Nasa's Curiosity Mars Rover Captures Rare Sunspots

While investigating bedrock types on Mars' Mount Sharp and preparing for a drill test, Curiosity tracked large sunspots from the opposite side of the Sun.

"Tracking the sunspot activity on the far side of the sun is useful for space-weather forecasting," said Yihua Zheng, project leader for Nasa space weather services.

"It helps us monitor how the sunspots evolve and grow before they become visible from this side," he added.

Scientists temporarily have no other resource providing views of the Sun from the opposite side of the solar system from Earth.

The sun completes a rotation about once a month faster near its equator than near its poles.

"Information about sunspots that develop before they rotate into view of Earth and Earth-orbiting spacecraft is helpful in predicting space-weather effects of solar emissions related to sunspots," the US space agency said in a statement.

Nasa's STEREO-A spacecraft, which monitors the Sun, is currently almost exactly behind the Sun from Earth's perspective and is temporarily out of communication.

The Sun disrupts radio transmissions that pass too close to it.

Communication with Curiosity was also suspended last month when Mars passed nearly behind the Sun but the rover resumed full communication and operations in late June.

Daily information from STEREO-A is expected to begin again this month.

Curiosity has been working on Mars since early August 2012.

It reached the base of Mount Sharp last year after fruitfully investigating outcrops closer to its landing site and then trekking to the mountain.

The main mission objective now is to examine successively higher layers of Mount Sharp.