Category Archives: In the news

The Teeny-Tiny Trace of a Giant Impact

By Thomas

The Moon formed in a Giant Impact of a planet called Theia with Earth (Figure 1). You can find a nice simulation of this event at the end of this post or watch the orginal here. In a post a few weeks back I mentioned that there are some problems with the details of this theory and that I would write about that soon.

The Giant Impact

Figure 1: The Giant Impact
Source: National Geographic

As a paper published last week in Science [1] is exactly about that topic, I thought it is time to follow up on this promise. The mentioned paper shows that technology has developed far enough to allow science to tackle the problems lurking within the Giant Impact Theory. Responses in the media (e.g. here, or for german speakers here) about the paper seem to focus on the fact that the paper supports/confirms the Giant Impact Theory.

Yes, the results are in agreement with the theory and therefor support/confirm it!

But to focus on this, implies that the main question we are facing, when it comes to the Moons origin, is:

Was there a giant impact?

Of course one is allowed to ask this question. However, in science this question is only taken seriously if you`ll offer an alternative hypothesis, that works equally well or better in hindsight of the known facts. When it comes to the origin of the Moon, all other origin hypotheses have already been discarded for various reasons and to my knowledge there are no rival hypotheses to the giant impact left.1 The Giant Impact is a fact, and was one before this paper!2

The question is not: Did it happen?

The question is: How did it happen?

The Giant Impact Theory came a long way since it was first proposed in 1975 [2]. It solved a lot of problems regarding chemical similarities and differences between Earth and Moon. But in recent years it got stuck in a bottleneck.

What had happened?

Measurements of the elements oxygen, chromium, titanium, tungsten and silicon had shown that the ratios between the isotopes of those elements were the same in the Earth and the Moon. [3]

Why was that a problem?

Those ratios are fundamentally different in other rocky bodies in our solar system like the asteroids and – more important – Mars. Therefor it is likely that Theia and the Proto-Earth (the Earth before the Giant Impact) differed in these isotopic signatures as well. If that was the case, the standard model of the Giant Impact would predict that those ratios would be different in the Earth and the Moon (Figure 2).

F2.medium

Figure 2: Different Models of the Giant Impact.
Source: Science

Different changes in the model were proposed to achieve the similarity in isotopic ratios, but all of them require very special conditions, such as a fast spinning Proto-Earth or Theia being the same size as Earth (Figure 2) or complex processes following the impact [3-5].

Or maybe Theia didn`t had a similar isotopic signature to the Proto-Earth? For that line of thinking we would have to revise what we assume about the distribution of isotopic signatures in the solar system. That would be a great and enlightening thing to do, but would require samples from a rocky planet other than Mars – preferentially our twin planet Venus. [3]

So what`s the great news?

Actually, the great news are small – very small. That best describes the differences between the isotopic signatures of Earth and Moon rocks which now were uncovered.

But didn`t I said above that there were no such differences?

Indeed, but I should have added “within error”. The error is used to describe the area of uncertainty around a measured result. For example, I know I`m 185 cm tall. But I have never measured that very accurately, so it could easily be that I`m actually 1 cm taller or smaller. The 1 cm is the error on the measurement of my height. If I now meet a person who has measured his or her height (equally lax) to be 185 cm, we would have to conclude that we are equally tall (within error), even though he or she might be 186 cm and I only 184 cm. How can we find out? We have to measure more precise, let’s say with a mm-scaled tape.

In a nutshell, that is what the new study did – measured more precise. They found that when you compare 1 million oxygen atoms on Earth to 1 million oxygen atoms on the Moon, you`ll find that 123 of those atoms are different isotopes4.

This means a great relief, for some reasons:

a.) It means there is a difference in those isotopic signatures and we don`t have to invoke very special conditions5 for the Giant Impact.

b.) It promises that we`ll find similar differences in the other isotope systems apart from oxygen.6

c.) When we know how the Earth and the Moon differ, we can infer more on the nature of Theia, the Proto-Earth and the details of the impact.7

And that is much more, than just to confirm that there was a Giant Impact!

 


A simulation showing the Giant Impact.
Source: Nature


1 That doesn`t mean someone might come up with a new one in the future.

2 Imagine the media would title every article about new advances in evolutionary biology with “Evolution Confirmed!” – Technically true, but still missing the point.

3 If we`re including the error: 9-15

4 Don`t worry about the isotopes. It basically is like two boxes filled with 1 million red and blue balls, where one box has 12 more of the blue balls. Even finding that out, would be hard. Now imagine that on an atomic scale, where you can`t “see” the atoms and where the difference between the balls is the equivalent of blue and very-slightly-darker blue.

