Posted on by Fraser Cain

Distance to the Center of the Earth

The Earths interior (University of Chicago)

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The average distance to the centre of the Earth is 6,371 km or 3,959 miles. In other words, if you could dig a hole 6,371 km, you’d reach the center of the Earth. At this point you’d be in the Earth’s liquid metal core.

I said that this number is an average. That’s because the Earth isn’t a perfect sphere, it’s actually an oblate spheroid – a squished ball. The Earth is rotating on its axis, turning around once a day. Points on the equator are moving in a circle more than 1,600 km/hour. This creates a centrifugal force that pulls regions of the equator outward and flattens the poles.

The distance to the center of the Earth from the equator is 6,378 km or 3,963 miles. And the distance to the center of the Earth from the poles is only 6,356 km or 3,949 miles. That’s a difference of 22 km. In other words, if you’re standing on the equator, you’re 22 km further away from the center of the Earth than someone standing on the North Pole.

So if you did want to dig that hole into the Earth, the shortest distance would be from the North or South Pole. Good luck!

We’ve written several articles about the center of Earth. Here’s an article about the radius of the Earth, and here’s an article about the layers of the Earth.

If you’d like more info about the interior of the Earth, check out this article from the University of Nevada, Reno.

We’ve recorded an entire episode of Astronomy Cast about the Earth. Listen here, Episode 51: Earth.

Posted on by Fraser Cain

Earth Surface Temperature

Sea temperature model

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The average Earth surface temperature is 14° C. That’s 287 kelvin, or 57.2° F.

As you probably realize, that number is just an average. The Earth’s temperature can be much higher or lower than this temperature. In the hottest places of the planet, in the deserts near the equator, the temperature on Earth can get as high as 57.7° C. And then in the coldest place, at the south pole in Antarctica, the temperature can dip down to -89° C.

The reason the average temperature on Earth is so high is because of the atmosphere. This acts like a blanket, trapping infrared radiation close to the planet and warming it up. Without the atmosphere, the temperature on Earth would be more like the Moon, which rises to 116° C in the day, and then dips down to -173° C at night.

We’ve written several articles about the temperature of the planets. Here’s an article about the temperature of all the planets, and here’s an article about the temperature of the Moon.

If you’d like more information on the Earth, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an entire episode of Astronomy Cast all about Earth. Listen here, Episode 51: Earth.

Posted on by Nancy Atkinson

Deep, Fiery Undersea Volcano Captured on Video

The orange glow of magma is visible on the left of the sulfur-laden plume. The area shown in this image is approximately six feet across in an eruptive area approximately the length of a football field that runs along the summit. (Image courtesy of NSF, NOAA, and WHOI Advanced Imaging and Visualization Lab)

Ever seen fire and smoke under water before? Oceanographers using a remotely operated underwater vehicle discovered and recorded the first video and still images of the deepest underwater volcano actively erupting molten lava on the seafloor. The ROV Jason vehicle captured the powerful event nearly 1.2 km (4,000 feet) below the surface of the Pacific Ocean, in the “Ring of Fire” region, near Fiji, Tonga and Samoa. “It was very exciting. We’ve never seen anything like that on the ocean floor,” said Bob Embley, a marine geologist with NOAA, who described the event an underwater Fourth of July. “When we started to see red flashes of light, everyone was extremely excited. Then we had to get down to the work of actually understanding of what we were seeing.”

The scientists presented their findings, along with HD video at the American Geophysical Union’s fall meetings in San Fransciso. The video was taken in May of 2009, and the science team said the undersea volcano is likely to still be erupting, and may have started activity in late 2008.

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Embly said the eruption couldn’t be seen above the water, but there were “water column anomlies which indicated an eruption going on. We knew within a few hundred feet where the eruption was taking place.”

There were actually two erupting regions, but the video shows the most dramatic one. Visible in the video is magma – sometimes fiery, red hot at 1,371 C (2,500 degrees F) – bursting up through the seawater, with fragments of rock being propelled and magma flowing down the slope of the volcano. Hot sulfer “smoke” plumes can also be seen.

The volcano is spewing a type of lava known as Boninite, which until now had only been seen in extinct volcanoes more than a million years old.

A underwater “hydrophone” recorded the sound, and it was synched with the video.

The ROV Jason is designed and operated by the Woods Hole Oceanographic Institution for the National Deep Submergence Facility.

