Last month I was in Portland, Oregon to give my Death from the Skies! talk for the Oregon Museum of Science and Industry as part of their Science Pub series. It was, quite seriously, one of the best audiences ever. They were totally into it – having beer served at the theater probably helped – and almost everyone stayed for the 45 minute Q&A session, and the line to sign books was pretty long as well. I felt like a rock star.
One person in the audience was Taylor Hatmaker, who writes for tecca.com. She wrote a wonderful article about the talk called 9 Terrifying But Mostly Awesome Facts About Asteroids We learned from Bad Astronomy’s Phil Plait (which was also picked up on Mashable! W00t!), and it makes my cockles warm because she added more info about the facts that weren’t in my talk. That means she liked this enough to go out and do more research, which is the coolest thing ever. That’s pretty much the best thing a speechifier and science outreacher can ask for.
To give you an idea of how much fun I had, photographer D. Scott Frey took a ton of pictures, including this one which is now one of my favorites:
See? I told you I had a great time! And clearly the end of the world can be fun.
My thanks to Amanda Thomas, Andrea Middleton, and Scott Frey for all their help and hospitality. If you ever get a chance to visit OMSI, do so!
<shameless plug> And if you represent a museum, University, or some other place that hosts talks, and you think I might be a good fit for your audience, then please contact my reps, Samara Lectures. They’ll be happy to chat with you about it. </shameless plug>
My friend Cara Santa Maria is a scientific researcher and educator. She’s also Senior Science Editor with The Huffington Post, where she does a video show called "Talk Nerdy To Me". She contacted me recently because she wanted to do an episode on solar storms – how they work, and how they can affect us here on Earth. She interviewed me about them, and the episode is online at HuffPo:
[Note: If the video doesn’t appear directly above this sentence, refresh your screen.]
The Sun has been a bit feisty lately, spitting out some decent flares and coronal mass ejections. So far, none has been both strong enough and aimed at us to do any damage (there was a fairly powerful CME in July, but it was on the other side of the Sun, directed away from us). And while they can’t hurt us directly due to our protective atmosphere, as I say in the video solar storms can disrupt our power grid and our satellites, creating havoc. The more we study the Sun the better we understand it, and the more likely we’ll be able to protect ourselves should it decide to throw another major hissy fit.
I’ll add that Cara’s good people, and I like her show (she interviewed me for the Venus Transit, too). She’s passionate about science education, and like me she finds real joy and wonder in all fields of science and nature. You can follow her on Twitter.
[Edited to add: the shirt I’m wearing in the video (watch to the very end!) is available at Lardfork’s Spreadshirt store.]
Because the planets are so terribly old, and impacts so rare, I still have this (very slight) prejudice that craters are old too. The Moon was bombarded billions of years ago, and the craters on Earth are mostly so old that they’ve eroded away. Heck, even a "new" crater like the one in Arizona is tens of thousands of years old.
Getting the age of a crater can be tricky. But sometimes it’s so easy it’s literally a matter of keeping your eyes on one spot. Like this spot on Mars:
That image (highly color enhanced; click here for a grayscale version) shows a crater seen by a camera on the Mars Reconnaissance Orbiter in 2011. We can tell it’s young because it’s still surrounded by the ejecta blanket; material that blasted out of the crater and settled around it. That stuff tends to erode away (or get covered in dust and sand by Martian winds) relatively quickly.
But in this case, we know just how young it is: it wasn’t seen in images taken of the same spot by a camera on board the Odyssey Mars probe… in 2009! In other words, this crater is less than three years old!
That’s so cool. And it speaks to the power of having multiple, sustained missions to other worlds. Things change. If we take one picture and then walk away, we’ll miss a lot.
Image credit: NASA/JPL/University of Arizona
As a reminder, I’ll be at the Bagdad Theater in Portland, Oregon at 7:00 tonight to give my "Death from the Skies!", which if I can be objective for a moment is the single greatest public speaking event you could ever even dream to hope to attend. And that’s me being objective.
Image credit: Wikimedia commons
I’m very excited to be heading up to Portland, Oregon on Wednesday, August 1, to give my "Death from the Skies!" talk at the Bagdad Theater. This is part of the OMSI Science Pub series, a laid-back event where people like me talk to people like you about stuff like science. In my case, I’ll be talking asteroid impacts and crispy dinosaurs and making fun of the movie "Armageddon" and then saving the world.
I’ll be doing a book signing afterwards, too. I’ve never been to Portland, so I’m pretty happy about this. I like Oregon quite a bit.
On July 9, 1962 — 50 years ago today — the United States detonated a nuclear weapon high above the Pacific Ocean. Designated Starfish Prime, it was part of a dangerous series of high-altitude nuclear bomb tests at the height of the Cold War. Its immediate effects were felt for thousands of kilometers, but it would also have a far-reaching aftermath that still touches us today.
