data will be enormously valuable to scientists as they seek to understand our solar system and how it formed billions of years ago.

More than anything, this mission is about broadening our horizons — taking in just a little bit more of the impossibly vast universe we live in.

1) We’ve never seen Pluto before

Pluto feels familiar. It’s easy to imagine the small, frigid rock, millions of miles from the sun and covered in ice.

But what you’re picturing in your head when you think about Pluto is probably an artist’s illustration. Until very recently, we didn’t even know exactly what color it was — and the best photos we had of Pluto looked like this:

New Horizons is going to change that in a very big way. Already, as it’s closed in on Pluto, it’s given us way better photos than ever before:

Pluto (right) and its moon Charon, as seen by New Horizons on July 11. (NASA-JHUAPL-SWRI)

The high-resolution photos to come will give us detailed topographical maps, just like those provided by the satellites that orbit Earth. They could reveal mountains, ice caps, volcanoes, or even an ocean of liquid water under the ice. “Who knows what kind of bizarre things we’ll find up close?” Stern said.

2) This mission will remind you how vast space really is

Earth, as seen by the Voyager spacecraft, from more than 4 billion miles away.

We spend our entire lives on the surface of Earth — so it’s hard to really grasp how far away Pluto truly is from us.

But as an analogy, think of Earth as a basketball. By comparison, Pluto would be a little larger than a golf ball. But if you wanted to keep the scale constant, you’d have to put that golf ball incredibly far away: 50 to 80 miles (depending on its location in orbit). This mission, like many activities in space, is a good reminder of how vast our corner of the universe is — and how absurdly tiny our entire earthly realm of experience is by comparison.

And it’s not just the size of space that boggles the mind. It’s also the timescale on which everything occurs. Pluto takes 248 Earth years to orbit the sun. To put it another way, the entirety of US history has occurred during a single Plutonian orbit.

3) We won’t get many more missions like this for a while

There’s a mission to Europa planned, but it won’t reach the moon for a decade or more.

The past few decades have been filled with all sorts of fascinating missions to the planets, moons, asteroids, and comets of our solar system — uncrewed probes sent every few years, run by trained scientists, and supported by government funding.

But the sad truth is that this era is largely drawing to a close. As David W. Brown writes in an article on the dark future of American space exploration, “There is nothing budgeted in the pipeline to take its place. Yesterday invested in today. But we are not investing in tomorrow.”

This is the result of cutbacks to NASA’s planetary exploration budget. The OSIRIS-REx probe will launch next year, to travel to an asteroid and bring back a sample, but it won’t return until 2023. Meanwhile, a mission to Jupiter’s moon Europa is in the works, but it likely won’t be launched until 2025 at the earliest, and wouldn’t reach Europa until the 2030s.

In other words: Enjoy this brief flyby. It’s going to be a while before any NASA probe visits a new world.

4)This is a staggering technological achievement

t’s hard to appreciate just how difficult it is to send a spacecraft to Pluto. But think of it this way: because it’s so incredibly far away, it took New Horizons nine years to cover the 3-billion-mile trip there — which means the craft is using decade-old technology, traveling a route that was calculated years ago.

New Horizons’ trajectory through the solar system.

Despite this, NASA engineers managed to get the tiny probe — about the size and shape of a grand piano — to an incredibly precise spot in space, using Jupiter’s gravity as a slingshot to accelerate it outward and a few thruster burns over the years to keep the probe on track.

Along the way, they had to worry about potentially damaging debris nearby Pluto — as well as a scary software glitch this past weekend, which was, thankfully, resolved. Now New Horizons is going to fly within 7,750 miles of Pluto, coming closer than its moons.

Because New Horizons is traveling at such a high speed (about 31,000 miles per hour) and can’t slow down, the flyby will be over in a matter of minutes — fording it to collect all its data in a tiny window of time.

And receiving all that data is another huge challenge. Because New Horizons is so far away, it takes about 4.5 hours for any data it sends back to reach Earth. And the signal is so faint that NASA has to use 200-foot-wide radio dishes (one each in Australia, California, and Spain) to pick it up. This means an extremely low rate of data transmission: about 1 kilobit per second, more than 50 times slower than a 56k modem from the ’90s. It takes more than 42 minutes for New Horizons to fully transmit an image that’s 1024 pixels wide.

If you haven’t been paying attention so far, now’s the time to start. This is a really big deal.

NASA to Send Microsoft's Virtual Reality Headset to International Space Station

NASA is sending Microsoft's virtual reality headset to the International Space Station (ISS) to beam back to Earth what astronauts see in space.

