Solar eruptions can affect planets without magnetic bubble

The Earth's life-sustaining atmosphere would probably have been severely affected by the Sun's flares if the Blue Marble did not have magnetosphere, a NASA study has revealed.

Magnetosphere is a natural magnetic bubble which protects a planet's atmosphere. Without it, a planet's atmosphere is intensely vulnerable to eruptions from the Sun, the study said.

On the Earth, the magnetosphere deflects some of the impact of the solar eruptions. Without it, the Earth would have become like its neighbour, Venus.

Larger eruptions of solar material called coronal mass ejections (CMEs) occur at times that can disrupt the atmosphere around a planet.

"What if the Earth did not have that protective magnetosphere? Is a magnetosphere a pre-requisite for a planet to support life?" asked Glyn Collinson, first author on the paper from NASA's Goddard Space Flight Centre in Greenbelt, Maryland.

The jury is still out on that, but "we examine such questions by looking at planets without magnetospheres like Venus," he said.

Collinson's work began with data from the European Space Agency's (ESA) Venus Express which arrived at Venus in 2006 and carried out an eight-year mission.

On December 19, 2006, the Sun ejected a small, slow-moving puff of solar material.

Four days later, this sluggish CME was powerful enough to rip away dramatic amounts of oxygen out of Venus' atmosphere and send it out into space where it was lost forever.

Venus is a particularly inhospitable planet: It is 10 times hotter than the Earth with an atmosphere so thick that the longest any spacecraft has survived on its surface before being crushed is a little over two hours.

Perhaps such vulnerabilities to the Sun's storms contributed to this environment.

"Regardless, understanding exactly what effect the lack of a magnetosphere has on a planet like Venus can help us understand more about the habitability of other planets we spot outside our solar system," the authors noted.

Near the Earth, we have several spacecrafts that can observe a CME leaving the sun and its effects closer to the Earth, but it is difficult to track such things near other planets.

"The more we learn about other worlds, the more we learn about the very history of our own home planet, and what made it so habitable for life to begin with," Collinson added.

Learning just why a small CME had such a strong impact may have profound consequences for understanding what makes a planet hospitable for life, concluded the study that appeared in the Journal of Geophysical Research.