Samples collected near the volcano showed the seawater to be highly acidic, similar to battery or stomach acid, the researchers said. Despite the harsh conditions, scientists found and photographed a species of shrimp apparently thriving near the volcanic vents.

“Nobody would have predicted that things would have survived long enough in water that acidic. It seems like it’s too harsh a condition,” said University of Washington chemical oceanographer Joseph Resing.

They hope to go back in a few months and see all the other creatures that have taken up residence there.

Sources: WHOI, NOAA, NSF, AGU press conference

Posted on by Nancy Atkinson

Earth’s Atmosphere Came from Outer Space

A new study from the University of Heidelberg suggests that flash-heating and carbon depletion could have been intrinsic to the emergence and evolution of life on Earth. Credit: NASA

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A new study finds the gases which formed the Earth’s atmosphere – as well as its oceans – did not come from inside the Earth but from comets and meteorites hitting Earth during the Late Heavy Bombardment period. A research team tested volcanic gases to uncover the new evidence. “We found a clear meteorite signature in volcanic gases,” said Dr. Greg Holland the project’s lead scientist. “From that we now know that the volcanic gases could not have contributed in any significant way to the Earth’s atmosphere. Therefore the atmosphere and oceans must have come from somewhere else, possibly from a late bombardment of gas and water rich materials similar to comets.”

Holland said textbook images of ancient Earth with huge volcanoes spewing gas into the atmosphere will have to be rethought.

According to the theory of the Late Heavy Bombardment, the inner solar system was pounded by a sudden rain of solar system debris only 700 million years after it formed, which likely had monumental effects on the nascent Earth. So far, the evidence for this event comes primarily from the dating of lunar samples, which indicates that most impact melt rocks formed in this very narrow interval of time. But this new research on the origin of Earth’s atmosphere may lend credence to this theory as well.

The researchers analyzed the krypton and xenon found in upper-mantle gases leaking from the Bravo Dome gas field in New Mexico. They found that the two noble gases have isotopic signatures characteristic of early Solar System material similar to me teorites instead of the modern atmosphere and oceans. It therefore appears that noble gases trapped within the young Earth did not contribute to Earth’s later atmosphere.
The study is also the first to establish the precise composition of the Krypton present in the Earth’s mantle.

“Until now, no one has had instruments capable of looking for these subtle signatures in samples from inside the Earth – but now we can do exactly that,” said Holland.

The team’s research, “Meteorite Kr in Earth’s Mantle Suggests a Late Accretionary Source for the Atmosphere” was published in the journal Science.

Sources: Science, EurekAlert

Posted on by Fraser Cain

Earth’s Mass

Blue Marble Earth

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The Earth’s mass is 5.9736 x 1024 kg. That’s a big number, so let’s write it out in full: 5,973,600,000,000,000,000,000,000 kg. You could also say the Earth’s mass is 5.9 sextillion tonnes. Phew, that’s a lot of mass.

That sounds like a lot, and it is, but the Earth has a fraction of the mass of some other objects in the Solar System. The Sun has 333,000 times more mass than the Earth. And Jupiter has 318 times more mass. But then there are some less massive objects too. Mars has only 11% the mass of the Earth.

Because of its high mass for its size, Earth actually has the highest density of all the planets in the Solar System. The density of Earth is 5.52 grams per cubic centimeter. The high density comes from the Earth’s metallic core, which is surrounded by the rocky mantle. Less dense planets, like Jupiter, are just made up of gases like hydrogen.

We’ve written several articles about the mass of planets in the Solar System. Here’s an article about the mass of Mercury, and here’s an article about the mass of the Sun.

If you’d like more information on the Earth mass, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about the Earth. Listen here, Episode 51: Earth.

Posted on by Abby Cessna

Tallest Mountains

Olympus Mons. Image credit: NASA/JPL

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There are many tall mountains around the world as well as on other worlds. Mount Everest is the highest mountain in the world at 8,848 meters. Mauna Kea is the tallest mountain in the world. The tallest mountain is measured from base to top while the highest mountain is measured from sea level to the top.  Everest is located in the Himalayan mountain range in Nepal and near Tibet. Mauna Kea is located in Hawaii and is 10,200 meters from base to tip. From sea level though, it is only about 4,205 meters tall.  Mauna Kea is an extinct shield volcano.

