Profile image
Story Views

Now:
Last Hour:
Last 24 Hours:
Total:

Leaky atmosphere linked to lightweight planet

Friday, February 9, 2018 10:07
% of readers think this story is Fact. Add your two cents.

Solar wind at Mars [image credit: universetoday.com]

The researchers say ‘the solar wind likely only had a very small direct effect on the amount of Mars atmosphere that has been lost over time.’ This makes them suspect that ‘a magnetic field is not as important in shielding a planet’s atmosphere as the planet’s gravity itself.’ It was always hard to see how the magnetic shield theory worked when Venus with its dense atmosphere has little magnetism.

The Red Planet’s low gravity and lack of magnetic field makes its outermost atmosphere an easy target to be swept away by the solar wind, but new evidence from ESA’s Mars Express spacecraft shows that the Sun’s radiation may play a surprising role in its escape, reports Phys.org.

Why the atmospheres of the rocky planets in the inner solar system evolved so differently over 4.6 billion years is key to understanding what makes a planet habitable.

While Earth is a life-rich water-world, our smaller neighbour Mars lost much of its atmosphere early in its history, transforming from a warm and wet environment to the cold and arid plains that we observe today. By contrast, Earth’s other neighbour Venus, which although inhospitable today is comparable in size to our own planet, and has a dense atmosphere.

One way that is often thought to help protect a planet’s atmosphere is through an internally generated magnetic field, such as at Earth. The magnetic field deflects charged particles of the solar wind as they stream away from the Sun, carving out a protective ‘bubble’ – the magnetosphere – around the planet.

At Mars and Venus, which don’t generate an internal magnetic field, the main obstacle to the solar wind is the upper atmosphere, or ionosphere. Just as on Earth, solar ultraviolet radiation separates electrons from the atoms and molecules in this region, creating a region of electrically charged – ionised – gas: the ionosphere. At Mars and Venus this ionised layer interacts directly with the solar wind and its magnetic field to create an induced magnetosphere, which acts to slow and divert the solar wind around the planet.

For 14 years, ESA’s Mars Express has been looking at charged ions, such as oxygen and carbon dioxide, flowing out to space in order to better understand the rate at which the atmosphere is escaping the planet.

The study has uncovered a surprising effect, with the Sun’s ultraviolet radiation playing a more important role than previously thought.

“We used to think that the ion escape occurs due to an effective transfer of the solar wind energy through the martian induced magnetic barrier to the ionosphere,” says Robin Ramstad of the Swedish Institute of Space Physics, and lead author of the Mars Express study.

“Perhaps counter-intuitively, what we actually see is that the increased ion production triggered by ultraviolet solar radiation shields the planet’s atmosphere from the energy carried by the solar wind, but very little energy is actually required for the ions to escape by themselves, due to the low gravity binding the atmosphere to Mars.”

Continued here.



Source: https://tallbloke.wordpress.com/2018/02/09/leaky-atmosphere-linked-to-lightweight-planet/

We encourage you to Share our Reports, Analyses, Breaking News and Videos. Simply Click your Favorite Social Media Button and Share.

Report abuse

Comments

Your Comments
Question   Razz  Sad   Evil  Exclaim  Smile  Redface  Biggrin  Surprised  Eek   Confused   Cool  LOL   Mad   Twisted  Rolleyes   Wink  Idea  Arrow  Neutral  Cry   Mr. Green

Loading...
Top Stories
Recent Stories
 

Featured

 

Top Global

 

Top Alternative

 

Register

Newsletter

Email this story
Email this story

If you really want to ban this commenter, please write down the reason:

If you really want to disable all recommended stories, click on OK button. After that, you will be redirect to your options page.