NASA and Microsoft are teaming up to develop Sidekick, a new project using commercial technology to empower astronauts aboard the ISS.

Sidekick uses Microsoft HoloLens to provide virtual aid to astronauts working off the Earth.

A pair of the devices is scheduled to launch on SpaceX's seventh commercial resupply mission to the station on June 28.

"HoloLens and other virtual and mixed reality devices are cutting edge technologies that could help drive future exploration and provide new capabilities to the men and women conducting critical science on the International Space Station," said Sam Scimemi, director of the ISS programme at NASA Headquarters in Washington.

"This new technology could also empower future explorers requiring greater autonomy on the journey to Mars," said Mr Scimemi.

The goal of Sidekick is to enable station crews with assistance when and where they need it. This new capability could reduce crew training requirements and increase the efficiency at which astronauts can work in space.

"Sidekick is a prime example of an application for which we envisioned HoloLens being used - unlocking new potential for astronauts and giving us all a new perspective on what is possible with holographic computing," said Alex Kipman, technical fellow, Windows and Devices Group at Microsoft.

NASA and Microsoft engineers tested Project Sidekick and the Microsoft HoloLens aboard NASA's Weightless Wonder C9 jet to ensure they function as expected in free-fall in advance of their delivery to the microgravity environment of the space station.

Sidekick has two modes of operation. The first is "Remote Expert Mode," which uses Skype to allow a ground operator to see what a crew member sees, provide real-time guidance, and draw annotations into the crew member's environment to coach him or her through a task.

Until now, crew members have relied on written and voice instructions when performing complex repair tasks or experiments.

The second mode is "Procedure Mode," which augments standalone procedures with animated holographic illustrations displayed on top of the objects with which the crew is interacting.

This capability could lessen the amount of training that future crews will require and could be an invaluable resource for missions deep into our solar system, where communication delays complicate difficult operations.

Source : NDTV

[Video] Nasa revealed Far side of moon

A number of people asked what the other side of the Moon looks like, the side that can't be seen from the Earth. This video answers that question. The imagery was created using Lunar Reconnaissance Orbiter data.

https://www.youtube.com/watch?v=cDHLdXu5JvI&feature=youtu.be

Source : NASA

Researchers: Solar system may have Planet X , Planet Y

The presence of two additional planets might explain the unexpected orbital features of some trans-Neptunian objects.

Scientists have postulated the existence of possibly two undiscovered planets beyond the orbit of Neptune to explain discrepancies in the orbits of extreme trans-Neptunian objects (ETNO). The objects have orbits that take them beyond the orbit of the planet Neptune.

Theory predicts that they be randomly distributed and that their orbits must have a semi-major axis with a value around 150 AU; an orbital inclination of nearly zero degrees; and an angle of perihelion, the point in the object’s orbit at which it is closest to the Sun, of zero to 180 degrees.

However, a dozen ETNO do not fit these orbital criteria. These objects have semi-major axis values of 150 to 525 AU, orbital inclinations of around 20 degrees, and angles of perihelion far from 180 degrees.

According to a statement, a new study by astrophysicists at the Complutense University of Madrid (UCM) and University of Cambridge have calculated that these orbital discrepancies could be explained by the existence of at least two additional planets beyond the orbits of Neptune and dwarf planet Pluto. Their study suggests that the gravitational pulls of those two planets must be disturbing the orbits of some smaller ETNO.

However, there are two difficulties with the hypothesis. One is that current models of the formation of our solar system do not allow for additional planets beyond Neptune. Secondly, the team’s sample size is very small, only 13 objects. However, additional results are in the pipeline, which will expand the sample.

“This excess of objects with unexpected orbital parameters makes us believe that some invisible forces are altering the distribution of the orbital elements of the ETNO and we consider that the most probable explanation is that other unknown planets exist beyond Neptune and Pluto,” said Carlos de la Fuente Marcos of UCM and lead author on the study.

The new findings have been published in two papers published in the journal Monthly Notices of the Royal Astronomical Society Letters.

Source : thespacereporter

SpaceX will launch micro-satellites for low cost internet

Follow us on Google+ , Twitter and Facebook



Elon Musk has confirmed that SpaceX is working on micro-satellites. Following a story in The Wall Street Journal, he tweeted this morning that SpaceX is developing “advanced micro-satellites operating in large formations” with an official announcement due in two to three months.

