Tag: Terra

Nearly iceless Iceland and an icy island

By Phil Plait | October 12, 2012 7:00 am

Sometimes, you have to leave a planet to appreciate it.

I love pictures of Earth from space. They provide a perspective you just cannot get from the ground, or even from the air. For example, have you ever seen a nearly iceless Iceland?

[Click to enbjörkenate.]

This picture was taken by the European Space Agency’s Envisat satellite in July 2010 and is a rare shot of the island nation completely cloud-free. Since it was summer it’s nearly ice free as well, though you can see glaciers dominating some parts of the landscape (contrast this with one of my all-time favorite pictures of Earth from space, also of Iceland).

The blue-green swirls to the north are phytoplankton blooms – another favorite of mine when seen from space.

Half a planet away is another island, far smaller, that was also cloudless but this time encased in ice: South Gerogia Island off the coasts of South America and Antarctica, seen by the Terra satellite:

This picture was taken in late September, 2012, and the island is locked in by ice. You can see large icebergs floating nearby too. To give a sense of scale, both bergs are about 35 kilometers (roughly 20 miles) across. South Georgia Island is pretty rugged, with quite a few peaks over 2000 meters high and one at nearly 3000 meters (impressive for an island only about 150 km long).

When I saw the picture, I knew I had heard of the island, and the caption at the Earth Observatory site reminded me of how I knew it: Antarctic explorer Shackleton went there with a small number of men on an ailing lifeboat after his ship Endurance was crushed by the ice of Antarctica. He left most of his crew on Elephant Island after a harrowing trek across the ice, went to South Georgia Island, hiked across those ridiculously difficult peaks, got to a whaling station and set up a rescue mission for his men… which took months to be completed.

And get this: he didn’t lose a single man. Not one.

The story of Shackleton, the Endurance, and his men, is in my opinion the single greatest tale of exploration and adventure that has ever been recorded. Even reading an abbreviated timeline will chill you. Trust me: go find a book about this, settle down in a comfortable (warm!) spot, and read it. There are instances in history where the human spirit is uncrushable, unstoppable. This is one of those times, and will inspire you.

It’s that same spirit, in fact, that put our telescopes in the sky so we can better look at ourselves.

Image credits: ESA; Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC.

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CATEGORIZED UNDER: Cool stuff, Pretty pictures

Icebergs off Greenland

By Phil Plait | July 30, 2012 7:00 am

Greenland’s been in the news lately, what with cracking off an iceberg as big as Manhattan, and having a huge burst of melting due to unusual warm air ridges squatting over it.

The Greenland ice sheet is huge: 1.7 million square kilometers (650,000 square miles), and commonly creates a lot of icebergs in the summer. This season is no exception, and in mid-July, during the biggest melt ever seen, In 2005, NASA’s Terra Earth-observing satellite took this quite beautiful shot of icebergs floating off Greenland in Baffin Bay: [NOTE: My mistake, I thought this was a recent pic, but it’s actually from 2005! Oops. I somehow missed that, and thanks to r721 in the comments for pointing it out. I’ll note I saw this picture before all the Greenland melting news, and was going to post it simply because it was beautiful! Then all the other news came out, and so I waited to post it. Sorry about the error, and I’ll add that this doesn’t change anything I wrote here except for the part I struck through above about timing.]

[Click to hugely englacienate.]

Note the scale; the image is about 45 km (27 miles) on a side. The image is a mix of natural colors and infrared; that makes the water look deep blue, the ground brown, and vegetation red (the Greenland coast has grass and other plants). The icebergs are easy enough to spot, some are several hundred meters across. The smaller ones pose the biggest navigational hazard, and images like this (as well as spotters on the sea and in the air) help seafarers avoid the worst of them.

And one thing I want to note. Last week I wrote about the Greenland ice melt in July, and as usual got some, um, interesting comments about it. I was very careful when talking about the Greenland melting and not tie it to global warming; I start the paragraph saying it’s difficult to pin any specific event with climate change, and end with saying the melting is consistent with what we expect. I even mention the fact that some of the melting is probably due to historic cycles, yet many people made comments as if they hadn’t read that particular statement. It’s amazing to me. It shows the state of the "debate" now; it doesn’t matter how careful I am and what pains I take to be accurate. The attacks blow through as if – oddly enough – facts don’t matter.

It would be so much easier if I could just make things up out of thin (but hot) air, find some small niggling point to amplify well beyond what’s called for, to bend facts like moldable plastic to fit whatever preconceived ideology I have.

But when it comes to things like this, I have no ideology. Seriously. I would love for global warming to not be true. I would love it if the facts indeed showed our climate is stable, or that the change is natural, or that the change won’t have any deleterious effects.

Alas, that’s not the case. Reality is, in the end, real. As is global warming, and the sooner we get past the political noise about it, the better.

