Archive for September, 2012

Time lapse: All Is Violent, All Is Bright

By Phil Plait | September 30, 2012 7:09 am

For this, the last day of the US Fiscal Year, here’s a lovely time lapse video from Tadas Janušonis, a photographer in Lithuania. It’s called "All is Violent, All is Bright", and features a series of interesting optical phenomena in the sky.

Did you catch everything? There were noctilucent clouds, halos, moondogs, and a brief lunar corona.

But my favorite is the phenomenal oncoming storm starting three minutes in.

That, or the giant spider (at 2:40) clearly bent on destroying the world. I’m partial to stuff like that.

CATEGORIZED UNDER: Astronomy, Cool stuff

SpaceFest IV interview

By Phil Plait | September 29, 2012 7:00 am

In May I attended SpaceFest IV, a gathering of space enthusiasts, astronauts (who, I suppose, are legit space enthusiasts), astronomers, and more. It’s a lot of fun, and great to see old friends and meet new science geeks. I missed last year’s, unfortunately, but was happy to be able to go this year again.

While I was there I was interviewed about the Mayan apocalypse, Symphony of Science, and building a real Enterprise. It was an eclectic series of questions.

There are also video interviews of my friends Dan Durda and Meteorite Man Geoff Notkin, too.

I hope there’ll be another SpaceFest next year! I had a lot of fun, and I bet a lot of you reading this would too.

Related Posts:

- Come to Space Fest IV!
- A Spacefest Odyssey
- Spacefest 2009
- Spacefest wrapup

Interview with NASA's Blueshift podcast

By Phil Plait | September 28, 2012 10:56 am

My friend Sara Mitchell works at NASA’s Goddard Space Flight Center doing education and public outreach for the space agency. She and her partner, Maggie Masetti, interviewed me a while back for their podcast Blueshift, and the first part is now online.

We talked a bit about my history as a skeptic, and why we all need to keep asking, "Why?" There are three more segments to the interview that will go up in the next few weeks, so stay tuned to the Blueshift website and collect ‘em all!


The August solar eruption, in HD video!

By Phil Plait | September 28, 2012 6:56 am

In August, the Sun erupted in an epic explosion: a towering arc of material blasted off the surface and into space. The images of it were incredible enough, but the folks at NASA/Goddard Space Flight Center put together an astonishing high-def video of the eruption as seen by the Solar Dynamics Observatory, the Solar Terrestrial Relations Observatory (or STEREO), and the Solar Heliospheric Observatory (SOHO):

Yowza. Set it to hi-res and make it full screen. Try not to drool.

They have more images, videos, and higher-resolution stuff on the GSFC Multimedia site. You really want to go there and take a look.

Our Sun is gorgeous, and dangerous, and amazing. These pictures and videos are more than just beautiful; they are telling us about the mechanisms and processes occurring both on the surface and inside our nearest star. Given the impact this can have on Earth, the more we know, the better.

Related Posts:

- A HUGE solar filament erupts into space
- Talk Nerdy To Me: Solar Storms
- The Sun blasts out a flare and a huge filament
- GORGEOUS solar eruption!

CATEGORIZED UNDER: Astronomy, Pretty pictures

The life of a star, in 14 minutes

By Phil Plait | September 27, 2012 10:55 am

A popular style of do-it-yourself video is what I think of as the "stop-motion whiteboard drawing", where someone films someone else drawing on a whiteboard, explaining some concept or another. It’s surprisingly engaging, and a lot of otherwise complex topics can be better understood this way.

Case in point: how do stars work? How are they born, live out their lives, and die? The overall story isn’t conceptually difficult, but there are some important details (like how massive the star is) and it can be easy to lose the thread. But if you watch this video, Life of a Star, your understanding will be a whole lot better:

This gives you a pretty good overview of how things work, and I’d certainly recommend it for any Astronomy 101 students who want a quick review, or sciencey-type folks who just enjoy learning about the Universe. Which, admit it, is you. There’s just enough info there to make sense of stellar life cycles, and if you want details, well, there’s Google. Or my book. Either way, if you want more fun stuff about star formation, evolution, and eventual demise, you can find it – and this video is a great start.

