Mercury's 'dynamic and complex world' revealed by Nasa's Messenger

First time planet has high-resolution maps after Nasa spacecraft orbited planet over course of a year

Mercury is the smallest of the solar system's eight planets and, for decades, also its most neglected by humans. While Mars, Venus, Jupiter and Saturn have been probed and photographed in exquisite detail during the space age, the closest planet to the Sun has had to make do with a few flybys from the Mariner 10 spacecraft in the early 1970s.

Now Mercury has its own high-resolution maps, down to the scale of kilometres, made from thousands of images taken by Nasa's Messenger spacecraft as it orbited the planet over the course of a year.

"Messenger has revealed Mercury to be a fascinating, dynamic and complex world," said David Blewett at the Applied Physics Laboratory at Johns Hopkins University and a scientist for the Messenger mission. Part of the reason, he said, that it had taken more than 30 years to revisit the planet since the Mariner 10 flybys was that most people thought Mercury was probably like the moon and largely inert and boring.

"We know now that it is an oddball planet," said Blewett, speaking ahead of a briefing on Friday at the annual meeting of the American Association for the Advancement of Science in Boston. "It's the smallest of the eight planets but has the highest density. The interior structure is different than the other planets. The geologic surface is different to the moon and Mars. The surface composition is enigmatic because ... it consists of rock types that we don't have much experience with. It has a global, Earth-like magnetic field, Venus and Mars do not."

The new global colour map is an enhanced image that shows the different compositions of rocks on the surface of Mercury. The more orange areas are volcanic plains while the make-up of the rocks in the deep blue areas is unknown. Though Messenger was able to detect the abundance of individual elements on Mercury's surface - including iron, titanium, sulphur and potassium - without rock samples to study, scientists cannot determine the exact compounds or minerals in which those elements are arranged.

Mercury orbits the sun in an eccentric orbit that gets as close as 46m kilometres and never goes further than 70m kilometres from our star (earth, for comparison, stays about 150m kilometres away). This means the surface of the planet can reach more than 400C.

Nasa's Messenger spacecraft made its first flyby of the planet in 2008 and began to orbit in early 2011, since when it has been mapping and measuring the surface of the planet. In November 2012, Nasa announced there was water ice and tar-like organic molecules at Mercury's poles. Because the planet's axis of rotation around the sun barely tilts from the vertical, the deepest parts of craters at the polar regions never get sunlight and the temperatures there are about -200C. The presence of ice and organic compounds lends weight to the idea that the planet was pummeled by icy comets during the early years of the solar system.

The biggest surprise for researchers is that, on the surface, the abundance of relatively volatile elements such as potassium and sulphur is so high. Most of the models for the formation of Mercury predict that these elements should have evaporated away during the planet's formation.

"The big problem in making Mercury is how do you get a planet that has such a huge iron core and such a small proportion of rock? One of the ideas was that maybe there was a giant impact that stripped off much of the rocky outer layers and left you with unusually high proportion of iron in the core," said Blewett. But Messenger's data, he said, meant planetary scientists would have to come up with new ideas.

One alternative candidate is that the chemical conditions in the inner part of the nebula where Mercury was forming were different than scientists had expected, and this probably allowed iron to condense first, while the rockier parts of the planet were swept away. "That model seems to predict the correct sulphur and potassium abundance for the surface and that's probably the leading contender right now," said Blewett.

The Science of Love: It's Kind of Like Cocaine

Valentine's Day. Blerg. But hey, if we're going to be surrounded by corporate sponsored true love, we may as well have some fun. Here's a video from ASAPScience describing the way love works, scientifically. It's a little more complicated than you might have realized.

First, well, yes. It's like cocaine. Basically, it makes it easier for us to experience pleasure. But it's also key in protecting our young and relatives. That makes sense, since we're created by an unbroken line of organisms going back to the very first life form. So we must have evolved to love our young pretty hard! So there, love is a helicopter parent. Enjoy Valentine's Day. [YouTube]

Asteroid to pass closer to Earth than TV satellites

Rock measuring 46 metres across is expected to come within 17,100 miles but will not hit Earth, says Nasa

A small asteroid will pass closer to Earth next week than the TV satellites that ring the planet, but there is no chance of an impact, Nasa has said.

The celestial visitor, known as 2012 DA14, was discovered last year by a group of amateur astronomers in Spain. The asteroid is about the size of an Olympic swimming pool at 46 metres (150ft) in diameter and is projected to come as close as 17,100 miles (27,520km) from Earth during its approach on 15 February.

That would make it the closest encounter since scientists began routinely monitoring asteroids about 15 years ago.

Television, weather and communications satellites fly about 500 miles (800km) higher. The moon is 14 times farther away.

Even so, "no Earth impact is possible", the astronomer Donald Yeomans, with Nasa's Jet Propulsion Laboratory in Pasadena, California, told reporters during a conference call.

The time of the asteroid's closest approach will be 7.24pm GMT (2.24pm EST) - daylight in the US but dark in Europe, Asia and Australia, where professional and amateur astronomers will be standing by with telescopes and binoculars to catch a glimpse.

DA14 will soar through the sky at about 8 miles (13km) a second. At that speed, an object of similar size on a collision course with Earth would strike with the force of about 2.4m tonnes of dynamite. The last time that happened was in 1908 when an asteroid or comet exploded over Siberia, levelling 80m trees over 830 square miles (2,150 sq km).

"Although they wouldn't [cause] a global catastrophe if they impact the Earth, they still do a lot of regional destruction," said Lindley Johnson, who oversees the Near-Earth Object Observations Programme at Nasa's headquarters in Washington DC.

Nasa has been on a mission to find and track all near-Earth objects that are 0.62 miles (1km) in diameter or larger. The effort is intended to give scientists and engineers as much time as possible to learn if an asteroid or comet is on a collision course with Earth, in the hope of sending up a spacecraft or taking other measures to avert catastrophe.

About 66m years ago, a six-mile (10km) diameter object smashed into what is now the Yucatan peninsula in Mexico, leading to the demise of the dinosaurs as well as most plant and animal life on Earth.

The planet is regularly pelted with objects from space, adding up to about 100 tonnes of material a day, Yeomans said.

"Basketball-sized objects come in daily. Volkswagen-sized objects come in every couple of weeks. As you get to larger and larger sizes the number of objects out there is less and less, so the frequency of hits goes down," Yeomans said.

Something the size of DA14 can be expected to strike Earth about every 1,200 years.

"For objects of this size, this is the closest predicted encounter that we're aware of," Yeomans said.

Just How Does Time Travel Work

It seems that the idea of actually being able to travel in time is being dismissed more than these days, which is a bit annoying considering that as a child I was told that in the 21st century we would have flying cars, free electricity and we would live forever!

How Time Travel Works from Flavorwire on Vimeo.

However, it does look like there are folk backers for the time travel problem and so this handy video should explain to us exactly how time travel works. They are using scenes from popular movies and some scientific facts, what could possibly go wrong here.

Source [Geeks Are Sexy]