Compare the size of Eath to a prominence on the Sun on October 10, 2011. Credit: Ron Cottrell
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The Sun is big. And comparatively, Earth is a tiny Lilliputian. We’ve all seen images comparing the size of Earth to the Sun, but here are two images from October 10, 2011 that really bring home the size-scale of features on the Sun when compared to the size of Earth. Amateur astronomer Ron Cottrell from Oro Valley, Arizona took these images of two different features on the the Sun yesterday, overlaying the size of the Earth for reference. Both are viewed in Hydrogen- Alpha light, and the first is a fiery-looking huge prominence from the northwest limb of the Sun. Yikes!
Below, see a comparison of Earth to a current sunspot:
The Earth compared to Sunspot 1312 on 10-10-11. Credit: Ron Cottrell.
This is sunspot 1312 which has a classic sunspot shape with a core a that’s larger than the Earth.
Ron used a 40mm Coronado telescope and a webcam to capture the images. He explains the colors of the Sun in Hydrogen-Alpha, and in particular why the prominence appears fiery red:
“The red color of the prominence is very close to the color collected in the image. The yellow disk is enhanced. I actually capture the disk image in black and white and add the color. I can choose any color. The final image is a composite of two separate images. Prominences are, in general, much fainter than the bright disk. Therefore, the prominence image is captured at a slower shutter speed, e.g. 1/25 sec, compared to the disk image captured at 1/100 sec. The two images are combined in PhotoShop.”
And speaking of the Sun, activity on our closest star has been ramping up and last week a series of active regions were lined up one after the other across the upper half of the Sun. Interestingly, the Solar Dynamics Observatory was able to capture how these regions twisted and interacted with each other. The video shows activity from Sept. 28 – Oct. 2, 2011, as seen in extreme UV light. The magnetically intense active regions sported coils of arcing loops and numerous times these magnetic field lines above them can be seen connecting with the active region next door. Towards the end of the clip, a leading active region blasted out a coronal mass ejection, quickly succeeded by a blast from another active region. The disruption of the magnetic field from one likely triggered the second, a phenomenon that has been observed before by SDO.
Recent photo from the ISS showing the airglow layer
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In many of the photos that we have featured recently from astronauts aboard the International Space Station, a glowing greenish-yellow band can be seen just above Earth’s limb. I’ve been asked before what this is, so I thought I’d explain it here. This is a phenomenon known as “airglow”.
A photochemical reaction that occurs high in the atmosphere, airglow is the result of various atoms, molecules and ions that get excited (chemistry-excited, that is… not “whee!”-excited) by ultraviolet radiation from the Sun and then release that energy as visible – as well as infrared – light when they return to their “normal” state. It’s not entirely unlike glow-in-the-dark toys or paint!
This light is most visible to the crew of the ISS when it is orbiting over the night side of the planet, and thus is seen in images like the one above. It appears like a thin band because viewing the atmosphere at a shallow angle – rather than directly down through it – increases the airglow layer’s relative visibility.
Most of visible airglow comes from oxygen atoms and molecules, which glow green… as commonly seen in the aurora. Other contributing elements include sodium and nitrogen. While present in the atmosphere at all layers, the region that glows visibly is typically constrained to a narrow band 85 – 95km (53-60 miles) high. The band itself is usually about 6 – 10km (4-6 miles) wide. The reason for this is that below those heights the atoms and molecules are more concentrated and collide more readily, releasing their energy sooner, and above it the density of the atoms is too low to do much colliding at all (to put it very simply.)
There are a lot of other factors involved with airglow as well, such as temperature and altitude, as well as different kinds of airglow depending on when in the day they occur. Nightglow is not exactly the same as dayglow, and then there’s even twilightglow… one could say there’s a lot glowingon in the upper atmosphere!
The "pale blue dot" of Earth captured by Voyager 1 in Feb. 1990 (NASA/JPL)
As the number of discovered extrasolar planets grows, astronomers begin looking at the next step: finding rocky Earth-like planets. In addition, astronomers would ideally like to block out the parent star and detect some of the reflected glow from the planet’s atmosphere in an attempt to characterize the chemical makeup. But what would an “Earth-like” planet’s reflected light look like? To answer this, a new paper explores what Earth should have looked like at various points in our planet’s history.