It said SpaceX is planning a launch of 700 satellites, each weighing less than 250 pounds. A fleet that size would be 10x bigger than the largest current deployment managed by  Iridium Communications.

Sorce : next web

ISS crew lands, brings space-born flies to Earth

Follow us on Google+ , Twitter and Facebook



Three crew members of the International Space Station have safely returned to Earth aboard a Soyuz-13M spacecraft, bringing back good memories and results of their 165-day shift in orbit – including a space-born generation of experimental fruit flies.

The spacecraft carrying the commander of the ISS Expedition 41 Russian cosmonaut Maksim Surayev, as well as two flight engineers, NASA astronaut Reid Wiseman and ESA astronaut Alexander Gerst, landed some 80 km from Arkalyk, Kazakhstan.

As part of their mission, the crew completed some 2,640 orbits covering more than 70 million miles and have participated in a number of experiments, including breeding of fruit flies that could potentially shed light on long-term space flight effects on human beings.

China probe flies around moon and back in first such mission since 1970s

Follow us on Google+ , Twitter and Facebook




Chinese researchers examine the scorched Chang’e 5-T1 return capsule after it landed successfully in Inner Mongolia having travelled around the moon and back.

Photograph: Xinhua

China has completed its first return mission to the moon with the successful re-entry and landing on Earth of an unmanned probe, state media reported.

The probe, Chang’e 5-T1, landed safely in northern China’s Inner Mongolia region, state news agency Xinhua said, citing the Beijing Aerospace Control Centre.

Xinhua said the probe, dubbed “Xiaofei” (little flyer) on social media, took “some incredible pictures” of the Earth and the moon. It is the first trip around the moon and back since US and Russian flights of the 1970s, 40 years ago.

Prior to re-entering the Earth’s atmosphere the unnamed probe had been travelling at 11.2 kilometres per second (25,000 miles per hour), a speed that can generate temperatures of more than 1,500C (2,700F), the news agency reported.

To slow it down scientists let the craft “bounce” off Earth’s atmosphere before re-entering again and landing.

The probe’s mission was to travel to the moon, fly around it and head back to Earth, said the the state science and technology agency, Sastind. The module went 413,000km from Earth at its furthest point.

The mission was launched to test technology to be used in the Chang’e-5, China’s fourth lunar probe, which aims to gather and return samples from the surface in 2017.

The military-run space project has plans for a permanent orbiting station by 2020 and eventually to send a human to the moon.

China currently has a robotic rover, Yutu (Jade Rabbit), on the moon. It landed on 14 December 2013 and completed parts of its mission before grinding to a halt on 25 January 2014 due to equipment failure.

Source : The Guardian

China’s Lunar Test Spacecraft Takes Incredible Picture of Earth and Moon Together

Follow us on Google+ , Twitter and Facebook




The Chinese lunar test mission Chang’e 5T1 has sent back some amazing and unique views of the Moon’s far side, with the Earth joining in for a cameo in the image above. According to the crew at UnmannedSpaceflight.com the images were taken with the spacecraft’s solar array monitoring camera.



A closeup of Mare Marginis, a lunar sea that lies on the very edge of the lunar nearside. Credit: Xinhua News, via UnmannedSpacefight.com

The mission launched on October 23 and is taking an eight-day roundtrip flight around the Moon and is now journeying back to Earth. The mission is a test run for Chang’e-5, China’s fourth lunar probe that aims to gather samples from the Moon’s surface, currently set for 2017. Chang’e 5T1 will return to Earth on October 31.

The test flight orbit had a perigee of 209 kilometers and reached an apogee of about 380,000 kilometers, swinging halfway around the Moon, but did not enter lunar orbit.



A view of Earth on October 24, 2014, from the Chinese Chang’e-5 T1 spacecraft.

Source : universe today

NASA Releases Sounds From Space On SoundCloud

NASA recently released over a half a century of sounds on SoundCloud, ranging from eerie noises from our solar system to historic moments in space exploration. The U.S. space agency recently created a SoundCloud page to reveal some of the most unusual sounds ever recorded, according to Mother Nature Network.

Although sounds in space are stifled by a vacuum, scientists have discovered ways of capturing noise using special instruments on the Voyager space probe that converts electromagnetic vibrations into sound, Gigwise reports.

The recordings include sounds of Saturn’s rings, Neptune, Jupiter, and Uranus, as well as what Earth would sound like millions of miles away. The files also contain sounds of shuttle launching and famous quotes from NASA astronauts.

Some of the sounds are quirky, chilling, and otherworldly. Here are seven of NASA’s most interesting uploads.

