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The animation at right, from the University of Arizona, depicts the impact that formed the Chicxulub crater in Yucatan, Mexico.

The crater measures 180 kilometers across and the impacting meteorite is estimated to be 10 kilometers wide.

The impact was so great it caused the mass extinction of the dinosaurs.

As big as it is, however, there are other craters even bigger.

The Sudbury crater in Ontario, Canada, measures 250 kilometers across. Occurring 1.85 billion years ago, the crater was formed when a comet hit the Earth.

But the largest crater is known as the Vredefort crater, located in South Africa. It measures 300 kilometers across, and the impact occurred about 2 billion years ago.

Impact craters are still being discovered; the latest may be the 36-46 kilometer wide crater found in the Congo.

This crater was revealed only after deforestation occurred in the area, and if confirmed would be one of the 25 largest impact craters in the world.

The Earth Impact Database has more information on craters around the world.

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Many articles ago we wrote that only 4,000 tigers existed in the wild.

It appears we were way off; the number is actually much lower. Conservationists now say fewer than 1,400 wild tigers exist.

Forty years ago Project Tiger started in India, which set aside 27 Tiger Reserves. Confidence ran high that this project would bring back the tiger numbers, but this is no longer true. Poaching and loss of habitat in India continue to decimate the species.

This week two tiger cubs were found dead, presumably poisoned by Indian villagers upset over a tiger killing goats. The cubs were in Ranthambore, a tiger reserve that covers several hundred square kilometers and that is visited by 200,000 tourists each year.

As of 2009, forty tigers inhabited the park. The park is surrounded by almost 100 villages, however, and the inhabitants will kill the tigers if they feel their livestock is threatened.

And, with tiger pelts fetching up to $12,500 in China, plenty of poaching still takes place. The government of India has been unable to stop the poaching. In some areas of the country continued violence and civil unrest has made it impossible for conservationists to work.

It’s hard not to be pessimistic about the situation, but it is very likely our generation will be the last to see tigers in the wild.

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The Green Man Blog is written to spread environmental awareness and appreciation of the natural world around us. Thank you for visiting! Stay green, support the organic movement, and be sure to visit www.greenmantshirts.com or www.robjuszak.com for the best in organic cotton and bamboo t shirts!

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Green Man T-Shirts in Australia? You bet!

In the southeast corner of Australia lies an area known as Gippsland, and all during the month of May they are celebrating a Be Inspired Festival. The festival will feature dozens of artists, including painters, sculptors, designers, musicians, and other performers. There will also be events held at galleries, open studios, workshops, cafes, wineries, festivals, and theatres.

In the lovely little town of Stratford, about 25 miles from the coast, a display of Green Man T-Shirts will be held at the Stratford Courthouse Art Gallery.

This is part of owner Anna Roberts’ Art-T Exhibition, featuring various t-shirt designs from around the world. During the festival, Anna will be inviting people of all ages to create a t-shirt design of their own.

Sounds like a blast to us, and we wish we could be there! But for now we’ll rely on Anna to supply us with pictures of the event, and upon the official festival website.

As we get closer to May, we’ll write more about the Be Inspired Festival, so stay tuned!

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In their book, Super Freakonomics, authors Steven D. Levitt and Stephen J. Dubner highlight a conversation with the founder of Intellectual Ventures.

Intellectual Ventures is a think-tank company, and holder of over 20,000 patents of novel ideas such as using lasers to zap malaria carrying mosquitoes, and the Salter Sink, a device that floats on the ocean and re-circulates warm surface water to deeper, colder water, which, if placed in the path of an approaching hurricane would weaken its intensity.

Nathan Myhrvold is the founder of Intellectual Ventures, and he came originally from Microsoft. He has some ideas about curbing global warming: one of them is to build an 18 mile long flexible hose to spew sulfur dioxide into the stratosphere.

Why does he think this will work? According to Myhrvold, sulfur dioxide would absorb enough water vapor to form an aerosol cloud, blanketing the Earth and producing a cooling effect. He calls this cooling blanket Budyko’s Blanket, after the Russian scientist who first suggested the idea back in the mid 1970s.

How much sulfur dioxide are we talking about here?

About 34 gallons of sulfur dioxide per minute, discharged into the stratosphere, would be enough to effectively cool the entire Northern Hemisphere. Overall, it would take 100,000 tons of sulfur dioxide per year, a fraction of the 200 million tons that is already being discharged into the environment at ground levels.

Could this actually work? Myhrvold thinks so: he’d use helium balloons to raise the 18 mile long hose high into the sky, and small pumps spaced along its length would pump the sulfur dioxide along.

Critics say the plan is insane, and we need to concentrate on curbing emissions, not on “geoengineering.” Myhrvold counters that both approaches are needed; it is too late to think curbing emissions alone will be sufficient to reduce global warming.

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Over the last 72 years, the International Whaling Commission (IWC) has established whale sanctuaries in order to protect the species from uncontrolled whaling.

In 1938, the IWC established a sanctuary in the Antarctic. Forty-one years later the Indian Ocean Sanctuary was established and in 1994 IWC adopted the Southern Ocean Sanctuary as another area in which commercial whaling is prohibited.

So why does Japan actively hunt whales in these sanctuaries?

Well, according to Japan’s interpretation of the sanctuary statutes, whaling is still allowed for “scientific research.” Therefore, Japan regularly slaughters whales in these sanctuaries and chalks it up to “research.”

Japan runs their scientific program under the acronym of JARPA, which stands for JApanese whale Research Program in the Antarctic.

Under JARPA, Japan kills over 1,000 whales annually in the Southern Ocean Sanctuary alone.

Despite worldwide condemnation, Japan continues to slaughter whales wherever it wants. In 2007, the IWC issued Resolution 2007-1 that contained the wording, “the aims of JARPA II do not address critically important research needs.” In bureaucratic-speak, that’s about as strong as language can get when calling a country a liar.

Yet, despite being called out by the IWC on its ridiculous research claims, Japan refuses to stop its whale slaughter.

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Are the big trees in world-famous Yosemite disappearing? One study suggests they are.

Scientists from the US Geological Survey studied large tree density data from the 1930s and 1990s. The result? The density of big trees has fallen by 24%. In the 1930s, there were 45 big trees per hectare. By the 1990s there were only 34.

This is surprising, since these larger trees have survived hundreds of years through wet and dry periods, fires, climate changes, and insect infestations. Smaller trees can succumb to these perils, but once they grow big their ability to survive increases. So why should the big trees be dying out now?

Scientists aren’t sure what the exact reasons are, but if the big trees are thinning out in a protected park like Yosemite they surely are thinning out in other areas as well.

Big trees play an important role in forest ecosystems, moderating the forest environment with their huge canopies and providing unique habitats for a number of other plants and animals.

A significant change in big tree density could mean further drastic changes in the entire forest ecosystem.