Asteroid Crash May Have Caused Mercury’s Strange Spin

A collision with an asteroid might have set the planet Mercury whirling oddly in its orbit, a new study suggests.

Scientists had long assumed that Mercury was tidally locked with the sun — the planet’s tiny size and proximity to the sun suggested the star’s gravitational pull would quickly force Mercury into such a state. However, radar observations of Mercury surprisingly revealed that the planet led a far stranger life, rotating three times on its axis for every two orbits it completes around the sun. Now, researchers suggest that Mercury was once tidally locked, initially spinning in the opposite direction to its orbit.

“Mercury once had a spin rate synchronous with the sun, like the moon with the Earth,” study co-author Alexandre Correia, a planetary scientist at the University of Aveiro in Portugal, told SPACE.com.

Computer models suggest that a giant impact from an asteroid then knocked it into its current strange configuration. Evidence of this collision might include Caloris Basin, Mercury’s largest impact crater, which matches the predicted size, age and location of the impact, the researchers said. “It is the perfect candidate,” Correia said.

Such an impact might also explain certain hollows seen on Mercury’s surface. If the planet was tidally locked, one side would have been extremely bright and hot while the other extremely dark and cold. Substantial deposits of ice might have accumulated on the dark half, some of which might have been buried under matter ejected from impacts. When Mercury’s spin later changed and daylight began falling on the once dark side, this buried ice might have vaporized, leaving behind hollows, the researchers explained.

The results of the study were published online today (Dec. 11) in the journal Nature Geoscience.

 

Source: Space.com

‘UFO’ Near Mercury Photographed

Is a giant, cloaked spaceship orbiting around Mercury? That’s been the speculation from some corners after a camera onboard NASA’s STEREO spacecraft caught a wave of electronically charged material shooting out from the sun and hitting Mercury.

Theorists have seized on the images captured from the “coronal mass ejection” (CME) last week as suggestive of alien life hanging out in our own cosmic backyard. Specifically, the solar flare washing over Mercury appears to hit another object of comparable size. “It’s cylindrical on either side and has a shape in the middle. It definitely looks like a ship to me, and very obviously, it’s cloaked,” YouTube-user siniXster said in his video commentary on the footage, which has generated hundreds of thousands of views this week. Now, how this user was able to determine that the object was “obviously” a cloaked spaceship with no other natural explanation remains as much a mystery as the object itself.

Of course, there’s another scientifically sanctioned explanation for the curious images, though we’re not certain that skeptics and UFO enthusiasts such as SiniXster will endorse it. Natalie Wolchover of Life’s Little Mysteries put the question to scientists in the solar physics branch at the United States Naval Research Laboratory (NRL). They’re the people who analyze data from the Heliospheric Imager-1 (HI-1)–better known in this context as the camera that shot the footage in question.

Head NRL group scientist Russ Howard and lead ground systems engineer Nathan Rich say the mysterious object is in fact Mercury itself. And what we’re seeing in the footage is the equivalent of Mercury’s wake, “where the planet was on the previous day,” as it travels through the solar system on its natural gravitational path.

 

Source: Yahoo! News

Image: Sott.net