Image credit: NASA/JPL

Related Posts:

Greenland seeing unprecedented melting
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Five shots against global warming denialism
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The scars of a Colorado fire

By Phil Plait | July 29, 2012 7:15 am

A few weeks ago, Colorado fires raged. They are still there, but mostly out and contained – the Boulder fire is completely contained, but pockets of fire will probably burn at a low level for weeks and be put out as they’re found.

South of us, in Colorado Springs, the wildfire was apocalyptic. It destroyed over 18,000 acres (72 square kilometers, 28 square miles) and many buildings and houses. The scar it left behind is visible even from space, especially in the infrared, as in this image from the Earth-observing Terra satellite:

[Click to conflagrate.]

The way this image is color-coded, ironically vegetation looks red while fire-ravaged areas are greenish. The scale bar at the lower left should give you a sense of how big this fire was. Most of the houses destroyed were in the Mountain Shadows subdivision, which is labeled. A vast amount of effort by firefighters went in to making sure the fire didn’t progress farther down the slope of the foothills.

Images like this one can help people assess the extent of fire damage. And they serve as a reminder that our environment can be tragically fragile. To some extent it’s a natural process – this fire, along with the one in Boulder and the huge one west of Fort Collins were all started by lightning during thunderstorms. But our presence changes some of these processes, and we make some things better and others worse. The more we understand how fires start, how they spread, and how to stop them, the better. Watching all three fires both from the ground (in the case of the Boulder fire, in person as well) and from space is something I’d prefer not to have to do again.

Image credit: NASA Earth Observatory image by Jesse Allen and Robert Simmon using data from the NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

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CATEGORIZED UNDER: Miscellaneous, Pretty pictures

An ear to the ocean

By Phil Plait | February 11, 2012 7:06 am

The Terra satellite is designed to study our planet from space, examining the environment over large scales and in high resolution. While passing over south Africa it took this seemingly normal — if still very beautiful — image:

I rotated it, so north is to the left. You can see land to the left, the southernmost tip of Africa, called Cape Agulhas. To the top is the Indian ocean, with the Atlantic to the right. A weather system is forming there, and all looks as it should… until your gaze settles all the way to the right (south). Wait… what’s the blue swirly thing?

Holy otology! Is that a giant ear?

Nope. It’s an eddy, a vortex, in the ocean, probably spun off the ocean current that flows around the southern cape of Africa. These eddies can dredge up material from deeper waters, including nutrients. Phytoplankton in the water feeds of those nutrients, and bang! Plankton bloom.

The plankton flows along with the water, coloring it blue, making it stand out eerily against the water. As I pointed out in an earlier post about these blooms, we can learn a lot about the environment from them. Plankton are sensitive to climate change, for example, and can act as indicators of the water’s physical characteristics.

When I see an image like this I think of all the funding cutbacks NASA is facing right now — and yeah, I’ll be writing about that soon. Our planet is on a cusp right now, and I can’t help but fret about the opportunities we might miss if we step back from space. Exploring space, even just being in space, has given us a perspective on our home world we couldn’t possibly have achieved otherwise. Some things, once begun, shouldn’t be stopped. Try as they might, some politicians can’t make us unsee what we’ve seen, and unlearn what we’ve learned.

Unless we let them, of course. I won’t, and I hope you won’t either. Let the picture above serve as a reminder: when it comes to keeping track of the Earth, we have to keep our eyes and ears open.

Related posts:

Stunning view of a bloom from space
Phytoplankton bloom
Titanic’s revenge

The topographic Earth

By Phil Plait | October 18, 2011 1:30 pm

This is pretty nifty: a new elevation map of the Earth has just been released by NASA and Japan. It’s a "significantly improved" version of one that came out in 2009.

It uses Japan’s ASTER, the Advanced Spaceborne Thermal Emission and Reflection Radiometer, an instrument on board NASA’s Terra satellite. Terra is an Earth-observer, with detectors on board used to study various properties of our planet. ASTER looks both straight down and slightly behind the satellite’s track on the Earth is it passes. Over time stereo image pairs are created, and these can be used to create very high-resolution elevation maps (called topographic maps) of the surface of the Earth.

The new images are higher-res than before, and cover the Earth better to the tune of 260,000 more images. As an example of what can be done, they used it to make this map of the Grand Canyon:

[Click to enmesanate.]

One thing that struck me as funny when I read it: the coverage of ASTER’s observations goes from the Equator to as far north and south as 83° latitude… and they say that this is 99% of the Earth! That sounds odd, doesn’t it? You’d think the north and south poles of the Earth from 90° to 83° would be more than that, but in fact it’s true.