5 Special conditions are often a sign that there`s something wrong with your theory.

6 Oxygen isotopes were the first to indicate the similarity-problem [6], it`s good that they make up by showing a way out.

7 In the presented paper, the authors speculate on the basis of their data, that Theia might have had a enstatite chondrite composition, which is material we find in the asteroid belt. But we have to see what the future (and other isotopic systems) will bring.


Literature

1. Herwartz, D., et al., Identification of the giant impactor Theia in lunar rocks. Science, 2014. 344(6188): p. 1146-1150.
2. Hartman, W.K. and R.D. Davis, Satellite-Sized Planetesimals and Lunar Origin. Icarus, 1975. 24: p. 504-515.
3. Canup, R., Lunar conspiracies. Nature, Vol. 504, 2013(7478): p. 27.
4. Elkins-Tanton, L.T., Planetary science: Occam’s origin of the Moon. Nature Geoscience, 2013. 6(12): p. 996-998 (2013).
5. Clery, D., Impact Theory Gets Whacked. Science, 2013. 342(6155): p. 183-185.
6. Wiechert, U., et al., Oxygen isotopes and the moon-forming giant impact. Science, 2001. 294(5541): p. 345-348.

Mama Grizzly

By Kate Holland

An image often associated with the melting of the Arctic ice cap, is that of a polar bear standing on thin ice, exemplified in Figure 1.

060403_DomCNNL3R1

Figure 1: Special Report Global Warming.
From: Time

The melting of sea ice is forcing polar bears to spend more time inland. Venturing far from their normal habitat they are interacting and interbreeding with grizzly bears, resulting in grolar bears, pizzly bears or more fancifully known as polizzly bears (pictured in Figure 2).

Technically, the naming of hybrids should depend on the sex of the parents, where the father provides the first half of the species name and the mother provides the latter half. For example, a pizzly bear has a polar bear father and a mama grizzly. But I can imagine it would be far more difficult to determine the paternity/maternity of a hybrid species outside a zoo.

grolarbear

Figure 2: A Grolar Bear – or is it a Pizzly?
From: The Guardian

The first wild grolar was encountered back in 2006, as a hunting prize. The hunter was able to avoid jail time –-and a fine – when DNA testing by Wildlife Genetics International in British Columbia confirmed the beast was a hybrid of a polar and grizzly bear (the hunters $45,000 permit was only for bagging polar bears). Since then a number of these hybrid bears have been sighted in northern Canada.

Some might argue that interbreeding is a good solution for polar bears faced with climate change. While hybridization is not necessarily a bad thing, it’s the short time periods over which it occurs, that causes a significant drop in genetic diversity. This is damaging to both species and will more quickly push them to extinction.

Interbreeding could also be a potential risk for survival, as obviously, each bear has evolved to live in quite different ecosystems. The grizzly bear is not designed for long swims, but what if a pizzly still has a taste for seals?

Then there is the rest of the ecosystem to worry about – how does the grizzly bear ecosystem deal with a grolar bear? Will it hunt all year round or hibernate? Will the grolar bear be a super predator in its habitat and cause extinctions down the food web? Such an interesting animal could also become the target of hunting (or worse – cheesy horror movies [Polizzlynado anyone?]) as it is not yet protected by conservation laws. In order to protect both, the polar bears and the ecosystems, some out-there ‘conservationists’, have suggested moving the bears to the Antarctic.

Turn back the bears!

Perhaps such issues for many species, both old and new, wouldn’t be such a problem if WE reduced our impacts on the environment – but that’s a discussion for another day.

 

Plastic all around us

By Magda.

On this blog we have covered the topic of the marine garbage patch on several occasions (for example here, here and here) as well as how important recycling of plastic waste is. So far, most research was focussed on the influence of plastic on the marine environment, but recently several articles have drawn attention to micro-particles of plastic in lakes.

The first study to focus on this issue was conducted on the great lakes and found large amounts of micro-plastic within the lake (up to 466,000 particles/km2). The researchers attributed many of the perfectly spherical particles to the use of cosmetic products containing micro beads. Due to the small size these particles cannot be filtered and eventually will end up in our water ways.

worms

Clitellate worm (B,C) Fluorescent image of the mid-body showing fluorescent microplastic particles (white arrows) in the digestive tract. From Imhof et al., Contamination of beach sediments of a subalpine lake with microplastic particles, Current biology, 2013

And they are harmful – not only to the environment, as shown by another study conducted on Lake Garda, which found plastic in the digestion system of worms and other freshwater species, which is a starting point to introduce plastic into the food cycle and thus plastic will end up on our plates as well.

Unfortunatly micro-plastic will also form due to degradation of bigger plastic particles.

And, it doesn’t even stop there:

Micro-plastic is small and light enough to get transported by wind and has been detected in several products that we consume, including milk, honey and drinking water (found by a Swiss consumer affairs TV report). And most likely this list will get a lot longer, following more studies on this topic.

