In one way or another, by now you’ve probably heard today’s news:
Nelson Mandela, South Africa’s Liberator as Prisoner and President, Dies at 95
That’s how the New York Times elegantly summed it up in its headline on Mandela’s obituary.
In coming days I’m sure we’ll be hearing a lot about the man who did indeed go from prisoner to his nation’s first black president, on the way engineering a peaceful transition from apartheid to free elections — and “becoming an international emblem of dignity and forbearance,” as Bill Keller put it in his obituary.
I thought I would contribute in a very small way to honoring the memory of Mandela by sharing a photo Tweeted by NASA today — the image of South Africa at the top of the post. It was taken in May by Commander Chris Hadfield when he was still aboard the International Space Station.
May Mr. Mandela rest in peace.
I’ve explored the Grand Canyon’s inner recesses on hiking and backpacking trips at least a half dozen times. I’ve seen it under a hot summer sun and with a blanket of snow. But even after all of those experiences, I never would have guessed that this photograph was taken there.
It was, in fact, the sunrise view from Mather Point at the South Rim as fog filled the canyon on November 29. The photograph was taken by Paul Lettieri, who kindly allowed me to share it here.
You may have already heard about this once-in-a-decade event, which received quite a bit of coverage starting the day after Thanksgiving. But you probably have not seen some of the following imagery that I’ve put together, including an amazing time lapse video, once again courtesy of Paul Lettieri, and also some remote sensing views. So keep reading… Read More
Imagine four atomic bombs like the one that incinerated Hiroshima, Japan on Aug. 6, 1945 exploding in the atmosphere every single second of every day of every week and every month, year after year, ad infinitum.
That, says John Cook and colleagues at the web site Skeptical Science, is a good way to understand the excess heat that is building up in the atmosphere as a result of humankind’s emissions of carbon dioxide and other greenhouse gases.
Four atomic bombs’ worth of extra energy, every second.
My friend and fellow Discover blogger Keith Kloor called this, well, explosive comparison “The Climate Bomb.” Thus my headline, “The Climate Bomb Redux.”
I found it compelling at first. But despite my respect for Skeptical Science — a site I have used many times — I soon found myself taken aback by the comparison. I also began to wonder whether it really would help improve climate change communication, and also about the scientific context.
So I decided to investigate. This post is the result of what I’ve come up with. Read More
The massive winter storm that swept across much of the United States right before Thanksgiving left behind quite a lot of snow in places. From space, the blanketing of snow brings out aspects of the landscape that otherwise are difficult to discern, including the spectacular New River in West Virginia, visible in the animation above.
The series of three images charts the turning of the seasons in this part of the country, from the leafing out of forests in May, to the rusty colors of fall foliage, and lastly the arrival of snow last week.
The New River is most clearly evident in the snowy scene. Look for the deeply incised river valley running north in the middle of the scene from the folded ridges of the Appalachian Mountains at the bottom of the image, and turning northwestward in the upper left quadrant.
In a post yesterday, I declared Comet ISON dead after it appeared to have gone dark during its closest approach to the sun. And I had good reason. Scientists observing the event had proclaimed it so.
But as the animation of images from the STEREO-B spacecraft above shows, something sure is glowing brightly as it speeds away from the sun now. Has it risen from the dead? If it has, is it now just a shadow of its former self — perhaps a clump of fragments traveling together but something we shouldn’t call a bona fide “comet” anymore?
Or as Karl Battams, an astrophysicist with the Comet ISON Observing Campaign put it in a headline on one of his fabulous blog posts, maybe it is “Schrödinger’s Comet,” meaning it is alive and dead at the same time, at least for now? For an explanation of exactly what this means, make sure to keep reading to the end…
|Update 10:30 a.m. 11/29/13: As I noted in my first update immediately below, Comet ISON seems to be showing new signs of life. I’m now working on a new post about that. I should be able to publish it by the end of the day, so please check back. In the meantime, a mea culpa: On its closest approach to the sun, ISON really did not seem to have a pulse — but I should have waited before declaring it dead. Although scientists were indeed speaking as if it had met its demise, I should have waited for a more definitive assessment.
There is also one other intriguing possibility: Comet ISON may be alive and dead at the same time. For an explanation of that, please come back later today. In the meantime, I’ve changed the headline on this story. (It had read “Death of Comet ISON Captured by NASA’s STEREO Spacecraft.”) |
|Update 9:30 p.m. 11/28/13: My headline might have been premature! After scientists were declaring ISON dead there’s some fleeting evidence that maybe, just possibly, a small, intact chunk of ISON’S nucleus survived. Read about it in Karl Battam’s “Schrödinger’s Comet” (!!) blog post at the Comet Ison Observing Campaign web site. (Maybe it really is dead and alive at the same time! |
This morning, hope was fading as fast as Comet ISON’s glow itself — and whatever sliver remained was dashed when it became clear that the traveller from at least 400 billion miles away had disintegrated on its close approach to the sun.