The portion of a sphere above a certain latitude line is called a cap, and the area of that cap depends on the latitude in question, and the radius of the sphere. I drew myself a diagram, fiddled with the numbers a bit, and found that the area of the Earth north of 83° compared to the surface area of the northern hemisphere is about 0.75%! So in fact, ASTER covered a bit more than 99% of the Earth’s surface, even if it never got past that 83°latitude.

Math! Surprising people since the time of Pythagoras.

Anyway, if you want to download the ASTER data yourself, you can: it’s public. Japan has a copy, and so does the USGS. I imagine it won’t be long before it’s integrated into Google Earth and all that too. Living in the future is pretty cool.

Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

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CATEGORIZED UNDER: Cool stuff, NASA, Pretty pictures

Titanic's revenge

By Phil Plait | September 9, 2011 7:00 am

About a year ago, an enormous iceberg split off the Petermann glacier in Greenland. Taken by the current, it headed south, and just last month was off the coast of Labrador. The iceberg was over 20 km (12 miles) long.

On August 22, NASA’s Terra satellite took a look at it and saw this:

I have nothing much to add here, except to make sure you understand that a chunk of ice significantly bigger than Manhattan Island broke in half.

Ships aren’t alive, and even if they were the existence of their souls would be in doubt. But still, the idea appeals to me that somewhere, somehow, the Titanic is laughing.

Image credit: Jeff Schmaltz, MODIS Rapid Response, NASA Goddard Space Flight Center.

Related posts:

Enormous glacier calves in largest arctic event seen in 48 years
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Titanic iceberg headed for Australia
Dramatic glacial retreat caught by NASA satellite

CATEGORIZED UNDER: Cool stuff, Pretty pictures

A long, thin, volcanic plume from space

By Phil Plait | July 15, 2011 7:00 am

In Chile, the volcano Puyehue-Cordón explosively erupted in June, sending thick layers of ash to the east over the country and into Argentina. While the activity has died down, an ash plume still flows from the stratovolcano, and was spotted by NASA’s Terra satellite on July 8:

Chile is on the left, Argentina on the right. The image shows a region over 400 km (240 miles) across, giving you an idea of just how long that plume is… and see all that beige covering Argentina? That’s ash. As the wind has shifted the plume has changed direction, covering vast swaths of land with volcanic ash.

NASA’s Earth Observatory has several spectacular images of the eruption seen from space, and The Big Picture has them from the ground.

Credit: NASA images courtesy Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center

I’ve collected quite a few images of volcanoes from space into a gallery slideshow. Click the thumbnail picture to get a bigger picture and more information, and scroll through the gallery using the left and right arrows.]


CATEGORIZED UNDER: Pretty pictures

Staring down an active volcano's throat

By Phil Plait | June 28, 2011 6:02 am

I have seen some amazing volcano pictures in my time, but this one just released by NASA is way, way up on the list of pure, freaking, awesome:

[Click to hephaestenate.]

That spectacular image is from the Earth Observing-1 satellite, and shows the Nabro volcano in Eritrea, a country bordering the Red Sea on the horn of Africa. The volcano has been erupting for a couple of weeks, but its isolated location has made it difficult to get observations from the ground. The best views have been from satellites like EO-1.

This picture, taken on June 24, is false color; red is actually near-infrared, showing the intense heat generated by the lava in the caldera and flowing off to the northwest (upper left). The blue cloud is likely water vapor, and additional clouds are from gases escaping from the cooling lava. The caldera crater is obvious, and to give you a sense of the scale of this beast is about 6 km (3.6 miles) across.

Read More

CATEGORIZED UNDER: NASA, Pretty pictures, Science

Volcano followup: pix, video

By Phil Plait | May 23, 2011 2:07 pm

Within hours of posting about the eruption of the Icelandic volcano Grimsvötn, I found out that helicopter footage of the plume (with tons of lightning) has been posted on Vimeo by Jon Gustafsson:

Lightning is common in volcanic plumes, but this one produced quite a bit more than usual. The footage is striking. Ha ha.

Also, NASA released a beautiful image of the plume as seen by the Earth-observing Terra satellite:

[Click to hephaestenate.]

Note the scale; the ash column is over 20 km (12 miles) across. I said in the post earlier it reached 11 km in height; however the NASA news release states that it reached over 20 km high!

There is some indication the ash may be a threat to air travel in the UK, too. That’s a bummer; Eyjafjalajökull disrupted air travel for weeks. Let’s hope this one subsides sooner.

Video from Jon Gustafsson on Vimeo; Terra image from Jeff Schmaltz, MODIS Rapid Response Team at NASA GSFC

CATEGORIZED UNDER: Cool stuff, Pretty pictures

Happy Earth Day

By Phil Plait | April 22, 2011 8:30 am


Image credit: NASA

CATEGORIZED UNDER: Cool stuff, Pretty pictures

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