Currently, astronomers have a good understanding on how our planet reflects light. Even before satellites were launched that could observe this directly, we could see the reflected light from our home on the moon, an effect known as “Earthshine”. The amount of light reflected depends on what’s on the surface.
The paper considers five different types of reflecting materials. Water and vegetation tend to be strong absorbers of light at visible and ultraviolet wavelengths whereas ice and deserts are highly reflective. The amount of cloud cover, which also reflects a good deal of light, is the fifth.
With the modern Earth, our planet currently reflects about 32% of all incoming light. This changes by a few percent depending on the season, depending mostly on the amount of cloud cover.
This new study also analyzes what the amount of reflected light should have been for Earth, known as its albedo, during four other historical periods: the Late Cretaceous (90 million years ago), the Late Triassic (230 My ago), the Mississippian (340 My ago), and the Late Cambrian (500 My ago).
Using simulations based on the various surface features, the team from the Instituto de Astrofísica de Canarias owned by Spain, the team reconstructed the expected amount of cloud cover for these various epochs to consider their contributions to the overall albedo.
In general, the historical periods had strikingly similar amounts of reflectiveness due to “similar ocean-land-vegitation distribution” as well as similar distributions of continents between hemispheres and most deserts in low latitudes. The exception to this, was the Late Cambrian. While the average was only slightly higher, this period varied depending on which portion of the Earth was viewed.
At that time, the original supercontinent, Pangea was in the process of breaking up. They were still clustered and almost exclusively in the southern hemisphere. The sea levels were also significantly higher meaning a larger portion of land was submerged, covered by the non-reflective water. Lastly, most of the life was still concentrated in the oceans. Since it had not yet advanced to land, it is expected that the surface was mostly rocky desert terrain which would have high reflectivity. During the times when the breaking up supercontinent was facing an observer, the albedo would jump to as much as 37% only to sink to 32% when it rotated from view.
The team suggests that such a variation may allow astronomers to determine the rotation rates of planets in the future. In an ideal situation, it may even give clues to the geographical arrangement of continents.
The aurora australis seen from the ISS on September 17, 2011. Credit: NASA.
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With all of the activity that’s been occurring on the Sun recently, the aurorae have been exceptionally bright and have created quite a show to viewers – both on Earth as well as above it!
The image above was taken over the southern Indian Ocean by astronauts aboard the International Space Station. The southern lights – a.k.a. aurora australis – glow bright green and red in the upper layers of the atmosphere, creating a dazzling aerial display. (Click here to watch a movie of this.)
Shortly after, fires can be seen on the ground as the ISS passes over Australia:
Wildfires in Australia seen from orbit. Credit: NASA.
Astronauts on the International Space Station (ISS) used a digital camera to capture several hundred photographs of the aurora australis, or “southern lights,” while passing over the Indian Ocean on September 17, 2011. You can see the flowing ribbons and rays below as the ISS passed from south of Madagascar to just north of Australia between 17:22 and 17:45 Universal Time. Solar panels and other sections of the ISS fill some of the upper right side of the photograph.
Auroras are a spectacular sign that our planet is electrically and magnetically connected to the Sun. These light shows are provoked by energy from the Sun and fueled by electrically charged particles trapped in Earth’s magnetic field, or magnetosphere. In this case, the space around Earth was stirred up by an explosion of hot, ionized gas from the Sun — a coronal mass ejection — that left the Sun on September 14, 2011.
In the second image above, and in the last frames of the movie, light from the ground replaces the light show in the sky. Wildfires and perhaps some intentionally set agricultural fires burn on the continent of Australia,with smoke plumes faintly visible in the night sky. A gold and green halo of atmospheric airglow hangs above the horizon in the distance.
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Airglow is created by particles in the upper atmosphere that have been charged by UV light from the Sun during the day releasing the energy at night as greenish-yellow visible light.