In 1958, the Soviet Union called for a ban on atmospheric tests of nuclear weapons, and went so far as to unilaterally stop such testing. Under external political pressure, the US acquiesced. However, in late 1961 political pressures internal to the USSR forced Khrushchev to break the moratorium, and the Soviets began testing once again. So, again under pressure, the US responded with tests of their own.
It was a scary time to live in.
The US, worried that a Soviet nuclear bomb detonated in space could damage or destroy US intercontinental missiles, set up a series of high-altitude weapons tests called Project Fishbowl (itself part of the larger Operation Dominic) to find out for themselves what happens when nuclear weapons are detonated in space. High-altitude tests had been done before, but they were hastily set up and the results inconclusive. Fishbowl was created to take a more rigorous scientific approach.
Boom! Goes the dynamite
On July 9, 1962, the US launched a Thor missile from Johnston island, an atoll about 1500 kilometers (900 miles) southwest of Hawaii. The missile arced up to a height of over 1100 km (660 miles), then came back down. At the preprogrammed height of 400 km (240 miles), just seconds after 09:00 UTC, the 1.4 megaton nuclear warhead detonated.
And all hell broke loose.
1.4 megatons is the equivalent of 1.4 million tons of TNT exploding. However, nuclear weapons are fundamentally different from simple chemical explosives. TNT releases its energy in the form of heat and light. Nukes also generate heat and light, plus vast amounts of X-rays and gamma rays – high-energy forms of light – as well as subatomic particles like electrons and heavy ions.
When Starfish prime exploded, the effects were devastating. Here’s a video showing actual footage from the test, 50 years ago today:
As you can see, the explosion was roughly spherical; the shock wave expanding in all directions roughly equally since there is essentially no atmosphere at that height. Another video has many more views of the test; I’ve linked it directly to those sequences, but if you start at the beginning it’s actually an hour-long documentary on the test.
Nuke ’em ’til they glow
[Note: In the interest of full disclosure, I am friends with many of the folks on both teams described below. I have tried to be scrupulously fair to both missions, and to be honest – as I say below – the best thing to happen would be for both missions to be locked, loaded, and looking for potentially hazardous rocks.]
The B612 Foundation is a group of scientists, astronauts, astronomers, and engineers who have come together to do nothing less than literally save the world: they want to find and deflect asteroids that can potentially hit the Earth. While really big asteroids are rare — after all, the one 10 km (6 miles) across that wiped out the dinosaurs only hits Earth every few hundred million years — smaller ones in the 100 meter range are far more common and can still do devastating damage. Even one just 50 meters across (smaller than a football field) can impact and explode with the yield of millions of tons of TNT. That’s in the range of the biggest nuclear weapons ever detonated.
Finding these asteroids is notoriously difficult. They’re small and dim, and sometimes only discovered once they’ve already passed us! The best way to find them in large numbers is to launch a space telescope to survey the sky, tuned to the infrared where these asteroids are far brighter and easier to spot.
Today, B612 made a big announcement: they want to build just such a mission. They call it Sentinel, and it will be the first privately funded deep space mission ever launched. Built by Ball Aerospace and launched on a SpaceX Falcon 9 rocket, it will be placed into a Venus-like orbit, giving it a good view of the volume of space where these asteroids prowl:
[Click to chixchulubenate.]
The plan is to raise the money philanthropically, like museums do: donations from private funders. Observatories have long been funded this way, and the proposed cost of a few hundred million dollars is roughly on par with many civic projects. Their target launch date is 2017 to 2018, and the mission will last about 5 years.
Sentinel and NEOCam have many similarities: they both use a 50 cm or so telescope, both are tuned to infrared, and both will launch into orbit to get a better view of potentially threatening asteroids. Read More
On June 14, 2012, the asteroid 2012 LZ1 passed the Earth. It missed us by a wide margin, over 5 million kilometers (3 million miles), so there was no danger of impact. While it does get near us every now and again, using current orbital measurements we know we’re safe from an impact by this particular rock for at least 750 years. Phew.
Good thing, too. New observations using the Arecibo radio telescope in Puerto Rico indicate LZ1 is bigger than we first thought. Much bigger: it’s about a kilometer across, when it was thought to be half that size before these observations.
That’s a big difference. The problem is that the size of an asteroid is hard to determine. Even a big one may only appear as a dot in a telescope, so even though we may know its distance and trajectory very accurately, directly measuring its size isn’t possible. Usually, the size is estimated by knowing its distance and how bright it appears. In general, a bigger rock will look brighter than a smaller one at a given distance.
But that assumes they both reflect the same amount of light. Most asteroids reflect about 4% of the sunlight they receive (this property is called the albedo), but that depends on their surface. Some have darker surfaces, some brighter. If you don’t know how reflective it is, the size can only be estimated.
But the Arecibo telescope can actually directly measure the size of a nearby asteroid. It can send pulses of radio waves at an asteroid and then receive the reflected waves, much like a cop on the side of the road uses radar to measure a car’s speed. The method is technical (Emily Lakdawalla has a great explanation on her blog), but it was used for LZ1 to get the new size measurement. The picture above is the actual image generated using Arecibo when the rock was still 10 million km (6 million miles) from Earth. Apparently, LZ1 is much less reflective than assumed earlier, which is why the size was underestimated by a factor of two.