These are not the only tall mountains though. K2 is in the Karakoram mountain range on the border of Pakistan and China. It is 8,612 meters tall and is generally considered the second tallest mountain in the world. The Himalayans are home to many tall mountains besides Mount Everest. This includes Mount Kangchenjunga at 8,586 meters and Mount Lhotse I at 8,501 meters.

Most of the world’s tallest mountains are located in Asia; however, there are a number of tall mountains that are located on other continents. The seven tallest mountains in different continents are known as the Seven Summits. Climbing all seven mountains is a mountaineering challenge that was started in the 1980’s.The first of these is Mount Everest. Another summit is Aconcagua, which is a mountain in Argentina in South America. At approximately 6,962 meters, it is the tallest mountain in the Americas. North America’s tallest mountain is Mount McKinley at 6,194 meters. Mount Kilimanjaro can be found in Tanzania in the continent of Africa and is 5,895 meters tall. The large summit of Mount Kilimanjaro is covered with an ice cap that is receding and according to scientists will eventually be gone. Mount Elbrus, the tallest mountain in Europe at 5,642 meters, can be found in Russia. Vinson Massif is Antarctica’s tallest mountain at 4,897 meters. It is also very large being 21 kilometers long and 13 kilometers wide.  Australia-Oceania’s largest mountain can be found in Indonesia. At 4,884 meters, it is Puncak Jaya, which is also known as the Carstensz Pyramid.

The tallest mountain that we know of is not even on Earth. It is located on Mars and is known as Olympus Mon.  A shield volcano, Olympus Mon is 27,000 meters tall. Mars is not the only other planet with tall mountains though. Venus’ Maxwell Montes is 11,000 meters tall. Satellites also have tall mountains including our Moon, which has Mons Huygens at 4,700 meters tall. The moon Io has a mountain, Boösaule Montes, which is approximately 17,000 meters tall.

Universe Today has articles on tallest mountain and tallest mountain in the Solar System.

For more information, you should take a look at what are the world’s tallest mountains and highest mountains.

Astronomy Cast has an episode on Earth you will find interesting.

Sources:
http://en.wikipedia.org/wiki/List_of_highest_mountains

Posted on by Nancy Atkinson

What If Earth Had Rings?

Earth's Rings over San Bernadino. Credit: Kevin Gill (CC BY-SA 2.0)


Here’s a video that poses — and answers — an interesting question: what would Earth look like if it had rings like Saturn? This animation was done by artist Roy Prol, and it shows not only how the rings would look from space, but also the view Earthlings would have of the rings.

 

Prol says the ring views from Earth’s surface were created according to the location’s latitude and the viewer’s orientation, and that the size of the rings was calculated respecting the Roche limit for the Earth. As you can se in the video, the rings would look different, depending on where you were on our planet. A very intriguing concept, and the video is very well done.

The only bad thing about Earth having rings is that we probably wouldn’t have our beautiful Moon.  Imagine, instead of all the songs, poems and paintings of the Moon over the past centuries, we’d have odes to our rings. 

One of our favorite image editing artists is Kevin Gill, and he’s also created imagery of Earth having rings, such as our lead image, which shows Earth’s Rings over San Bernadino, California and this one, below:

 

         

 

Earth’s Rings from New Hampshire. Credit: Kevin Gill (CC BY-SA 2.0)
Posted on by Nancy Atkinson

The Stats Are In: No Global Cooling

Global Temperature graph. Credit: National Climatic Data Center, via the Associated Press.

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The idea that the world is now cooling has been repeated in opinion columns, talk radio, pundit television and more. After a poll was released last week indicating that only 57 percent of Americans now believe there is strong scientific evidence for global warming, which is down from 77 percent in 2006, Seth Borenstein from the Associated Press decided to check out what the statistics are really saying about global warming or cooling. In a blind test, Borenstein sent accumulated ground temperature data from the past 130 years to four independent statisticians. He disguised the sources (NASA, NOAA and British meteorological data) and didn’t tell the statisticians what the numbers represented; he asked them to just look for trends in the data. The experts found no true temperature declines over time; additionally, the last ten years comprise not only the highest data set in the record, but they also have a continued, positive trend.

It seems recent weather trends have been cool — 2008 was cooler than previous years, especially the really hot years of 1998 and 2005.

Global land and ocean temperature indexes. Credit: Goddard Institute for Space Studies.
Global land and ocean temperature indexes. Credit: Goddard Institute for Space Studies.

