By Jonathan Amos Science correspondent, BBC News

The US space agency Nasa has launched its Solar Dynamics Observatory (SDO) from Cape Canaveral in Florida.

It was the second lift-off attempt for the mission after Wednesday's effort was postponed due to high winds.

The observatory is designed to acquire detailed images of our star to explain variation in its activity.

An active Sun can disrupt satellite, communication and power systems on Earth - especially when it billows charged particles in our direction.

Scientists want to see if they can forecast this "space weather" better.

The Atlas V carrying SDO left Earth at 1023 local time (1523 GMT). Its flight to separation of the spacecraft in orbit lasted almost two hours.

Once ejected from the rocket's Centaur upper-stage, SDO immediately deployed its solar panels to charge its batteries and start operating its systems.

"They're power-positive so all those things they wanted to do in those first few minutes have gone like clockwork," said Nasa launch director Omar Baez.

High-definition, high-speed

The Solar Dynamics Observatory will investigate the physics at work inside, on the surface and in the atmosphere of the Sun.

"SDO is the solar variability mission," said Lika Guhathakurta, the SDO programme scientist at Nasa Headquarters.

"It is going to revolutionise our view of the Sun and it will reveal how solar activity affects our planet, and help us anticipate what lies ahead.

"It will observe the Sun faster, deeper and in greater detail than any previous observations, breaking barriers of time, scale and clarity that have long blocked progress in solar physics."