Fires on the ground, fires in the sky… the stars blazing all around, the Sun in its full glory and a never-ending view of our entire planet… what an incredible place the ISS must be to work in! Absolutely amazing!
And the skies of night were alive with light, with a throbbing, thrilling flame; Amber and rose and violet, opal and gold it came. It swept the sky like a giant scythe, it quivered back to a wedge; Argently bright, it cleft the night with a wavy golden edge.
— “The Ballad of the Northern Lights”, Robert Service
This picture shows the illuminated man-made border between India and Pakistan,the line snaking through the landscape, as seen from the International Space Station on August 21, 2011. Of the hundreds of clusters lights, the largest are the capital cities of Islamabad, Pakistan, and New Delhi, India. Credit: NASA/Ron Garan
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There is an oft-repeated and perhaps beautiful saying that you can’t see political borders from space. Well, it turns out that saying isn’t true; not anymore. ISS astronaut Ron Garan took this image recently which clearly shows the border between India and Pakistan. Since 2003, India has illuminated the border with Pakistan by floodlights in attempt to prevent ammunition trafficking and the infiltration of terrorists.
“Since the beginning of human spaceflight fifty years ago, astronauts have reflected on how peaceful, beautiful, and fragile the Earth looks from space,” Garan wrote on his Fragile Oasis blog. “These reflections are not clichés that astronauts say because it feels good. It is truly moving to look at the Earth from space.”
But seeing this clearly visible political border was sobering for Garan and his crewmates.
“Realizing what this picture depicted had a big impact on me,” he said. “When viewed from space, Earth almost always looks beautiful and peaceful. However, this picture is an example of man-made changes to the landscape in response to a threat, clearly visible from space. This was a big surprise to me.”
Garan added, however, that the point here is not that we can look down at the Earth and see a man-made border between India and Pakistan. “The point is that we can look down at that same area and feel empathy for the struggles that all people face,” he said. “We can look down and realize that we are all riding through the Universe together on this spaceship we call Earth, that we are all interconnected, that we are all in this together, that we are all family.”
Garan said he believes our world is a place where possibilities are limited only by our imagination and our will to act. “It is within our power to eliminate the suffering and poverty that exist on our planet,” he said.
As an April Fool’s joke in 1978, Australian businessman Dick Smith claimed he was towing an iceberg from Antarctica to Sydney Harbour. He used a barge covered with white plastic and fire extinguisher foam in effort to convince those who gathered at the harbor to see it. Apparently, however, the idea is not such a joke after all. A team of engineers from France have studied the concept, did a simulation and found that icebergs floating around in the ocean could be tethered and towed to places that are experiencing a severe drought and water shortages.
The idea originally was conceived in the 1970’s by an graduate student named Georges Mougin, who even received some funds from a Saudi prince to test the idea, but not much came of it.
According to an article on PhysOrg, the French engineers looked into the idea and concluded that towing an iceberg from, for example, the waters around Newfoundland to the Canary Islands off the northwest coast of Africa, could be done, and would take just under five months when towed by a tugboat outfitted with a kite sail, traveling at about one knot.
The cost would be almost ten million dollars, however.
According to a simulated test, the iceberg would lose only 38 percent of its seven ton mass during the trip, if it was fitted with an insulated skirt.
Apparently Mougin is encouraged by the results and now at age 86 is trying to raise money for an actual iceberg-tow.
An iceberg the size of Manhattan drifts off the coast of Labrador
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Taken by NASA astronaut and Expedition 27 flight engineer Ron Garan, this image shows the Petermann Ice Island (PII-A) currently adrift off the coast of Labrador. The island is a chunk of ice that broke off the Petermann Glacier in Greenland in August of 2010 and has been moving slowly southward ever since. It is currently about 21 square miles (55 square km) in size – nearly the same area as Manhattan!
Garan’s original photo was posted to his Twitter feed earlier today… I cropped the full-size version, rotated it so that south is down and edited it to bring out surface details in the island. Ridges in its surface can be seen as well as many bright blue meltwater ponds.