Borenstein wanted to know if this was a longer climate trend or just weather’s normal ups and downs. All four of the statisticians agreed independently the statistics overall clearly show an upward trend of warming. Also included was a data set of satellite temperature data that is often favored by skeptics of global warming. Same story there: global temps are on the rise.

The ups and downs during the last decade, which some skeptics say show a cooling rather than warming, are variations that are repeated randomly in data as far back as 1880.

One statistician said that “cherry-picking” a micro-trend within a bigger trend is not the way to look at data.

This “blind” review of the data isn’t the only review that has shown obvious warming. Borenstein said that NOAA recently re-examined its data because of the recent “chatter” about cooling, and no cooling trend was found, and earlier this year, climate scientists in two peer-reviewed publications statistically analyzed recent years’ temperatures against claims of cooling and found them not valid.

For the full story, read Borenstein’s article here.

Source: Associated Press

Posted on by Fraser Cain

Satellite Map

NASA satellite map of the Earth

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There are thousands of satellites overhead in space right now, and many of them are being used to map every single square meter of planet Earth. And many of these images are being freely distributed on the Internet so you can access them through any browser. If you’re looking for a satellite map, there are many services out there that can help you out.

Probably the easiest and best place to start is with the Google Maps service from Google. This allows you to see a satellite map of the entire Earth. You can drag around the map to browse around the planet, and you can zoom out and in right down to the highest resolution images they have in their server. In many cases this means you can see your house, your yard, and even your car parked out in the street. You can also type in a specific address location and go straight there. There are street maps you can overlay or remove, you can get driving directions, and much more. And the Google Maps API has been made available by Google to other websites, so people are developing mashups that let you track running routes and find the nearest bathroom.

An even cooler satellite mapping service is Google Earth. Unlike Google Maps, you have to download Google Earth to your local PC, Mac or Linux machine (there’s even an iPhone version). Then you get this cool spinning 3-D version of the Earth. You can zoom out and in, type in a specific location address or geocode to find any spot on Earth. They also have a big library of additional layers that you can put over top, to see additional information mapped on the Earth. It’s well worth the download.

Another good service is TerraServer; they let you buy satellite maps if you want a nice printed version for your wall. If you don’t want to use Google, there are similar mapping tools from Microsoft and Yahoo.

We have written many articles about how satellites are being used to map the Earth. Here’s an article about how scientists use satellite photos to track penguin poop from space, and how Google’s maps had a satellite view of Obama’s inauguration.

We have also recorded an episode of Astronomy Cast all about Earth. Listen here, Episode 51: Planet Earth.

Posted on by Fraser Cain

What is the Most Remote Place on Earth?

Remotest Island

Have you had enough of kids, car alarms and the obnoxious laugh of your neighbor down the hall? You may find yourself wanting to get away from it all. If you aren’t lucky enough to have the magical nose of Sam Stephens to zap you into another dimension, you can visit Bouvet Island; an uninhabited, glacier clad island located between the southern tip of Africa and Antarctica. By all accounts, this is the remotest place on Earth, but if you don’t like the cold or have something against Norway, the county to which it belongs, take heart, you can always move to the comparatively burgeoning metropolis of Tristan da Cunha, a group of British, volcanic islands half way between South America and Africa. One of the islands in this group is actually called Inaccessible Island; and that’s saying something given its neighbors!

The most remote place on Earth can be defined as the landmass furthest from any other landmass and either inhabited or uninhabited. Since Tristan da Cunha is a group of islands, they can’t be defined as being furthest from another land mass, but taken as a whole, they tie with Bouvet Island as the most remote. The Tristan da Cunha group includes Ascension, Saint Helena and Tristan da Cunha itself which has a total population of 284. The islands are 2,816 km away from the nearest landmass.

What is Tristan da Cunha famous for, other than being hard to get to? Wideawake Airfield on Ascension Island was jointly owned by the US and British governments and used extensively during WWII, but then fell into disuse. In 1982, the British used Ascension Island as a staging base for the Falklands War. It’s famous also, for housing one of the 5 worldwide GPS ground antennae which you would no doubt, need to even get there!

Want more Earth extremes? Here’s an article about the hottest place on Earth, and here’s an article about the coldest place on Earth.

Here’s the guide to visiting Tristan da Cunha.

We have recorded an episode of Astronomy Cast all about Earth. Listen here, Episode 51: Earth.