Tag: asteroid impact

Near-Earth asteroid twice as big as previously thought

By Phil Plait | June 22, 2012 11:00 am

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.

Related Posts:

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

MSNBC interview: 2012, the year the Earth doesn't end. Again.

By Phil Plait | March 14, 2012 7:00 am

I was at the SXSW tech conference over the weekend to be on a panel about 2012 doomsday nonsense. Right after, Helen Popkin of MSNBC interviewed me about this stuff:

[If the video above doesn’t load, hit refresh; I’ve found that happens sometimes and refreshing usually fixes it.]

The panel was fun — I gave an overview to and quickly debunked a bunch of 2012 claims, while JPL scientists Don Yeomans and Veronica McGregor talked about asteroid impacts, and what NASA is doing to calm unfounded fears about them. Asteroids are indeed a threat, but that danger is routinely exaggerated way beyond reality by lots of folks (YouTube fearmongers, I’m looking at you). There’s no real danger of the Earth ending in 2012, Mayan calendar-wise or otherwise — but the real danger is the overhyped fear of nonsense.

Forewarned is forearmed. Be aware of the reality of the situation, and save yourself a lot of trouble.

TED talk Q&A live online

By Phil Plait | November 28, 2011 10:51 am

On Friday, Thursday, December 1, at 1:00 p.m. Eastern (US) time (18:00 UTC) I’ll be doing a live online chat about asteroid impacts and astronomy at the TED website. This text-based chat is open to anyone; all you have to do is register which is free and only takes a moment.

The chat will revolve around my TED talk called "An Asteroid Impact Can Ruin Your Whole Day", which I gave here in Boulder in September. You can watch that talk online, which I suggest you do if you want to come to the chat. It’s only 14 minutes long, but it does feature me gesticulating a lot.

If you’re curious what it will be like, my Discover Magazine co-blogger Sean Carroll did a TED chat in May 2011. This is a fun way to interact with people, and I’m looking forward to it, so drop on by and ask a question!

CATEGORIZED UNDER: About this blog, Astronomy, Cool stuff

My asteroid impact talk is now on TED!

By Phil Plait | November 22, 2011 7:00 am

I am extremely honored and pleased to announce that my talk, "An asteroid impact can ruin your whole day", is now featured on the TED website!

I gave this talk in September at TEDxBoulder, and I had a fantastic time. The talks were great, and it was wonderful to be a part of that.

However, I made two errors in this talk. One was logistical; I forgot to say that the "dinosaur space program" line is from science fiction writer Larry Niven, and for that I apologize to him — I usually do credit him, so I’m not sure what happened there.

The second error?
Read More

Media FAIL *again* (HuffPo and Apophis edition)

By Phil Plait | February 9, 2011 5:20 pm

Oh for FSM’s sake. Again?

First, let me be clear: the odds of the 250-meter-wide asteroid Apophis hitting the Earth in 2036 are extremely slim, like less than 1 in 135,000 (and I just heard 1 in 250,000 from another expert). This is less than the odds of getting dealt a straight flush in five-card stud poker. Those are teeny tiny odds.

So then why oh why did The Huffington Post just put up an article about Apophis hitting us in 2036? With the headline "Apophis Asteroid Could Hit Earth In 2036, Scientists Say"? After I already posted that this original story was totally garbled by a Russian journalist, who grossly misquoted a Russian astronomer?


Now, they claim this info comes from a UPI article, but that article is pretty clear about the odds. While the HuffPo article also puts in the odds, they interlace it with a lot of doomsday stuff.

For example, they used a graphic illustration right at the top of a huge asteroid impact, just to make sure they scare their readers. They also include a video, saying "Watch a shocking visualization of what the event could look like,"… and the video shows what it would look like if the Earth were hit by an asteroid that was 800 km (500 miles) across.

That’s a little bit bigger than 250 meters. By a factor of 30 billion (in volume, which is what counts in impacts). I actually wrote about this video a couple of years ago. While an Apophis impact would suck (if it happened, which it almost certainly won’t), it would not rip the crust of the planet off and eject it into space, leaving behind a boiling, seething mass of lava and killing every thing down on Earth to the last bacterium.