"Another look at that lonely iceberg from space... can you find it?" @Astro_Ron
Overlaid on the left side is an approximate scale size of Manhattan. This thing is BIG!
PII-A is currently drifting toward Newfoundland but is unlikely to reach land… its base will run against the sea floor long before that. But it has been reported to be posing a problem for ships and offshore oil rigs. (Read more about PII-A on NASA’s Earth Observatory site here.)
When he’s not performing other duties aboard the Space Station, Ron Garan posts photos of Earth from orbit on his Twitter feed (@Astro_Ron) and also on his website FragileOasis.org, thereby sharing his unique and privileged perspective on our world. Founded by Garan, Fragile Oasis is a site that supports and publicizes many global projects supporting humanitarian and environmental missions. Visit, become a member, and you too can “learn, act, and make a difference.” After all, who better than an astronaut would know how much our world is connected, and how fragile it really is!
Image credit: NASA / Ron Garan. Edited by Jason Major.
PS: If you want an idea of how something like this would look like up close, check out this video below taken from a ship near one of the smaller pieces of the ice island!
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Jason Major is a graphic designer, photo enthusiast and space blogger. Visit his website Lights in the Dark and follow him on Twitter @JPMajor or on Facebook for the most up-to-date astronomy awesomeness!
It starts out innocently enough: a small speck against a field of background stars, barely noticeable in the image data. But… it’s a speck that wasn’t there before. Subsequent images confirm its existence – there’s something out there. Something bright, something large, and it’s moving through our solar system very quickly. The faint blur indicates that it’s a comet, an icy visitor from the outermost reaches of the solar system. And it’s headed straight toward Earth.
Exhaustive calculations are run and re-run. Computer simulations are executed. All possibilities are taken into consideration, and yet there’s no alternative to be found; our world will face a close encounter with a comet in mere months’ time. Phone calls are made, a flurry of electronic messages fly between computer terminals across the world, consultations are held with top experts in the field. We are unprepared… what can we do? What does this mean for civilization as we know it? What will this speeding icy bullet from outer space do to our planet?
The answer? Nothing.
Nothing at all. In fact, it probably won’t even be very interesting to look at – if you can even find it when it passes by.
(Sorry for the let-down.)
There’s been a lot of buzz in the past several months regarding Comet Elenin, a.k.a. C/2010 X1, which was discovered by Russian astronomer Leonid Elenin on December 10, 2010. Elenin spotted the comet using a telescope in New Mexico remotely from his location in Lyubertsy, Russia. At that time it was about 647 million kilometers (401 million miles) from Earth… in the time since it has closed the distance considerably, and is now around 270 million km away. Elenin is a long-period comet, which means it has a rather large orbit around the Sun… it comes in from a vast distance, swings around the Sun and heads back out to the depths of the solar system – a round trip lasting over 10,000 years. During its current trip it will pass by Earth on October 16, coming as close as 35 million km (22 million miles).
Elenin's orbit via the JPL Small-Body Database Browser
Yes, 22 million miles.
That’s pretty far.
Way too far for us to be affected by anything a comet has to offer. Especially a not-particularly-large comet like Elenin.
Some of the doomy-gloomy internet sites have been mentioning the size of Elenin as being 80,000 km across. This is a scary, exaggerated number that may be referring to the size of Elenin’s coma – a hazy cloud of icy particles that surrounds a much, much smaller nucleus. The coma can be extensive but is insubstantial; it’s akin to icy cigarette smoke. Less than that, in fact… a comet’s coma and tail are even more of a vacuum than can be reproduced in a lab on Earth! In reality most comets have a nucleus smaller than 10km…that’s less than a billionth the mass of Earth (and a far cry from 80,000 km.) We have no reason to think that Elenin is any larger than this – it’s most likely smaller.
Ok, but how about the gravitational and/or magnetic effect of a comet passing by Earth? That’s surely got to do something, right? To Earth’s crust, or the tides? For the answer to that, I will refer to Don Yeomans, a researcher at NASA’s Near-Earth Object Program Office at JPL:
“Comet Elenin will not only be far away, it is also on the small side for comets. And comets are not the most densely-packed objects out there. They usually have the density of something akin to loosely packed icy dirt,” said Yeomans. “So you’ve got a modest-sized icy dirtball that is getting no closer than 35 million kilometers. It will have an immeasurably miniscule influence on our planet. By comparison, my subcompact automobile exerts a greater influence on the ocean’s tides than comet Elenin ever will.”