An asteroid this size hitting the Earth would be, um, bad. That’s big enough to be considered a global hazard, causing immense devastation. It might not be an extinction event — the dinosaur-killing asteroid was 10 km across, so it had 1000 times the mass of LZ1 — but it wouldn’t be fun. So I’m glad we’re safe from this guy for some time!
But I’ll be honest: LZ1 was only discovered a few weeks before it passed us. Asteroids this size passing near us are pretty rare (we haven’t had an impact from something this big for many, many millennia) so as usual I’m not panicking about this. But it just shows once again that we need more eyes on the sky, more people looking. And we need a plan in place in case we do see one with our name on it.
– Asteroid 2011 AG5: a football-stadium-sized rock to watch carefully
– My asteroid impact talk is now on TED
– Another tiny rock will pass Earth tomorrow
– Updated movie of asteroid YU55, plus bonus SCIENCE
– Just to be clear: asteroid YU55 is no danger to Earth
– Armageddon delayed by at least a century… this time
On April 22, 2012, a chunk of asteroid one or two meters across burned up in Earth’s atmosphere. It came in over California and was seen by a lot of people, despite it occurring at about 8:00 a.m. local time and in broad daylight.
I just became aware that some footage was taken of the event, and as far as I know is the only video we have of it. It was taken by Shon Bollock, who was making a time-lapse kayaking video just outside Kernville, California as part of his Shasta Boyz adventuring website:
Pretty cool! It looks like he caught the very beginning of it burning up in the upper atmosphere. Not long after this, the meteoroid broke apart, raining down small meteorites onto the ground which were later found spread over the countryside.
The video is being studied by astronomers and meteoriticists to try to calculate the trajectory, speed, and possible orbit of the object. This is difficult with just one video, so if you have pictures you took or, better yet, more video, please let me know!
Tip o’ the Whipple Shield to Aaron Johnson on Twitter.
[tl;dr: A small 5-10 meter asteroid will pass us tomorrow; it poses no danger to us.]
[UPDATE (May 29, 16:30 UTC): The JPL website for this asteroid has been updated – the rock passed us at the predicted distance of about 14,500 km from the Earth’s surface. The new numbers use 50 observations of the asteroid (the earlier orbit calculations used far fewer), so this looks pretty solid to me. As we knew all along, it was a close pass, but nothing to worry about.]
I recently wrote about near-Earth asteroid 2012 KP24, a house-sized (25 meter) rock. As I write this it passed us safely just a few hours ago, as predicted.
But thanks to scibuff and AsteroidWatch on Twitter, I just learned of another tiny visitor that will buzz past us tonight/tomorrow, May 29, at around 07:00 UTC (03:00 Eastern US time). Called 2012 KT42, this one is even smaller than KP24: it’s probably less than 10 meters across — about the size of a school bus or more likely a minivan. And it’ll be a close shave: though the orbit is still not nailed down, the nominal miss distance is about 14,500 kilometers (8900 miles). That’s a bit bigger than the diameter of the Earth itself.
I’ll add more here if I hear anything.]
[UPDATE (19:55 UTC): No new info as such, but Alex Gibbs from the Catalina Sky Survey sent me this nice 4-tile mosaic of the discovery images of KT42, taken with the Mt. Lemmon 60" telescope:
Bear in mind, it was only discovered last night, so the current orbit is preliminary. Many small rocks that pass close to Earth are discovered shortly before they breeze past us (and some not until after), so this is nothing out-of-the ordinary.
And since some people tend to get upset about these things, I’ll point out that as of right now, it looks like it will miss us. And even if newer observations show it hitting us, this rock is way too small to do any damage. At that size, it’ll break up in the atmosphere and make a spectacular light show, but not much else. This has happened countless times with asteroids this size, like the Peekskill meteor in 1992, or the more recent fireball over California last April. These can produce meteorites which fall to Earth, but the odds of getting by one are so small they’re basically zero.
Put it this way: the Earth has a surface area of more than 500 trillion square meters. Your surface area is less than 1 square meter (as seen from above). Those are pretty good odds you’ll be OK.
Another way to think about this is that rocks this size pass us all the time, but you never hear about them hurting us; that’s because they don’t! The smaller the asteroid the more common they are, but the less they can do to us. At this size, there’s no danger.
And as usual, I’ll point out that this discovery is a good thing! It shows we can find them, and that’s important. If we ever do discover an asteroid on a collision course that’s big enough to hurt us, the first step is to find it. And we’re getting better at that all the time.
– Small asteroid to buss Earth on May 28
– A brief bit about asteroid 2012 DA14
– No, asteroid 2012 DA14 will not hit us next year
– Asteroid 2011 AG5: a football-stadium-sized rock to watch carefully
– Updated movie of asteroid YU55, plus bonus SCIENCE
– Asteroid 2007 TU24: No Danger to Earth