Tip o’ the hydrogen burning shell to Tony Silva via a chain of links starting at Giovanni Picogna.

Related Posts:

- More M95 supernova news: progenitor found!
- Betelgeuse’s sandy gift
- Does this cluster make my mass look fat?
- The evolution of creationist astronomy (which is a followup to this)

CATEGORIZED UNDER: Astronomy, Cool stuff

A penetrating, double-ringed crater on Mars

By Phil Plait | September 27, 2012 6:55 am

Mars is weird. Right? I mean, it’s a whole other planet. So you expect it to be weird.

But then I see pictures like this one from the Mars Reconnaissance Orbiter’s HiRISE camera, and I am reminded just how weird it is:

[Click to chicxulubenate.]

Most craters you see are pretty simple: something impacts the ground at high speed, BOOM!, and you get a crater like a dish tossed into soft sand. But this one has two rings, one inside the other. That can happen with huge impacts producing craters hundreds of kilometers across, but this one is small, only 230 meters from side to side – an American football stadium would just fit inside this crater.

The most likely explanation for the double ring is that the Martian landscape here is layered. There’s rock and sand on the surface, but underneath that is a layer of ice. The big rim is from the displaced rock, and the inner, smaller ring is from the impactor plowing through the ice. Each layer has a different strength – rock is harder than ice – so it’s as if two craters were formed, one inside the other. Radar observations of Mars from orbit have indicated there’s ice under the surface in this region, so that fits.

Similar double-ringed craters have been seen on Mars – though the structure and history is by no means well understood! – and some have been found on the Earth’s Moon as well. Those tend to be big, as I mentioned, though they don’t have to be.

By the way, the image above is color enhanced to show details. The blue may be from carbon dioxide frost, which can be seen in similar color-enhanced HiRISE images. The ripples in the center are sand dunes, sculpted into parallel waves by the ceaseless Martian wind.

Craters this small on Earth are extremely unlikely to form; the impactor would be maybe 20 meters or so across, and objects that size tend to break up when they ram through our thick atmosphere at high speed. Mars has much thinner air, so rocks that size can hit intact. Studying craters on Mars is a chance to see what these hypervelocity impacts are like under very different conditions, which helps us understand them. The physics of extremely high-speed collisions is hard to study experimentally – accelerating large objects to that kind of speed is both difficult and more than slightly dangerous – so it’s nice to have a lab like Mars where we can observe these effects.

Tip o’ the lens cap to HiRISE on Twitter. Image credit: NASA/JPL/University of Arizona.

Related Posts:

- Mars craters are sublime
- Desktop Project Part 1: A weird Moon crater
- The artwork of the Martian landscape
- A fresh Martian impact

CATEGORIZED UNDER: Cool stuff, Pretty pictures

Two talks in the Old Dominion!

By Phil Plait | September 26, 2012 12:30 pm

This week sees me returning to the state I grew up in: Virginia.

I’ll be at James Madison University Thursday, September 27 to give my "2012: We’re All (not) Gonna Die!" talk – basically destroying the Mayan December 21, 2012 apocalypse nonsense – at 7:00 p.m at the Wilson Hall Auditorium. Admission is free and open to the public.

The talk is sponsored by the John C. Wells Planetarium, JMU Department of Physics & Astronomy, College of Science & Mathematics, and the JMU Center for STEM Education & Outreach. They even made the awesome poster seen here! [Click to Kukulkanenate.]

Then, the next day – Friday, September 28 – I’ll be at my alma mater, the University of Virginia, to be the keynote speaker for the 2012 Forum for Interdisciplinary Dialogue called "Fact, Fiction, and Supposition"! I’m honored to be a part of this event sponsored by the Jefferson Scholars Foundation and the Jefferson Graduate Fellows at the University of Virginia.