“It will have an immeasurably miniscule influence on our planet. By comparison, my subcompact automobile exerts a greater influence on the ocean’s tides than comet Elenin ever will.”
– Don Yeomans, NASA / JPL
And as far as the effect from Elenin’s magnetic field goes… well, there is no effect. Elenin, like all comets, doesn’t have a magnetic field. Not much else to say there.
But the claims surrounding Elenin have gone much further toward the absurd. That it’s going to encounter another object and change course to one that will cause it to impact Earth, or that it’s not a comet at all but actually a planet – Nibiru, perhaps? – and is on a collision course with our own. Or (and I particularly like this one) that alien spaceships are trailing Elenin in such a way as to remain undetected until it’s too late and then they’ll take over Earth, stealing our water and natural resources and turning us all into slaves and/or space munchies… or however the stories go. (Of course the government and NASA and Al Gore and Al Gore’s hamster are all in cahoots and are withholding this information from the rest of us. That’s a given.) These stories are all just that – stories – and have not a shred of science to them, other than a heaping dose of science fiction.
“We live in nervous times, and conspiracy theories and predictions of disaster are more popular than ever. I like to use the word cosmophobia for this growing fear of astronomical objects and phenomena, which periodically runs amuck on the Internet. Ironically, in pre-scientific times, comets were often thought to be harbingers of disaster, mostly because they seemed to arrive unpredictably – unlike the movements of the planets and stars, which could be tracked on a daily and yearly basis.”
– David Morrison, planetary astronomer and senior scientist at NASA’s Ames Research Center
The bottom line is this: Comet C/2010 X1 Elenin is coming, and it will pass by Earth at an extremely safe distance – 100 times the distance from Earth to the Moon. It will not be changing direction between now and then, it will not exert any gravitational effect on Earth, its magnetic field is nonexistent and there are no Star Destroyers cruising in its wake. The biggest effect it will have on Earth is what we are able to learn about it as it passes – after all, it is a visitor from the far reaches of our solar system and we won’t be seeing it again for a very, very long time.
I’m sure we’ll have found something else to be worried about long before then.
“This intrepid little traveler will offer astronomers a chance to study a relatively young comet that came here from well beyond our solar system’s planetary region. After a short while, it will be headed back out again, and we will not see or hear from Elenin for thousands of years. That’s pretty cool.”
– Don Yeomans
For more information about Elenin, check out this JPL news release featuring Don Yeomans, and there’s a special public issue of Astronomy Beat, a newsletter from the Astronomical Society of the Pacific, that features David Morrison of NASA’s Ames Research Center discussing many of the misconceptions about Elenin.
An updated chart of Elenin’s orbit and statistics can be viewed here.
Australia and Asia region of Earth's geoid. Credits: ESA/HPF/DLR, anaglyph by Nathanial Burton-Bradford.
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Grab your red/cyan 3-D glasses and take a look at these marvelous new anaglyphs created by Nathanial Burton-Bradford from the latest data from GOCE satellite, showing Earth’s gravity field – or geoid. The geoid is essentially a map of the shape our world would be its surface were covered by water and if gravity were the only thing shaping this global ocean’s surface. These exaggerated views (the surface in the images of the geoid is amplified by a factor 7,000) show the most accurate model of how gravity varies across the planet. Nathanial was able to obtain high-resolution video from Dr. Rune Floberghagen of the GOCE team from which he extracted appropriate frames in order to construct hi-res anaglyph images of numerous longitudes across the globe.
In our previous article about GOCE (Gravity Field and Steady-State Ocean Circulation Explorer), we showed the entire globe and how it looks like a spinning potato. Nathanial’s anaglyphs show close-ups of various parts of the globe. Above is Australia and Asia. Take a trip around the GOCE geoid 3-D world below. Remember, use the red/cyan 3-D glasses to get the full effect!
