Bad Universe on the Discovery Channel

[bokonon]

So the geometry is that you're looking towards the Sun, in the plane of the orbits of the (true) planets?

If so, then the Main Belt asteroids do not form a disk, certainly not one whose scale height is approx the same as that of the planets!

Toward the sun, or away from it, either way.

The "scale height" of the asteroid belt is (according to the source I cited) 1 foot, a number he claims Phil agrees with. That's with the Earth being a 2mm bead, and Jupiter being a 22mm marble. That's why I was using a square foot view window. I guess we could assume that the asteroids would be denser toward the vertical center of that window, but even so, as you've noted, we're not looking at anything that resembles a floating avalanche.

 

[Mister Earl]

Keep in mind, the show is kind of aimed at educating the layman. Without an overabundance of rocks, how would the viewer know that it's supposed to portray the asteroid belt in a quick glance? I look at it as kind of... a visual metaphor to speed things along.

 

[Wowbagger]

You know, there's even a part of the show where Phil Plait is depicted as a comic book character, but he should really know better! Phil is NOT a comic book character, he's a real person!! Talk about embarassing inaccuracies!

 

[technoextreme]

Yeah, it seems that a laser is probably the most technically challenging way of moving an asteroid (at least with current technology).

I use a 193 nm laser to blast holes in rocks in the lab, but the beam only travels about a meter and only blasts a hole about 100 um across. Not quite potent enough for space applications (but fun to use, nonetheless).

I thought the entire point was that we can chuck thousands of the little buggers into space.

 

[jadebox]

2)While the science presented is fascinating, I found the display of the ejecta cloud after an impact to be all wrong (I think!). The small particles wouldn’t rotate with the asteroid but continue out in a straight line from wherever it was ejected. And depending on the impact speed it would be easy for them to reach escape velocity, thus not staying too close to the rock.

The animation is correct (at least as far as the rotation).

Think about it this way: From the asteroid's viewpoint, there is no rotation.

It's like when you look up at the night sky. You see the stars moving above. If you set off an explosion on earth, the ejecta goes straight up (from your view point). From an observer off the earth that is stationary with respect to the sun, for example, the ejecta would appear to rotate with the earth.

Another way to consider it is that the animators could have positioned the virtual camera at a point that rotates with the asteroid so that you are always looking at the same point on the asteroid and it no longer appears to rotate. Wouldn't it look funny if the ejecta rotated around the asteroid after the impact? That's what you are suggesting it would do.

-- Roger

 

[Skeptic Ginger]

I was disappointed. For years Plait has been criticizing those who profit by spreading fear through sensationalism. He outdid even them as he was grinning ear to ear over the prospect of creating explosions. It was another example of the dumbing down we’ve seen in recent years by once respectable cable networks such as Discovery and History.

I think you are confusing sensationalizing bad science vs sensationalizing good science.

We want to market good science. Phil and the rest of the skeptical community media stars have been saying for years we need to make science desirable.

I think you might want to rethink what the real goals are here and ask yourself why is making science fun wrong? If you market something good, is that the same as marketing something bad?

 

[Skeptic Ginger]

Keep in mind, the show is kind of aimed at educating the layman. Without an overabundance of rocks, how would the viewer know that it's supposed to portray the asteroid belt in a quick glance? I look at it as kind of... a visual metaphor to speed things along.

Perhaps that is legit. A foot'note' might have helped though. Phil could have snuck a comment in there about what the real asteroid belt looks like, or a short segment on the real distances in space.

 

[Skeptic Ginger]

You know, there's even a part of the show where Phil Plait is depicted as a comic book character, but he should really know better! Phil is NOT a comic book character, he's a real person!! Talk about embarassing inaccuracies!

That's different, WB. With the exception of little kids, people know when they see cartoon heroes that real men aren't V shaped. So the cartoon can be translated in one's brain into the real person it symbolizes.

The crowded asteroid belt, OTOH, is a known myth to astronomers, but not to the lay public. Phil even has a Bad Astronomy paragraph or two on his website that indirectly addresses the myth.

Tons of Asteroids

...That number does not even take into account the fact that the orbits of the asteroids are tilted with respect to one another, so really, instead of an area, you need to think about the volume of space. Dr. Durda tells me that there are about two million kilometers on average between asteroids.

There may be a lot of asteroids out there, but space is BIG!

Surprisingly, the total mass of asteroids, even though there are so many of them, is quite small. All of the asteroids combined weigh less then our own Moon. A billion asteroids 100 meters or larger sounds like a lot, but that's misleading. The volume of an object goes as the cube of the radius. A billion asteroids 100 meters across would occupy the same space as a single asteroid with a radius of the cube root of one billion times 100 meters. This is equal to 100,000 meters, or 100 kilometers across. That's pretty small!

A crowded asteroid belt image IS BAD ASTRONOMY!

 

[arthwollipot]

Perhaps that is legit. A foot'note' might have helped though.

"...but with an asterisk!"

 

[LarianLeQuella]

If I'm ever...ever... interviewed on any subject I want a big phallus shaped cloud in the background.