So, nice going HuffPo. You’ve managed to once again mangle science and reality, adding to the already shameful articles about the Betelgeuse nonsense, and the nearly daily dangerous antivax and alt-med stuff.

Man. The least they could do is space this stuff out a little bit so I have time to breathe between debunkings.

Related posts:

Media FAIL (or, Superstorm followup)
Betelgeuse and 2012
Repeat after me: Apophis is not a danger

Repeat after me: Apophis is not a danger!

By Phil Plait | January 31, 2011 7:00 am

What is it with all the bad media reports of cosmic doomsdays? Betelgeuse last week, giant spaceships before that, and now Apophis. Sigh.

Here’s the scoop: I was tipped off about this by Jesse Emspak, who writes for the International Business Time (and who wrote a great article about the real opportunities represented by Apophis), and who told me about a Russian news site which, a few days ago, posted an article about the asteroid Apophis with the very menacing title, "Russian astronomers predict Apophis-Earth collision in 2036".

Sounds scary, right? One problem: it’s 100% utter crap.

Rock will roll on by

This guy won’t help.

First, the reality: Apophis is what’s called a near-Earth asteroid; it currently swings near our planet roughly every seven years. In April 2029 it will have an extremely near pass, getting so close it will actually be below our geosynchronous satellites! It will definitely miss us, but there’s a catch: if it passes us at just the right distance, Earth’s gravity will warp its orbit just enough that seven years later, Apophis will hit the Earth.

Let me be very, very clear: the odds of this happening are incredibly low, something like one in a 135,000. I fret about asteroid impacts, as you might imagine, but this one doesn’t worry me at all. The odds are so low I worry more about Snooki getting her own three-movie contract.

The reason the impact odds are so low, but not zero, is that we don’t precisely know Apophis’s orbit. There is a tiny region of space above the Earth called the keyhole, and Apophis has to pass right through it to have its orbit modified enough to hit us on the next path. We can’t know for sure if the rock will pass through the keyhole or not in 2029, but we can apply statistics and calculate that minuscule 0.0007% chance. And maybe it’s better to think of it as a 99.9993% chance it’ll miss.

Feel better?


OK, so what’s with that Russian news article? Besides the breathless — and totally wrong — headline, here’s the first line:

Russian astronomers have predicted that asteroid Apophis may strike Earth on April 13, 2036.

Bzzzzzt. While technically correct, this gives the strong impression that the odds of impact are high. That’s irresponsible journalism at best. Yet things quickly get worse:
Read More

Popular ways the Universe may kill us

By Phil Plait | August 26, 2010 10:30 am

popmechlogoMy friend Erin McCarthy works at Popular Mechanics. We met at Comic Con last year, and at this year’s nerdfest we chatted briefly about me possibly writing an article for them some day.

That day has come. On their website they’ve posted my short but deadly "Top 5 Ways the Universe Could Wipe Out Humankind". I wrote it a bit tongue-in-cheek — the topic sure lends itself to snark, doesn’t it? — but I had to scratch my head about it a wee bit. After all, what are the Top 5 ways? So I picked one that was statistically likely, two that weren’t, and two that were inevitable.

I bet you can figure out which was which. Anyway, they generously plugged my show in the article, and even embedded the teaser clip in the section about asteroid impacts.

I hope you like it. And thanks, Erin!

Bad Universe sneak peek!

By Phil Plait | August 24, 2010 10:25 am

baduniverse_bikinigaugeIn case you haven’t heard — and c’mon, do you live in some underground cavern with Morlocks and C.H.U.D.S.? — my new TV show "Phil Plait’s Bad Universe" premieres this Sunday night August 29, at 10:00 p.m. on the Discovery Channel (check your local listings; for me it’s on at 8:00).

This first episode is about saving the world from asteroid impacts. In most science TV shows on this topic they’re heavy on the death and destruction, but pretty light on what we can actually do about them. But if you’ve read my book Death from the Skies! you know I’m all about getting off our collective butts and doing something. So in "Bad Universe" we go step-by-step, looking into what can be done to keep an impact from ruining our whole day.

Wanna see a clip? Thanks to Discovery Channel, here’s a sneak peek!