GOCE view of South America. Credits: ESA/HPF/DLR, anaglyph by Nathanial Burton-Bradford.
GOCE view of the US and Mexico. Credits: ESA/HPF/DLR, anaglyph by Nathanial Burton-Bradford.GOCE view of Europe. Credits: ESA/HPF/DLR, anaglyph by Nathanial Burton-Bradford.GOCE view of Africa.. Credits: ESA/HPF/DLR, anaglyph by Nathanial Burton-Bradford.GOCE global view, 145 East Longitude. Credits: ESA/HPF/DLR, anaglyph by Nathanial Burton-Bradford.GOCE global view, 140 West Longitude. Credits: ESA/HPF/DLR, anaglyph by Nathanial Burton-Bradford.
This set of images by the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite shows March 19, 2010 on the left, and the right shows the same date in 2011. March 2010 had relatively high ozone, while March 2011 has low levels. NASA image by Rob Simmon, with data courtesy of Ozone Hole Watch.
In the past, massive ozone loss over Antarctica has grabbed the headlines. But this year, measurements by several different sources show record levels of stratospheric ozone loss over the Arctic. Scientists say the main reason for the record ozone loss this year is that unusually cold stratospheric temperatures, which have endured later into the season than usual. Scientists say the unusual loss is not catastrophic, but something that needs to be monitored.
The World Meteorological Organization cautioned that people who live in northerly latitudes could get sunburned easier, noting that ozone-depleted air masses extended from the north pole to southern Scandinavia.
The record low temperatures were caused by unusually strong winds, known as the polar vortex, which isolated the atmospheric mass over the North Pole and prevented it from mixing with air in the mid-latitudes.
This has allowed for the formation of polar stratospheric clouds, and the catalytic chemical destruction of ozone molecules occurs on the surface of these clouds which form at 18-25 kilometers height when temperatures drop below -78 C.
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This created conditions similar to those that occur every southern hemisphere winter over the Antarctic.
Measurements by ESA’s Envisat satellite, the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite, and France’s MetOp satellite, as well as observations made since January from the ground and from balloons show all show that 40% of ozone molecules have been destroyed over the Arctic.
Ozone is a protective atmospheric layer found at around 25 km altitude that acts as a sunlight filter shielding life on Earth from harmful ultraviolet rays, which can increase the risk of skin cancer and cataracts in humans and harm marine life.
Stratospheric temperatures in the Arctic usually do vary widely from winter to winter. Last year, temperatures and ozone above the Arctic were very high. The last unusually low stratospheric temperatures over the North Pole were recorded in 1997.
“This depletion is not necessarily a big surprise,” said Paul Newman, an atmospheric scientist and ozone expert at NASA’s Goddard Space Flight Center. “The ozone layer remains vulnerable to large depletions because total stratospheric chlorine levels are still high, in spite of the regulation of ozone-depleting substances by the Montreal Protocol. Chlorine levels are declining slowly because ozone-depleting substances have extremely long lifetimes.”
Ozone “holes” do not form consistently over the North Pole like they do in Antarctica. “Last winter, we had very high lower stratospheric temperatures and ozone levels were very high; this year is just the opposite,” Newman said. “The real question is: Why is this year so dynamically quiet and cold in the stratosphere? That’s a big question with no good answer.”
Scientists will be watching in coming months for possible increases in the intensity of ultraviolet radiation (UV) in the Arctic and mid-latitudes, since ozone is Earth’s natural sunscreen. “We need to wait and see if this will actually happen,” Newman said. “It’s something to look at but it is not catastrophic.”
Scientists are also investigating why the 2011 and 1997 Arctic winters were so cold and whether these random events are statistically linked to global climate change. “In a changing climate, it is expected that on average stratospheric temperatures cool, which means more chemical ozone depletion will occur,” said Mark Weber from the University of Bremen.
Experts say that on a global scale, the ozone layer is still on a long-term course for recovery. But for decades to come, there remains a risk of major ozone losses on yearly or regional scales.
