Category: Earth

The traditional view of the Earth’s interior has the crust (where we live), the upper and inner mantle, the outer core, and the inner core; wrapped around each other like layers of an onion. But now textbooks will need to be revised. It turns out there’s an inner, inner core.

The core of Earth is known to have an inner core of solid iron about 2,400 km (1,500 miles). Wrapped around that is a fluid outer core that reaches 7,000 km across (4,300 miles). As the solid core rotates inside the fluid core, it generates the magnetic field that helps us navigate, and protects the planet from harmful radiation and the effects of the solar wind.

Geologists from the University of Illinois at Urbana-Chamaign have been probing the interior of the planet, trying to get a better sense of its structure. And that’s harder than it sounds. You can’t just look down through thousands of km of solid rock.

There were using the natural waves that pass through the Earth after earthquakes shake on the surface. The waves are bent and reflected as they pass through the various layers inside the planet.

The team was specifically studying how the waves were affected as they passed through the solid inner core and were surprised to see that it wasn’t a uniform sphere of iron.

Instead, the seismic waves clearly showed that there’s an additional layer at a diameter of 1,180 km (733 miles), which makes this less than half the diameter of the inner core.

This is the Earth’s inner, inner core.

So what is it? Here’s what the lead scientists, Xiaodong Song had to say:

“Our results suggest the outer inner core is composed of iron crystals of a single phase with different degrees of preferred alignment along Earth’s spin axis,” Sun said. “The inner inner core may be composed of a different phase of crystalline iron or have a different pattern of alignment.”

It’s still iron, just not in the same crystalline structure. Perhaps its time to give the layers new names, inner inner core doesn’t quite work for me.

Original Source: University of Illinois News Release

This picture was released a couple of days ago, but since it’s so special, it deserves a post on Universe Today. And besides, everyone secretly likes to look at pictures of themselves. And this is a picture of us: it’s the Earth and the moon, as seen from Mars. From the Mars Reconnaissance Orbiter, to be exact, and it was taken by the HiRISE Instrument on board, the High Resolution Imaging Science Experiment. That’s the same camera that gave us the images of the avalanche on Mars, so the capabilities of this instrument are quite spectacular. This image was snapped back in October 2007, from a distance of 142 million kilometers, and if you look closely, you can make out a few features on Earth.

The west coast outline of South America is at lower right on Earth, although the clouds are the dominant features. In fact, the clouds were so bright, compared with the Moon, that they almost completely saturated the filters on the HiRISE camera. The people working on HiRISE say this image required a fair amount of processing to make a such a nice-looking picture. Yes, I agree, we are looking quite nice.

The phase angle is 98 degrees, which means that less than half of the disks of the Earth and Moon have direct illumination from the sun; that’s the reason we only see about half of each object. The scientists working on HiRISE say they would be able to image the Earth and moon when they are fully illuminated, but only when they are on the opposite side of the sun from Mars. However, then the distance would be much greater and the image would show less detail.

At this distance, this HiRISE image has a scale of 142 km/pixel, giving the Earth diameter about 90 pixels and the Moon diameter 24 pixels.

And now, back to the target that HiRISE was originally designed for: Mars. Here’s a very colorful (and false color) image that highlights the different minerals in Nili Fossae on Mars, one of the potential landing sites for the Mars Science Laboratory rover. From the CRISM instrument, the on-board spectrometer, scientists can discern that this area on Mars contains iron and magnesium, minerals that also contain water.

Original News Source: HiRISE Web page

Global warming and subsequent climate change is directly linked with human activity on our planet. The greenhouse effect is amplified by our need for energy, burning fossil fuels and pumping vast quantities of CO₂ into our atmosphere. To make things worse, the plants that form the Earth’s “lungs” in the tropics are being destroyed on a massive scale, so less carbon dioxide can be scrubbed from the air. However, it’s not all bad news. Industry and agriculture also generate large amounts of excess nitrogen pollution and scientists now believe that this nitrogen (a main ingredient for fertilizer) may help to increase tropical plant growth by up to 20%…

From our high school classes, we all know that green plants, through photosynthesis, absorb atmospheric carbon dioxide. It is essential for plants to flourish. By far the largest absorbers of carbon dioxide are the tropical rainforests in the Amazon basin, central Africa and southern Asia. They are often referred to as the “lungs” of Earth, as they absorb much of the atmospheric CO₂ and provide balance to the carbon budget of our climate. If this resource is removed through wholesale deforestation, more CO₂ collects in the atmosphere and global warming is amplified by the increase of this greenhouse gas.