That talk is also open to the public, and will be at 16:00 at The Jefferson Scholars Foundation Hall. They’ve set up a Facebook page for the event if you like that sort of thing. My good friend Dr. Nicole Gugliucci (and UVa alumna) will be speaking the next day there, too!

I haven’t been back to central Virginia in a good long time, so it’ll be nice to see it again. I hope the trees are turning now! And I hope to see some of you Wahoos there, too.

Related Posts:

- If the Mayans were right, it was probably about Internet comments
- Re-cycled Mayan calendar nonsense
- MSNBC interview: 2012, the year the Earth doesn’t end. Again.

Water bomb

By Phil Plait | September 26, 2012 10:30 am

Via Jenny Winder, I saw this video showing footage from underwater nuclear bomb tests in 1958. It’s astonishing.

The awesome power and energy released is difficult to wrap your head around. Think on this: a cubic meter of water weighs a ton. Now imagine taking a single cubic meter of water and lifting it, say, 100 meters in the air, accelerating it to several hundred kilometers per hour.

Now look again at that plume. How many cubic meters of water were are in it? Even being conservative I’d say it was in the millions, meaning millions of tons of water blasted upward and outward by the force of the explosion. It’s terrifying. And mind you, the test shown was for a relatively small blast: about an 8 or 9 kiloton yield (the equivalent of 8-9 thousand tons of TNT), whereas big nukes are capable of 20 megatons, over a thousand times the explosive yield shown.

I’m fascinated by big bangs – from the first one, to supernovae, and all the way down to bombs we humans make in our clever and plodding attempts to kill one another. Every now and again it’s good to get a solid reminder of just what these explosions are capable of.

Related Posts:

- The 50th anniversary of Starfish Prime: the nuke that shook the world
- What the hell were we thinking?
- Starfish Prime
- Would you stand under a nuclear blast?

CATEGORIZED UNDER: Piece of mind, Science

UPDATE on the big UK fireball

By Phil Plait | September 26, 2012 7:00 am

There’s been a bit more news on that amazingly bright and weird fireball seen moving across the skies of northern UK last week.

Marco Langbroek is a paleolithic archaeologist in Amsterdam, and also an amateur satellite tracker – though with modern tech, the term "amateur" is arguable. Anyway, he’s been looking at the track and velocity of the meteor using eyewitness accounts (and the video taken), and thinks he can rule out the cause being the re-entry of human-made debris from a spacecraft. In fact, he thinks the meteoroid (the term for the actual object responsible for the light show) was an Aten asteroid: part of a class of rocks that orbit the Sun on paths that tend to keep them inside Earth’s orbit*.

The key issues here are the slow speed it moved across the sky, and the fact it moved east-to-west. That last part is really important: very few satellites orbit retrograde, or in that direction. Most orbit either prograde – west-to-east, the same direction the Earth spins and also the same direction it orbits the Sun – or in polar orbits (north/south). So right away that makes it unlikely the meteor was from a spacecraft.

However, what has me scratching my head is the slow speed of the meteor. A rock orbiting the Sun retrograde means its velocity will add to the Earth’s, making it move faster as it burns up, not slower. It’s like two cars in a head-on collision; if each is moving 100 km/hr then the resulting collision speed is 200 km/hr relative to either car. You get slower relative collisions if they’re moving in the same direction; they’ll merely bump at low speed relative to one another.

We see this with meteors; the Leonid meteor shower, for example, is made up of tiny particles that move almost in the opposite direction of the Earth, and when they burn up in our atmosphere they move extremely rapidly across the sky. The collision speeds can be 70 kilometers per second!

So why was this meteor over the UK moving so slowly if it were an Aten? Marco thinks he has the answer to that. If the asteroid happened to be at aphelion – the top of its orbit, when it’s farthest from the Sun, also when moving most slowly and in a direction nearly parallel with that of the Earth – it would all add up. The backwards direction and the slow motion would be a natural consequence of this. [UPDATE: I made an error here: the asteroid can orbit the Sun prograde! When it's at the top of its orbit, it can be moving slower than Earth does around the Sun, so when we look at it it appears to move east-to-west. It's like passing a slower car in a faster one; to the driver of the passing car, the slower one appears to be moving backwards when in reality they are both moving in the same direction. I hope that clears up any misunderstanding!]