1. “Earthsong” It is also called “Chorus” and is NASA’s most popular feed. The sound is produced by our own planet. It is described as an electromagnetic phenomenon caused by plasma waves in Earth’s radiation belts that hover 8,000 miles above the surface. The sound is too high for humans to hear, however ham radio operators have detected it for a long time, especially in the morning. It has been compared to the sound of birdsongs, from which the moniker is derived. NASA recorded this in 2012 with its EMFISIS probe.


2. “Saturn Radio” Saturn is home to dramatic auroras that are a lot like the northern and southern lights that dance around the Earth’s poles when solar wind hits the upper atmosphere. These lights are closely related to the planet’s strong radio emissions, first detected by the Cassini spacecraft 2002.


3. “Interstellar Plasma” It has taken NASA’s Voyager 1 three decades since it left Earth to escape the sun’s magnetic field. This clip represents data that was recorded outside the heliosphere in 2012 and 2013. NASA calls it “The Sounds of Interstellar Space.”


4. “Sonified Starlight” Scientists now may “sonify” non-auditory data by translating its values to noises, a lot like a Geiger counter converts silent radiation to audible clicks. Locating patterns in in data is often easier by ear, even if the data doesn’t represent sounds. The technique also helps scientists understand faraway stars, as with this clip of sonified light waves from KIC 7671081B, a variable star listed in NASA’s Kepler Input Catalog (KIC).


5. “Eerie Enceladus” This is Saturn’s sixth-largest of its several dozen moons. Enceladus spews enormous plumes of water vapor from its ice-covered surface. In 2005, the Cassini spacecraft detected a “significant atmosphere around it,” recording data from ion cyclotron waves.


6. “A Giant Leap” Neil Armstrong’s most famous words when his foot touched the surface of the moon. This was the first SoundCloud clip that NASA posted online.


7. “Lift Off” These are the sounds of the first manned-mission to the moon, Apollo 11. The clip includes lift off, as well as the applause in the space center.

Some of NASA’s files might sound familiar to gamers.

NASA’s release of sounds from space on its SoundCloud page comprises of 63 files so far, including several of the most historic and mind-bending moments from the past 50 years of space exploration.
Source : inquisitr

'Interstellar' Black Hole is Best Black Hole in Sci-Fi

Follow us on Google+



Christopher Nolan’s movie ‘Interstellar’ will be an epic space adventure encapsulating humanity’s need to explore the Universe, but it’s the visual effects for the movie that are garnering early attention.

By combining the help of one of the world’s leading black hole physicists with a cutting-edge visual effects (VFX) team, ‘Interstellar’ will depict the most scientifically accurate black hole in science fiction history. And, during production, some new discoveries were made as to how a black hole would appear if we could view it up close.

“Neither wormholes or black holes have been depicted in any Hollywood movie in the way they actually would appear,” said Caltech physicist Kip Thorne in a behind-the-scenes video released by Paramount Pictures (featured below). “This is the first time that the depiction (of a black hole) began with Einstein’s general relativity equations.”

General relativity describes the nature of gravity. How a black hole, being the most gravitationally dominant object in the known Cosmos, would look to an observer can therefore be described by Einstein’s equations — except for when tangling with the Black Hole Information Paradox, then you’ll need some quantum equations to boot.

Thorne is a lifelong friend of fellow black hole guru Stephen Hawking and between both of the theoretical physicists, our modern understanding of how these singularities work has flourished. So with the help of Thorne, Nolan has done something very smart; he’s been able to provide the movie-viewing public with a rare sci-fi look into the actual science of a black hole while maintaining an artistic representation that we can easily comprehend.

Interstellar Movie Trailer #3

http://www.youtube.com/watch?v=ePbKGoIGAXY

Warped Spacetime

While crunching the mathematics and arriving at graphical representations of Einstein’s famous equations, Thorne and the movie’s VFX team realized that if a star is positioned behind the black hole, the starlight may become trapped in the warped spacetime close to the black hole’s event horizon. Known as gravitational lensing, this spacetime effect can be used by astronomers to detect exoplanets, for example. But during the production of ‘Interstellar,’ the team realized a spacetime subtlety.

The Matter of an Accretion Disk

Of course, no black hole would be complete without the addition of a radiating accretion disk. But how would that appear on film?