However, help may be at hand. Taking the results from over 100 previously published studies, David LeBauer and Kathleen Treseder from the University of California Irvine, believe they have found a trend that suggests a strong link between nitrogen pollution and increased plant growth in tropical regions. Increased plant growth is a welcomed consequence of human activity, as faster plant growth means more plants to absorb more CO₂. Although deforestation is a global catastrophe (much of the ancient forests will never recover and a vast proportion of plant and animal species are now extinct), the new research published in Ecology may influence future climate change models.

“We hope our results will improve global change forecasts.” – David LeBauer, UCI graduate student researcher of Earth system science and lead author of the study.

Nitrogen pollution comes in many forms, the most obvious being from agricultural activity (fertilizer) polluting water supplies and industrial burning emitting nitrogen into the air. What’s more, nitrogen pollution is on the increase, especially in developing countries.

Nitrogen pollution has often been ignored as a possible growth agent in the tropics, as other fertilizing elements are in short supply (typically, if one element is low, no matter how high the other element is, it will have little or no effect on plant growth). Phosphorus for example, is low in tropical regions, but according to the new research, this doesn’t seem to factor and plant growth is increased by 20% regardless.

LeBauer adds: “What is clear is that we need to consider how nitrogen pollution interacts with carbon dioxide pollution. Our study is a step toward understanding the far-reaching effects of nitrogen pollution and how it may change our climate…” It may only be a step, but at least it’s a positive one.

Source: Physorg.com

Nine key geographical factors have been highlighted as Earth’s critical climate controllers most at risk of slipping past their “tipping points”. This means that once damage reaches a certain point, there can be no recovery; the damage will continue in a downward spiral, amplifying global warming and environmental damage on historic scales. And as if climate news couldn’t get any worse, one such tipping point is only a year away… 

You can’t move these days for articles about climate change, global warming and environmental disasters. All this talk about impending doom and gloom can often lull you into a detached reverie thinking “what the hell can I do about it anyway?” Although sometimes the outlook seems hopeless, scientists are stepping up a gear to understand what is happening and why humans are having such an impact on our world. In the quest to understand the effects we are having on the planet, new research has drawn up a list of nine key factors and processes likely to change the Earth’s climate most dramatically. It is hoped that once we understand how these processes work, and how long we have until the point of no return, action could be taken to allow the climate to heal.

Prof. Tim Lenton from the University of East Anglia, UK, has identified when the tipping points are likely to occur for the nine key geological factors, and the next one is most likely going to be the collapse of the Indian summer monsoon, which is variable at best. The list is as follows (plus predicted time to tipping point):

• Arctic sea-ice melt (approx 10 years)
• Greenland ice sheet decay (more than 300 years)
• West Antarctic ice sheet decay (more than 300 years)
• Atlantic thermohaline circulation collapse (approx 100 years)
• El Nino Southern Oscillation increase (approx 100 years)
• Indian summer monsoon collapse (approx 1 year)
• Sahara/Sahel greening and West African monsoon disruption (approx 10 years)
• Amazon rainforest dieback (approx 50 years)
• Boreal Forest dieback (approx 50 years)

Many of the factors seem obvious. The melting of the Arctic ice for instance will cause a global rise in sea levels and a loss of ice cover causing Earth’s albedo to decrease (reflectivity decreases), amplifying the greenhouse effect. Also, El Nino in the South Pacific will occur more often, causing rapid and extreme changes in the large-scale weather structure; hurricanes, flooding, droughts and unseasonal shifts in the jet stream will become more and more common.

Some of the factors are perhaps less obvious. For instance, the collapse of the Atlantic thermohaline circulation would have a counter-intuitive effect on the north Atlantic, actually cooling the waters around Europe, North America and the Arctic. The thermohaline drives the circulation of the oceans, so should the Atlantic thermohaline collapse, water from the equator will stop drifting north, providing the warmth at such high latitudes. This effect is unlikely to slow the melting of the Arctic ice-sheets, but it will have devastating effects on biodiversity in the region.

“Society must not be lulled into a false sense of security by smooth projections of global change […] Our findings suggest that a variety of tipping elements could reach their critical point within this century under human-induced climate change. The greatest threats are tipping of the Arctic sea-ice and the Greenland ice sheet, and at least five other elements could surprise us by exhibiting a nearby tipping point.” – Prof Lenton

Although worrying, many of the tipping point projections could be averted should strong action be taken by the international community and individuals alike – after all, we can all contribute in some way.

Source: Telegraph.co.uk