I thought one of them was more mushroom cloud like.

Give my very low opinion of the average American's interest and understanding of science, the show was very enjoyable. I'm sure Dr. Plait would have prefered to do some things differently, but I liked it.

 

[alfaniner]

The animation is correct (at least as far as the rotation).

Think about it this way: From the asteroid's viewpoint, there is no rotation.

It's like when you look up at the night sky. You see the stars moving above. If you set off an explosion on earth, the ejecta goes straight up (from your view point). From an observer off the earth that is stationary with respect to the sun, for example, the ejecta would appear to rotate with the earth.

Another way to consider it is that the animators could have positioned the virtual camera at a point that rotates with the asteroid so that you are always looking at the same point on the asteroid and it no longer appears to rotate. Wouldn't it look funny if the ejecta rotated around the asteroid after the impact? That's what you are suggesting it would do.

-- Roger

Interesting, but that assumes that the particles have not reached escape velocity. It seems unlikely that the dust would achieve a stable orbit. It should be ejected, then keep on going in a straight line, right?

 

[Brown]

What really sucks about the show is that my satellite provider in Canada doesn't show it. Oh, we get something called the Discovery channel, and on it we get "Mythbusters" and some of the other Discovery stuff, but nothing that has "Plait" or "Universe" in the title.

So... having seen exactly zero seconds of the show, I have an opinion about it.

The topic is too broad.

From my early grade school days, I was taught that one of the principles of a good presentation is not to get too broad. Pick a fairly specific topic, and stick to it. I mean, geez, is there any topic that ISN'T broader than the Universe??

 

[jadebox]

Interesting, but that assumes that the particles have not reached escape velocity. It seems unlikely that the dust would achieve a stable orbit. It should be ejected, then keep on going in a straight line, right?

Even if the particles reached escape velocity, they would still go the directions shown in the animation. The particles are traveling in straight lines. They are not orbiting the asteroid. It does kind of look like the particles are frozen around the asteroid, but I think the animation is trying to show them as going up and falling back down (like a fountain).

I'm not sure if the particles should actually reach escape velocity or not, though.

-- Roger

 

[LarianLeQuella]

So... having seen exactly zero seconds of the show, I have an opinion about it.

The topic is too broad.

Actually, it seems to be structured on his book Death From the Skies. So the first chapter was about meteor strikes. I don't have the book in front of me, but I think chapter 2 was supernovas. So the title of the show is borad, the subject is "How the universe can kill us on this planet, and what we can do to stop it, or if we even need to worry about it."

 

[Dr.Sid]

I wont give any details .. but come on people .. it's year 2010 .. there are means how to watch shows not aired in your region.

 

[alfaniner]

Even if the particles reached escape velocity, they would still go the directions shown in the animation. The particles are traveling in straight lines. They are not orbiting the asteroid. It does kind of look like the particles are frozen around the asteroid, but I think the animation is trying to show them as going up and falling back down (like a fountain).

I'm not sure if the particles should actually reach escape velocity or not, though.

-- Roger

There are four ways the ejecta could be moving with respect to the asteroid. Back toward the asteroid. In stationary (geosynchronous) orbit. In non-synchronous orbit. Away from the asteroid.

For any orbit it is highly unlikely that each particle would achieve the correct velocity. I also doubt the gravity of even a very large asteroid (up to several kilometers) would be enough to prevent escape velocity. Thus, a particle ejected would keep on going in the direction it first escaped (albeit perhaps with some minimal influence from the asteroid's gravity at first.)

 

[Kuko 4000]

Just watched it. I thought it was nicely done and interesting, Phil looks and sounds good on TV. Imo the editing guys left too many holy-somethings to the final cut, but his signature "Holy Haleakala" is great Looking forward to the other two episodes - if they are as good as or better than the first one I hope it gets a regular spot! If you like the show remember to contact the channel with your comments, not sure if this is the best way to do that, but here goes:

http://corporate.discovery.com/contact/viewer-relations/


Also:

http://blogs.discovermagazine.com/badastronomy/2010/08/31/a-few-more-bad-universe-reviews/

A lot of folks are asking when it will play in their country. I don’t know, except that Discovery Asia will air it in November, and Discovery Canada is looking into it – and that latter was due to people on Twitter asking them. So don’t ever think you can’t influence what gets aired on TV, folks. Power to the Tweeple!

 

[Perpetual Student]

Maybe it had some entertainment value for some people, but for me it was an embarrassing waste of time for something that was supposed to be a popularization of science.

 

[Kuko 4000]

The main points I (a person with next to no previous knowledge about the field) picked up from this:

The threat from the skies is real.

The asteroids and comets speed along a lot faster than a bullet.

We are on a near collision course with a big rock and it could hit us in about 15-20 years (they gave a more precise date, but I can't remember it) if we don't do anything about it.

If an object is coming from the direction of the sun, we have pretty much no chance of knowing about it before it's too late.

Comets can change their course unexpectedly.

An object the size of a beach ball can kill people two miles away from the impact crater.

There's surprisingly few people seriously monitoring the skies compared to the threat.​

The question is, is the info accurate?