As matter falls toward the spinning black hole’s event horizon, the gas collects into a hot accretion disk, shining brilliantly. By adding the disk, “we found that if you then render this whole thing and you visualize it all through this extraordinary gravitational lens, the gravity twists this glowing disk of gas into weird shapes and you get this extraordinary ‘rainbow of fire’ across the top of the black hole,” said Franklin.

Science fiction movies are produced to entertain, first and foremost. But as computer graphics become more sophisticated and the science fiction-viewing public becomes more savvy, there is a growing motivation by filmmakers to make space phenomena as ‘real’ as possible. And often that will mean employing the help of scientists to make our most extreme space fantasies as scientifically accurate as possible to maintain a credible storyline.

‘Interstellar’ is shaping up to be one of those rare movies that will combine science and fiction, exciting the viewing public, potentially engaging us with astrophysics in a way we’ve never experienced before.

Source : Discovery News

Scientists Create 3D Map of Cosmic Web for the First Time Showing 'Adolescent' Universe

Using extremely faint light from galaxies 10.8 billion light-years away, scientists created one of the most complete, 3D maps of the early universe. 3D map of the cosmic web at a distance of 10.8 billion years from Earth, generated from imprints of hydrogen gas observed in the spectrum of 24 background galaxies behind the volume. (Photo : Casey Stark (UC Berkeley) and Khee-Gan Lee (MPIA))

y have managed to create a map of what our universe looked like during its adolescence. Using extremely faint light from galaxies 10.8 billion light-years away, the researchers created one of the most complete, 3D maps at a time when the universe was made of a fraction of the dark matter we see today.

In this case, the researchers used a new technique for high-resolution universe maps. This technique, which uses distant galaxies to backlight hydrogen gas, could actually also inform future mapping projects, such as the proposed Dark Energy Spectroscopic Instrument (DESI).

Before this study, no one knew if galaxies further than 10 billion light-years away could provide enough light to be useful. Yet the Keck-1 telescope collected four hours of data during a brief break in cloudy skies and showed that it was possible to do so. Because of the extreme faintness of the light, though, the scientists had to develop algorithms to subtract light from the sky that would otherwise drown out the galactic signals.

"It's a pretty weird map because it's not really 3D," said David Schlegel, one of the researchers, in a news release. "It's all these skewers; we don't have a picture of what's between the quasars, just what's along the skewers."

The resulting map, though, shows that this technique is possible for future maps.

"This technique is pretty efficient and it wouldn't take a long time to obtain enough data to cover volumes hundreds of millions of light-years on a side," said Khee-Gan Lee, the lead researcher.

The findings reveal a bit more about the early universe and show that this technique could be huge when it comes to peering even further back into the past. That said, scientists will need to collect more data before this becomes a possibility.

Source : Science World Report

X-Class Solar Flare, 4th Major Eruption On The Sun This Week Detected

It’s been a busy week for earth’s star, with a partial solar eclipse delighting space watchers Thursday, and three earlier solar flares captured on NASA’s cameras.

The NOAA’s space weather tracking detected the X3.1 class flare Friday, beginning just after two in the afternoon, Pacific time, and lasting till after 3 p.m.

Flares of this strength can disrupt radios and navigational equipment, but harmful radiation is absorbed by the earth’s atmosphere.



One legendary solar flare in 1989 actually shut down power grids in the U.S. and Canada. That was an “X15″ class flare, exponentially more powerful than this week’s flares.

An X1.6 class flare erupted on Tuesday. X is the strongest class, and an X2 is twice as strong as an X1.

An M-class or mid-level solar flare peaked at 6:59 p.m. Tuesday night, as measured by NASA’s Solar Dynamics Observatory.

A third flare, an X1.1 on October 19th also sent radiation toward earth.

These solar eruptions can trigger larger than usual northern lights also known as the Aurora Borealis, sometimes making the glow visible as far south as Northern California.

NOAA Space Weather Scale descriptions can be found at
http://www.swpc.noaa.gov/NOAAscales

Source : CBS Local

IF YOU THINK THAT EARTH IS VERY LARGE THEN JUST TAKE A LOOK AT THIS VIDEO

http://www.youtube.com/watch?v=HEheh1BH34Q

 

Did Venus give Earth the moon?

 

 



 

 

LONDON —The Earth's moon may be a present from Venus, which once had a moon and then lost it, a new theory suggests. Under the theory, Earth's gravity captured Venus' old moon, giving our planet its big natural satellite.

This idea contrasts to the thinking of the vast majority of moon researchers, who believe that the Earth's moon formed some 4.5 billion years ago when a planet-size body slammed into nascent Earth at high speed.