I’ll note that as far as I have thought about this, I agree with Marco. It’s not conclusive yet, though, but it’s compelling.

Meteors like this are rare. One that gets this bright, is seen by so many people, and drops bits of itself as it burns up are rare enough (the Peekskill meteor in 1992 is the best example of this), but one moving retrograde is even weirder. If Marco is right then I hope even more people submit their observations, pictures, and videos to the International Meteor Organization website. Those observations can help scientists determine the orbit of the object more accurately, and help pin down exactly what the heck this crazy object was.

Image credit: Craig Anderson

* Technically, an Aten asteroid has a semi-major axis less than one Astronomical Unit. Orbits are elliptical, and the semi-major axis is the half-diameter of the orbit along the long axis. Despite this, an Aten can cross the Earth’s orbit if its orbit is elongated (eccentric) enough.

Related Posts:

- VERY bright and spectacular meteor seen over northern UK!
- Video of the daylight California fireball
- Best video of Soyuz rocket burning up so far
- A meteor’s lingering tale

CATEGORIZED UNDER: Astronomy, Cool stuff

Revealing the Universe: the Hubble Extreme Deep Field

By Phil Plait | September 25, 2012 12:13 pm

Astronomers using the Hubble Space Telescope have created the deepest multi-color* image of the Universe ever taken: the Hubble Extreme Deep Field, a mind-blowing glimpse into the vast stretches of our cosmos.

Check. This. Out.

Yegads. [Click to cosmosenate, or grab the bigger 2400 x 2100 pixel version.]

This image is the combined total of over 2000 separate images, and the total exposure is a whopping two million seconds, or 23 days! It’s based on the original Hubble Ultra Deep Field, with new observations added in since the originals were done. It shows over 5500 galaxies – nearly everything you see in the picture is a galaxy, an island universe of billions of stars. Only a handful of individual stars in the foreground of our own galaxy can be seen.

Here’s some detail from the image:

The variety of galaxies is amazing. Some look like relatively normal spirals and ellipticals, but you can see some that are clearly distorted due to interactions – collisions on a galactic scale! – and others that look like galaxy fragments. These may very well be baby galaxies caught in the act of forming, growing. The most distant objects here are over 13 billion light years away, and we see them when they were only 500 million years old.

In case your head is not asplodey from all this, I’ll note that the faintest objects in this picture are at 31st magnitude: the faintest star you can see with your naked eye is ten billion times brighter.

So, yeah.

I’ll note that the purpose of this and the other deep field images is to look as far away and as far back in time as we can to see what the Universe was like when it was young. The wealth of data and scientific knowledge here cannot be overstated.

But I suspect, in the long run, the importance of this and the other pictures will be their impact on the public consciousness. We humans, our planet, our Sun, our galaxy, are so small as to be impossible to describe on this sort of scale, and that’s a good perspective to have.

But never forget: we figured this out. Our curiosity led us to build bigger and better telescopes, to design computers and mathematics to analyze the images from those devices, and to better understand the Universe we live in.

And it all started with simply looking up. Always look up, every chance you get. There’s a whole Universe out there waiting to be explored.

The folks at Hubble will be holding a public interactive discussion of the HXDF image on Google+ at 13:00 Eastern (US) time on September 27th, where you can ask astronomers questions. Tune in and learn more!

Image credit: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team

* In 1998 a single-color image was taken with the STIS camera on Hubble, and reached similar depth. It would take some serious analysis to know which image sees fainter objects!

Related Posts:

- Astronomers have found when and how the cosmic fog was lifted (a brief history of the young Universe)
- Another record breaker: ultra-deep image reveals ultra-distant galaxy
- Record-breaking galaxy found at the edge of the Universe
- Hubble digs deep to see baby galaxies

CATEGORIZED UNDER: Astronomy, Pretty pictures

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