Exposing PseudoAstronomy

May 6, 2017

Podcast Episode 162: Geocentrism, Take 2


Geocentrism
Is so wrong, even young-Earth
Creationists know!

Slightly longer segment this time, a bit of a mishmash between episodes 78 and 152, young-Earth creationists refuting geocentrism. I go through about five different arguments against geocentrism and also look at the language that young-Earth creationists use to argue against geocentrists.

I added feedback to this episode again, almost catching me up, covering several varied topics including potential future episodes. There’s also an announcement about the episode schedule.

Geocentrism Cartoon

Geocentrism Cartoon

Advertisements

October 4, 2016

Podcast Episode 149: Modern Flat-Earth Thought, Part 2 (U.N. Flag and Airplane Flights)


“Modern Flat Earth Thought”
On maps, flags, and airplane flights …
Does it make sense? No.

Back to the flat Earth, this time discussing map projections and the United Nations flag, and then how some flat Earth proponents use and abuse airplane flight paths to argue that the planet is flat and looks just like the United Nations flag. I want to thank Michael R. (@SkepticalBelg on Twitter) for for reviewing and making several corrections to my text on how the airline industry works.

This was a particularly long episode, nearly a full hour. I also recorded this in a hotel room, and it sounds like I was too close to the microphone and at an angle at times and the room echoed, so my apologies for the audio quality in this episode. It was still better than the audio in the last episode, which was recorded on a phone outside, but it’s not perfect.

There are three additional short segments in this episode, the first being logical fallacies (detailing the argument against antiquity), second being feedback (the correction(s) from Episode 147), and the announcement to thank Michael.

Flat Earth Graphic

Flat Earth Graphic

September 17, 2016

Podcast Episode 147: The Hollow Earth According to David Icke


The hollow Earth … Sigh.
David Icke hasn’t met a
Crazy he don’t like.

Continuing on the theme about the structure of the planet, I take a look at something not talked about for 139 episodes: The Hollow Earth. In this particular case, I take a look at the claims about the hollow planet made by conspiracy guru David Icke.

As mentioned in this post, I was recently on an episode of Cognitive Dissonance where I had read chapter 12 of David’s 1999 book, “The Biggest Secret.” We discussed a lot of the conspiracy in the chapter but only tapped the topic that made up about 25% of the chapter, David’s claims about Earth being hollow. Since I spent so much time reading his nonsense, and I took notes, and I even highlighted (in 4 different colors!!!!), I had plenty of material to get a podcast episode out of it, and … here it is!

There are three other segments beyond the main one: Logical Fallacy (focusing on the Gish Gallop), Feedback (going back to episode 145 to try to explain a few things in easier terms), and mentioning people who have left iTunes reviews since the last time I mentioned them (back in December 2015).

I hope that you enjoy this episode.

P.S. Already a correction that I’ll mention in the next episode: I incorrectly stated that if you’re inside Earth, you would not be pulled to the inner surface of the shell, you would be pulled to the center. This is incorrect. The Shell Theorem holds that any particle inside of a perfectly symmetric sphere would experience an even force of gravity, everywhere, such that if you placed yourself anywhere inside the sphere, you would stay there. David Icke is therefore still wrong, but my explanation of what would happen was not correct.

Hollow Earth Image with Hole at Pole

Hollow Earth Image with Hole at Pole

September 5, 2016

Podcast Episode 145: Modern Flat Earth “Thought,” Part 1


“Modern Flat Earth Thought”
Might be a contradiction
Of terms, but let’s see!

Back from hiatus, a roughly 45-minute episode on a few ideas promoted by the very new (since about 2014) breed of flat-Earth proponents. I go into depth on human perception and then focus on both Earth’s curvature and the overall shape of the planet. This Part 1 exclusively features clips from Eric Dubay, but future episodes will include other luminaries in the movement.

There are three other segments beyond the main one: Logical Fallacy (focusing on the False Dichotomy), Feedback (from James F. related to the Ringmakers of Saturn by Norman Bergrun), and a brief announcement.

For those returning listeners, thank you for sticking with the podcast through the very long hiatus. For those new listeners, thanks for checking it out.

I hope that you enjoy this episode.

October 25, 2013

Planetary Orbits and Terms, 101


Introduction

I’ve been made aware lately that some people who profess certain types of pseudoscientific beliefs, such as Mars’ orbit being ridiculously eccentric (highly elliptical), do not understand basic orbital terminology and geometry.