You can see it happen in the animation above, consisting of images from NASA’s STEREO-A spacecraft. When you watch it, don’t blink. ISON streaks toward the sun, circles around it, and emerges as not much more than a ghost of its former self.
The comet’s nucleus was probably no more than a mile across as it made its fateful approach, and the intense heat of the sun evidently melted all of the ice that had served as a kind of mortar to hold the more solid stuff together. As it whipped around the sun, ISON seems to have been reduced to a hurtling cloud of debris.
Here’s a stunningly beautiful image of ISON just as it appears to be blinking out: Read More
| Update 10 a.m. MST: I’ve added a spectacular video to the bottom of this post showing Comet ISON streaking toward the sun. It’s from NASA’s SOHO spacecraft. |
We’re just a few hours from Comet ISON’s closest approach to the sun, and the news is not encouraging: The sungrazer has gotten dramatically dimmer, according to Karl Battams of the Comet ISON Observing Campaign.
The two images above were captured by NASA’s SOHO spacecraft. The bottom image was acquired earlier, the top one later. And the dimming is evident. Based on what he’s seeing, Battams says he is not at all confident that ISON will survive intact after perihelion, meaning it’s closest approach to the sun, which should occur at 1:44 p.m. EST today:
The question on everyone’s lips is “will it survive perihelion?”, and now I’m reluctantly thinking it seems very unlikely to survive at this point. I do think it will reach perihelion, and reach the NASA SDO field of view, but based on what I see it doing right now, I will be very surprised to see something of any consequence come out the other side.
But Battams also points out that the comet has “done completely the opposite of what we expect, and it certainly wouldn’t be out of character for this dynamic object to again do something remarkable.”
NASA’s SDO spacecraft should be picking up views of ISON very soon. So we should get a new look at what’s happening. As soon as images come in, I’ll post them.
Update: Here’s new video from the SOHO spacecraft of the comet approaching the sun:
The sun is in the central circle. It’s blacked out so its glare does not overpower everything else in the image, including massive ejections of material that are evident as the comet approaches. These are called coronal mass ejections, or CMEs, and there appear to be at least two of them. Watch carefully as the comet dives in — it does indeed appear to be dimming considerably.
Snow blankets the higher terrain at the heart of the 130,000 square-mile Colorado Plateau in this image captured by NASA’s Terra satellite yesterday.
Left behind by the same storm system that’s now hammering the East Coast, the snow frames the deeply incised canyonlands of the Colorado River and its tributaries, which runs diagonally across the image. At lower left, where the river makes a big bend, you can spot the Grand Canyon. It bisects the Kaibab Plateau (part of the bigger Colorado Plateau), which reaches an elevation 9,241 feet above sea level. The darker, greenish coloring that edges the snow-covered area is indicative of forests that grow on this higher ground.
Also visible in the image is Lake Powell, the reservoir on the Colorado River that serves as a massive hydrologic savings bank for some 30 million people in seven states and Mexico who depend on water from the river and its tributaries. The snow is a good sign for a region plagued by drought for more than 10 years.
And with that let me wish everyone a very happy Thanksgiving!
|Update 1:15 p.m. MST, 11/27: Karl Battams of the Comet Ison Observing Campaign is reporting that the comet is brightening in line with other sungrazing comets. Writing in his latest update, Battams says, “We cannot comment on whether the nucleus is intact or not, but our analyses indicate that its rate of brightening is directly in line with that we have experienced with other sungrazing comets. This has no implication on its chances of survival.” So, will Comet Ison survive it’s passage through the sun’s million degree corona tomorrow? Stay tuned… |
Here comes Comet ISON, streaking toward the sun at more than a hundred thousand miles per hour — and now visible for the first time to NASA’s Solar and Heliospheric Observatory spacecraft.
No sooner had the comet entered SOHO’s field of view than the sun let loose with a massive eruption of particles called a coronal mass ejection, or CME. You can see it all in the image above, from SOHO.
In the image, the sun — indicated by the circle in the middle — is blacked out so dimmer features like the CME can be seen clearly.
Is ISON still intact? Yesterday, the evidence was suggesting that maybe it was not. But a definitive answer still isn’t at hand. As soon as there’s news, I’ll post it here. Stay tuned.
By now, you’ve probably heard of it: Winter Storm Boreas, the beast that threatens to disrupt travel for millions of Americans on the eve of Thanksgiving. But have you seen it in this light?
The image above is a false-color, composite view of the United States from NASA’s Terra satellite. It was captured yesterday by the MODIS instrument and emphasizes wavelengths of light that are particularly good at highlighting snow and ice. In the image, snow is revealed by the vivid red-orange colors. But what we’re interested in is the salmon coloring, which reveals the presence of small ice crystals in high-level clouds.
That big splotch of salmon coloring in the South and Midwest is what was headed for the East Coast yesterday. And now it has arrived, bringing a really nasty mix of snow, sleet, rain and wind. Here’s what it looks like as I’m writing this, in an animation from a GOES weather satellite: Read More