[For a longer teaser of the show, go here.]

Did my stunt double survive? How much destruction did we wreak on the New Mexico desert? And what the frak can we do if we see some nickel-iron bucket o’ death headed our way?

Well, you’ll just have to watch the show and see, won’t you?

And if you think filming this show was fun… it was. And there’s lots more. Tune in and find out!

Oh, and before you go: tomorrow I’ll have another Twitter contest announcement, where I’m giving away lots of cool stuff connected with the show. Stay tuned!

For those who are curious: the picture at the top is me looking through what’s called a Bikini Gauge, named after the nuclear bomb tests in the 1950s (and not the swimsuit, though the latter does provide a lot of fodder for jokes if, like me, you have the sense of humor of a 15-year-old). The gauge measures how much pressure the shock wave from an explosion generates… and we had lots of them for the test. I won’t give away the results, but the measurements we got were not reassuring.

In Russia, Apophis impacts YOU!

By Phil Plait | December 30, 2009 11:43 am

Artist drawing of an asteroid entering Earth's atmosphereI don’t spend a lot of time worrying about actual asteroid impacts — I think about them, but the odds of a big impact are too low to panic about. We should be concerned, and absolutely we should take steps in case we find The Big One headed our way. But I sometimes wonder if I should worry more about our reactions to potential impacts. Or, more specifically, Russia’s reaction.

Apophis is an asteroid, a chunk of rock over 200 meters across orbiting the Sun. The problem is, the orbit of Apophis crosses that of the Earth. If the two are in the same place at the same time, well, bang! It’s big enough to blow up with the force of several of hundred megaton bombs. That’s not enough to wipe out life on Earth, but it’s certainly enough to do a whole lot of damage, and if it happens over a city… well.

In April 2029 Apophis will pass within a few thousand kilometers of the Earth’s surface. It won’t hit, but Earth’s gravity will change the orbit of the asteroid. If the asteroid passes us at just the right distance — in a region of space a few hundred meters across called the keyhole — it’ll swing back in seven years and hit us.

We don’t know the exact orbit of Apophis well enough to know for sure how close it’ll pass in 2029; we can only assign probabilities. The odds of it hitting the keyhole are pretty low, though: about one in 250,000 (downgraded from 1:45,000 recently as better orbital determinations were made).

Enter the Russian space agency. Anatoly Perminov, the head of the agency, was recently quoted in an AP news article that he wants to consider putting together a mission to move it out of the way, making sure it doesn’t hit. I’m all for that! What worries me is this quotation:

Without mentioning NASA findings [of downgraded odds of an impact], Perminov said that he heard from a scientist that Apophis is getting closer and may hit the planet. “I don’t remember exactly, but it seems to me it could hit the Earth by 2032,” Perminov said.

Now, I know he’s not an astronomer, but he does run a national space agency. I’d feel a whole lot better about his organizing a meeting to deflect this rock if a) he had the date right (it cannot hit before 2036, and the odds then are very low), and 2) he could actually, y’know, name his source.


Now, maybe he was misquoted by the AP. Or maybe it was out of context. And again, I don’t expect the head of the space agency to be on top of every detail; it could simply be an honest mistake with the date. But I am not particularly happy when someone in that position bases a decision at least partly because he heard it from some guy he knows but can’t remember who or when.

Did I say yikes before? Yeah.

I do think governments should take this seriously. I also know that as of right now, NASA is not taking this seriously enough. Perhaps if Russia gets this ball rolling, and other countries (like India, China, and Japan) join in, then NASA will be forced to take a better look at this situation. I know I was being a little snarky above (this is a blog, after all), but in the end some good may come of this. We just don’t know enough about asteroids and how to push them out of the way. We need to set up and fly missions to a few near-Earth asteroids to understand them better and add to our knowledge of their composition, structure, and behavior.

Theory is all well and good, but nothing beats some good practical experience. And while I dread the day when an announcement of a statistically significant likelihood of impact for a rock is announced, I’d be a whole lot happier and more comfortable if we had a dozen missions to asteroids already under our belt when that happens. Even if they got their start with this sketchy quote from the head of the Russian space agency.

Read more about this on Discover Magazine’s 80 Beats blog.


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