Smallest planet shrinks in size

The smallest planet in the Solar System has become even smaller, studies by the Messenger spacecraft have shown.

Data from a flyby of Mercury in January 2008 show the planet has contracted by more than one mile (1.5km) in diameter over its history.

Scientists believe the shrinkage is due to the planet's core slowly cooling.

Studies published in the journal Science show the same process also powers the planet's magnetic field, a topic long debated by scientists.

"Cooling of the planet's core not only fuelled the magnetic dynamo, it also led to contraction of the entire planet," said Principal Investigator Sean Solomon of the Carnegie Institution of Washington, US.

"And the data from the flyby indicate that the total contraction is at least one-third greater than we previously thought."

Active youth

The Messenger (Mercury Surface, Space Environment, Geochemistry and Ranging) spacecraft passed within 200km (125 miles) of Mercury earlier this year.

It was the first time the planet had been viewed up close since Mariner 10's third and final fly-by in March 1975.
A kidney-shaped volcanic vent surrounded by ejected material

The flyby was one of three to be made by the craft as it prepares to enter into orbit around the Solar System's smallest planet in 2011.

Just days after the pass, scientists revealed that they had found evidence of volcanic activity on the planet, previously hinted at by Mariner 10.

Further analysis of areas such as the Caloris basin, one of the Solar System's largest and youngest impact basins, found volcanic vents and evidence of "pyroclastic" debris blown from the volcano as it erupted.

Other areas contained circular structures with wrinkled edges, similar to structures seen on the Moon and Mars.

Scientists believe these are impact craters that have been filled with massive quantities of lava, possibly 2.7km (1.3miles) deep.

"That's a lot of lava," said Dr James Head of Brown University. "It shows the planet was really active in its early history."

Researchers believe the peak of activity could have been three to four billion years ago.

Core effects

Sensors, such as the Fast Imaging Plasma Spectrometer (FIPS), onboard the craft also revealed details of the planet's atmospheric composition.

FIPS recorded silicon, sodium and even water ions around Mercury. Ions are electrically charged atomic particles.

The scientists believe these were blasted from the surface of the planet by the solar wind, a stream of charged particles which buffets the Solar System.

Mercury's proximity to the Sun means it feels the full force of this wind, blasting atoms into space. Many of these are then trapped by the planet's magnetic field.

"The Mercury magnetosphere is full of many ionic species, both atomic and molecular," said Dr Thomas Zurbuchen of the University of Michigan.

This magnetosphere is created by the planet's core, which accounts for 60% of the planet's mass.

As well as influencing the space around the planet, the core has had an immense influence on surface features.

"The dominant tectonic landforms on Mercury, including areas imaged for the first time by Messenger, are features called lobate scarps, huge cliffs that mark the tops of crustal faults that formed during the contraction of the surrounding area," explained Dr Solomon.

"They tell us how important the cooling core has been to the evolution of the surface."

Google Changes Home Page, Adding Link to Privacy Policy

Google tries tighter aim for Web ads.
Google, with its deep reservoir of data about online behavior gathered by tracking hundreds of millions of computers, is for the first time testing ways to use some of that data to aim ads at Web users
Google Homepage Adds Privacy Lin
Google's homepage at google.com has been changed: the search engine leader has decided that a privacy link, which leads to the company's straightforward Privacy Center, should be fit somewhere on its first page. But there was also the company policy of keeping things neat and thin, with a fixed word count of 28 words on the homepage.

What could then be removed to make room for the "Privacy" word and link? Looking around, there was this one word that seemed superfluous: Google, in the copyright notice at the bottom of the search homepage. Consequently, the "©2008 Google" was changed into "©2008 Privacy," with the Privacy hyperlinked to www.google.com/intl/en/privacy.html

Marissa Mayer, VP Search Products & User Experience at Google, explained the whole word count thing on a company blog. Apparently they got into the whole "keep it thin" thing after a user kept sending cryptic emails which had a number as subject. The messages were like "61, getting a bit heavy, aren't we?" Finally, the mystery was cracked and Mayer realized that the person was talking about the number of words on the Google homepage, which were only 13 when it was launched back in 1999.

What Marissa Mayer doesn't mention is that privacy organizations wrote to Google CEO Eric Schmidt last month requesting such as change. It appears that California law requires that all pages have a privacy link on their homepage.

The petition was signed by representatives from Privacy Rights Clearinghouse, the World Privacy Forum, Consumer Action, the Electronic Frontier Foundation, The American Civil Liberties Union of Northern California and the Consumer Federation of California.

At first, Google said its privacy policy was easily accessible to users, and available to anyone through the “About Google” link. Furthermore, Google says that by adding it, it would change the purposely plain home page. According to California’s Online Privacy Protection Act of 2003, all companies need to put their privacy policy on their home page. However, Google did not completely ignore the law, which also states that the privacy policy can also be placed where a reasonable person would notice it.

The company said last month that anyone could simply type the words “Google privacy policy” and the search engine will find the page for them. However, it seems that Google wanted to play it safe and comply with the request in a more straightforward way.

more.........

The word “privacy” now appears on Google’s home page, with a link to the company’s privacy policy.
With that one word, the Web search giant heads off the growing controversy over whether its previous practice ran afoul of a California law, the California Online Privacy Protection Act of 2003, which requires the operator of a commercial Web site that collects personal information to link to its privacy policy from its home page.
When I wrote in May that Google appears to be violating the law, Google told me that it did not believe that it was required to put a link on its home page. The company said that its privacy policy was easy enough to find, either on the page called “About Google” or by searching for “Google privacy policy” on its search engine.
Later, I spoke to Joanne McNabb, the chief of California’s Office of Privacy Protection, who said that her agency believes that Google should have a link to its privacy policy on its home page. After the issue buzzed about the blogosphere, four privacy groups wrote Google urging it to change its practices.
Google announced its change of heart on both

Some users, bloggers, and regulatory bodies have asked us why we didn’t have a link, and, after evaluating, we decided that it was the right time to add one. While users have always been able to easily search for and find our policy before, or click through to it, this provides an easier path to learning about our privacy approach. We’ve also added the same link on the results page, as many users arrive on them directly.