They occurred near the planet's surface, astronomers say

Mar 6, 2012 16:08 GMT  ·  By

Recent observations of Venus have revealed that several hot flow anomalies (HFA) occurred right above the surface of the planet recently. These events resemble enormous explosions, and this particular planet is usually very affected by them.

Similar events have been detected in the past around other planets in the solar system, including Earth, Mars and Saturn. However, all of these worlds have strong magnetospheres – with the exception of the Red Planet – that prevent the HFA from occurring anywhere but high in the atmosphere.

In the case of Venus, the absence of a magnetosphere allows for these detonations caused by solar energy to occur very close to the planet's surface, even though an atmosphere surrounds the world.

On Earth, the magnetosphere is created by the motions of the planetary core, and also by the dynamo effect caused by the motions of material inside the planet. Significant heat differences exist between the mantle, crust and outer core, and the flow of magma between these zones contributes as well.

What a magnetosphere does is basically protect the planet underneath from the harmful effects of cosmic radiations and massive solar flares. In addition, it also contributes to keeping a rather intact atmosphere around the planet.

Without it, atmospheres are usually eroded away sooner or later. Venus is dead inside, which means that its protective magnetic field has long since dissipated. This is the main reasons why the massive explosions occurred so close to its surface, Space reports.

Scientists also found that the patterns in which the hot flow anomalies occurred were different at Venus from those observed high above Earth. The new study was led by Glyn Collinson, who holds an appointment with the NASA Goddard Space Flight Center, in Greenbelt, Maryland.

“Hot flow anomalies release so much energy that the solar wind is deflected, and can even move back toward the Sun. That's a lot of energy when you consider that the solar wind is supersonic and the HFA is strong enough to make it turn around,” GSFC expert and study coauthor David Sibeck adds.

When occurring close to Earth, HFA can easily compress the entire magnetosphere protecting our planet, and then allow for highly-charged particles released by the Sun to travel alongside magnetic field lines at both poles.

“At Earth, HFA have a big effect, but don't necessarily rule the roost. But at Venus, since the HFA happens right up next to the planet, it is going to have a more dramatic effect on the system,” Collinson concludes.

Details of the new study appear in a paper published in the February 29 online issue of the esteemed Journal of Geophysical Research.