This giant impact hypothesis, however, has its own issues, as did all the alternative moon formation theories discussed this week at the Origin of the Moon conference at the Royal Society here. [The Moon: 10 Surprising Lunar Facts]

"I think part of the key to [understanding] the moon may be that Venus has no moon, and we certainly have to study it (Venus) more," said Dave Stevenson, professor of planetary science at the California Institute of Technology, who proposed the Venus idea at the conference. In an interview with SPACE.com after his presentation, Stevenson said that he himself favored the impact theory on moon formation, but unfortunately this theory did not yet answer all the questions.

How did Earth get its moon?
The "moon capture" theory assumes that Earth used its gravitational pull to attract a pre-formed space body into its orbit, thus making a satellite of this object. [How the Moon Formed: A Lunar Tour (Video)]

However, the geochemical composition of the moon and Earth likely trips up this theory. Analyses of the lunar rocks brought back by NASA's Apollo moon landing missions have shown that the satellite has an isotopic composition very similar to that of Earth.

Isotopes refer to varieties of chemical elements that have the same number of protons, but different numbers of neutrons. Two isotopes behave the same chemically.

And if both moon and Earth have very similar isotopes, it makes the capture theory difficult to maintain, said Alex Halliday, head of science at Oxford University. Such isotopic similarities suggest that "the material that makes up the moon did actually either come out of the Earth, or that the stuff that was in the disk that formed the moon got completely mixed up with the stuff in the Earth."

Nonetheless, some aspects of the idea that the moon may have come from Venus are intriguing, he said.

"The reason why it's interesting is that Earth and Venus are close to each other. They have similar mass, and people think they have probably formed in a similar way," he said. "So the question is, if Earth and Venus formed in similar ways, how come the Earth has a moon and Venus doesn't?"

Stevenson's idea would answer that question, Halliday said, "throwing a new twist into the whole capture theory."

There are many theories for what might have caused such a large moon for a planet as small as Earth. The most popular theory assumes an impact, where the debris of the collision — a mix of the material from Earth and the other body — gave birth to the moon. This body then stayed in orbit about the Earth, forever bound to its new home.

Another posits that the moon "fissioned" from the Earth's crust and mantle due to the centrifugal force of a rapidly spinning early Earth.

Another theory, called binary accretion, assumes that the moon was born at the same time and place as Earth.



 

 

Wandering moons
The biggest flaw of the fission, capture and binary accretion theories is that they cannot account for the high angular momentum of the Earth-moon system.

Scientists believe that initially the Earth was spinning so rapidly that a day lasted only five or six hours, and the moon was in a very low-altitude orbit. But gradually, tidal drag slowed the Earth's spin and pushed the moon's orbit up to its present level.

The capture theory will always face a challenge explaining the similar composition of the moon and Earth, Stevenson said. But if scientists analyze rocks from Venus and they turn out to be very similar to those on Earth, that would argue in favor of the capture theory. The giant impact idea also has trouble explaining why the Earth and the moon are so peculiarly similar.

Even though he himself favors the impact theory, Stevenson said he picked Venus for a larger purpose.

"We cannot understand the terrestrial planets unless we understand Venus, and at the moment, we don't know anything about Venus in terms of the isotopes" it has, he says. "And I also think that as a test of our understanding of the origin of the moon, we need to understand whether Venus ever had a moon."

If Venus indeed once had a moon and lost it, how might the planet have acquired a satellite in the first place?

Unlike what would have happened with Earth, the formation of any moon of Venus may have occurred much earlier, shortly after the formation of the solar system, Stevenson said.

Back then, there were still a lot of things whizzing around," he said.

So Venus possibly would have gotten its moon after an even earlier giant impact of some sort, and the planet may have lost its moon either by collision or by escape. This would mean an object passed close by the Venus system and caused the moon to depart from its orbit, says Stevenson.

But even aside from the Venus idea, the widely preferred giant impact theory still "is not satisfactory in all respects," Stevenson said.

Sean Solomon, the director of the Lamont-Doherty Earth Observatory of Columbia University, agrees. "We are still on the trail of the detailed scenario that would seem both likely and complete in its ability to account for all the geochemical and geophysical observations," he said.

Until scientists have figured out that scenario, even the escaped moon of Venus is a plausible theory, he said.

"Even with the giant impact idea, we don't know the origin of the impacting object. It could've been an early protoplanet. It could've been a moon of another object that was removed from the gravitational field of its original [planet]. It could've been a very large asteroid. All of those scenarios are still open."