Canadian astronaut Chris Hadfield says he could not resist sharing his life in space on social media, in his first public appearance since landing.

Canadian astronaut Chris Hadfield has been talking about his experiences on the International Space Station in his first public appearance since returning to Earth.

The financial recovery of BP from the disaster of the Deepwater Horizon oil spill is being put in jeopardy by the amounts of compensation being paid out to businesses in the Gulf of Mexico region.

A tornado has ripped through a town in the US state of Texas, resulting in six deaths, officials say.

A tornado rips through the town of Granbury in the US state of Texas, causing six deaths and destroying or damaging dozens of homes.

A threatened strike by liquor shop workers in the Canadian province of Ontario has drinkers scrambling to find other sources of alcohol.

A $15m computer that uses "quantum physics" effects to boost its speed is to be installed at a Nasa facility.

Provides an overview of the United States, including key events and facts about this superpower

A contemporary art sale at Christie's in New York makes $495 million (£325m), the highest total in auction history.

BP appeals to UK Prime Minister David Cameron to intervene over the escalating compensation costs of the Gulf of Mexico oil disaster.

The White House has promised new safeguards after it emerged that Internal Revenue Service (IRS) staff singled out conservative groups for extra scrutiny.

Prince Harry ends his visit to the US by playing in a polo match for his charity that helps people affected by HIV and Aids in Lesotho.

The planet-hunting space telescope, Kepler, has been hobbled by a broken reaction wheel, say scientists at Nasa.

The White House releases 99 pages of emails related to the attack on a US mission in Benghazi, Libya, on 11 September last year.

Former American football star OJ Simpson makes his case for a new trial on armed robbery charges, saying he did not get proper legal representation.

President Barack Obama announces the head of the US tax agency has quit, after it emerged his staff singled out conservative groups for extra scrutiny.

The strange beauty of infections under the microscope

A California woman convicted of killing her former boyfriend can be executed because of the cruel and heinous nature of her crime, a jury rules.

US Attorney General Eric Holder faces hostile questioning at a fractious congressional hearing on two scandals rattling the Obama administration.

Former football star and actor OJ Simpson is testifying at a Nevada court hearing on his request for a new trial in an armed robbery case.