Many manufactures of cosmetic products using micro-beads (used in many toothpastes and body/facial scrub,…) have agreed to not use micro-plastic in their products from 2015. However, this will not solve the problem completely, since micro-particles of plastic are also formed by degradation of larger items.

The Amazon rainforest tipping point

By Biance

Last night I watched an interesting documentary on the Amazon rainforest dealing with the consequences of a changing climate. The documentary is part of the 6-prt TV climate series ‘Tipping points’ and investigates how the rainforest manages to deal with our shifting climate.

rainforrest

Parts of the forest show first signs of changes, with big trees dying and fewer growing as these trees need a lot of water to stay healthy. While the death of such huge trees causes a fair bit of destruction, new trees emerge in the gaps. However, these are smaller trees that need less water and grow less high. Together with deforestation, fires and more frequent draughts it is a first step towards an ecological tipping point where our rainforests could turn into savannahs.

Often rainforests are described as our lungs, as they remove carbon dioxide from the atmosphere and produce oxygen and keep our atmosphere in balance by doing so. Recently NASA found that the Amazon inhales more CO2 than it emits and the forest therefore reduces global warming. However, when dying the forests releases CO2 into the atmosphere, which is estimated to be 1.9 billion tons each year.

Deforestation and fires to clear forest for farmland has already changed the regional climate drastically in terms of rainfall patterns and distribution.
Furthermore, the climatic phenomenon of the El Nino Southern Oscillation is associated with dry conditions in Brazil and the northern Amazon and its frequency increased in the past years and is expected to further increase in the future.

This is a drastic change for nature and for humans as we rely on these forests to somehow keep our atmosphere in balance.
The rainforest stores an equivalent of about 15 years of human-caused emissions in its soil and biomass and a massive die-back could greatly accelerate climate change. About 2 billion tons of CO2 are taken out of the air each year by the rainforests photosynthesis, however, during draughts in 2005 and 2010 this process reversed with 3 billion tons of CO2 emitted by the Amazon. This caused a net 5 billion ton increase in CO2 to the atmosphere.
Our changing climate, fires and more frequent draughts in change with sudden floods are pushing the Amazon to a tipping point and we are closer than you would think, with large areas dying or being already dead. If we loose the rainforest, the climate will change drastically and nature will never be the same, as we know it now.

The A-factor

Akademik Shokalskiy stuck after weather conditions changed and sea ice closed down behind the vessel.

Akademik Shokalskiy stuck after weather conditions changed and sea ice closed down behind the vessel.

By Bianca

I just stumbled over a detailed media report about the Russian Akademik Shokalskiy that recently had to be rescued out of Antarctica’s sea ice, and have been reminded about our excursion to the continent.

Although I do agree that a lot went wrong on their expedition, and human failures played an important role, it has also be admitted that you simply can’t change the A-factor and you need to adapt to it as much as possible.

The A-factor simply stands for the Antarctic-factor and is a common saying under Antarctic expeditioners as the climate is so unpredictable and weather conditions can change quickly. Continue reading

Extreme seasons: Australia melts while the US freezes

Observed maximum temperatures for Monday, 13th January, 2014. Image from BOM.

Observed maximum temperatures for Monday, 13th January, 2014. Image from BOM.

By Claire

I’m writing this post from hot hot Canberra, Australia, in my office, in front of my desk fan. In case you didn’t pick up on it, IT’S FREAKING HOT HERE!!!

This week, a large mass of warm, desert air is slowly making its way across southern Australia, bringing as many as five consecutive days above 40°C (104°F). Here in Canberra, we are forecast to swelter through five consecutive days over 38°C (100°F). Continue reading

Science inspired art: Haiku for progress

Art!? Haikus?! What does any of this have to do with a research blog? Everything. Scientific findings can be complicated, are often dripping with jargon, and easy to overlook or ignore. Science communication is most valuable when it is easy to understand. Enter watercolour and haiku.

Johnson Future

Gregory Johnson, an oceanographer at the National Oceanic and Atmospheric Administration (NOAA) has distilled the entire International Panel on Climate Change 5th Assessment report  into 19 haikus with accompanying watercolour paintings and it is brilliant! Johnson has generated a disarming and inspiring account of the present state of our climate system. Using this creative path, he has made an otherwise daunting and dense scientific report (>2,000 pages long) into an intelligent and emotional piece of art.

Below is a slideshow of Johnson’s work.

Please visit Sightline Daily for the full article and links to pdf’s of these wonderful pieces.

I challenge you all to describe your research or profession with a simple haiku. Here is mine:

Ancient stalagmite

a window into the past

tell us your story