With that in mind, I thought this would be a good post not only because of that, but also towards a general explanation of terms for people who hear them from time-to-time who may not have known what they meant. I should also probably mention (normally goes without saying) that these are basic terms and definitions and are not unique to me and are not unique to any given field.

Terms! (Vocab Words!!)

Some geometry terms, parts of an ellipse:

  • Major Axis: The longest axis of an ellipse (goes through the center).
  • Minor Axis: The shortest axis of an ellipse (goes through the center).
  • Foci/Focus(es): All ellipses have two foci, or two “focuses.” The foci have the property (or ellipses have the property) such that if you add the distance between the point and each focus, every point along the ellipse will have the same distance. This leads to the “pins and string” method of drawing an ellipse. In a circle – a special form of an ellipse, the two foci are in the same location, the center.
  • Center: The point exactly between the two foci. And the intersection of both the major and minor axes.
  • Eccentricity of Ellipse: Always between 0 (a perfect circle) and 1 (a line). It is defined as the SQRT(1-(minor/major)^2).

Some astronomy terms, parts of an ellipse:

  • Semi-Major Axis: Half the longest axis of an ellipse (starts from the center or edge, goes to the edge or center).
  • Semi-Minor Axis: Half the shortest axis of an ellipse (starts from the center or edge, goes to the edge or center).
  • (Primary) Focus: In the solar system, the sun is at one focus of the ellipse for all planetary orbits, and there is nothing physical in the second focus. For moons orbiting planets, the “primary” focus is the planet, there is nothing physical at the other focus.
  • Eccentricity of Orbit: Eccentricity of an orbit is typically defined as: (apoapsis – periapsis) / (apoapsis + periapsis).
  • Ellipticity: Rarely used, sometimes confused with eccentricity. Ellipticity is just major/minor axis and is always a value greater than 1 (1 = circle). A value of 2 would mean the major axis is twice as long as the major axis, though in this case the eccentricity would be 0.87.

Some astronomy terms, other parts of an orbit:

  • Peri-: Prefix meaning “closest.” If you’re a planet on an orbit around the sun, your perihelion is the closest approach to the sun. If you’re around Earth, it’s perigee, moon is perilune, Jupiter is perijov, and I’m sure there are others. Generic term for any body is “periapsis.” Periapsis can be calculated as the semi-major axis multiplied by (1-eccentricity).
  • Apo-/Ap-: Prefix meaning “farthest.” If you’re a planet on an orbit around the sun, your aphelion is the farthest approach from the sun. If you’re around Earth, it’s apogee, moon is apolune, Jupiter is apojov, and I’m sure there are others. Generic term for any body is “apoapsis.” Apoapsis can be calculated as the semi-major axis multiplied by (1+eccentricity).

Some perspective terms. These are visual things, as viewed from one object relative to another. Formally as parts of an orbit, for orbital mechanics, they are irrelevant.

  • Conjunction: When one object appears at the same location in space as another object, as seen from a third object. For example, when viewed from Mars, if the moon Phobos appears in front of the sun (so you get an eclipse), then this is a conjunction.
  • Inferior Conjunction: When the conjunction happens such that the object conjuncting is physically “in front of” the other object as seen from the third. In the previous example, a moon creating a solar eclipse (blocking part of the sun) is always in an inferior conjunction with the sun.
  • Superior Conjunction: When the conjunction happens such that the object conjuncting is physically “behind” the other object as seen from the third. In the previous example, when the moon creates a solar eclipse (blocks part of the sun), the sun is in superior conjunction. As another example, when Mars appears to go behind the sun as seen from Earth, and so we can’t get any data back from spacecraft, Mars is in superior conjunction.
  • Opposition: When one object appears in the opposite location in space as another object, as seen from a third object. For example, when viewed from Earth, a full moon is in opposition to the sun, because as the sun sets, the full moon rises, so they are directly opposite each other in the sky.

As a matter of orbital mechanics, an inferior planet (one inside Earth’s orbit) can never be in opposition with the sun. And, as a matter of orbital mechanics, a superior planet (one outside Earth’s orbit) can never be at an inferior conjunction with the sun (appear between Earth and the Sun).

Applying These Terms

Let’s look at Earth’s orbit. Earth’s perihelion is 147 million km, the aphelion is 152 million km. The eccentricity is therefore 0.017 ((152-147)/(152+147) = 0.017). The major axis is aphelion+perihelion = 299 million km. The semi-major axis (what’s often quoted as Earth’s “average distance” from the Sun) is 299/2 ≈150 million km.

Notice that these have nothing to do with conjunction or opposition — by definition, and in practicality, they cannot, because opposition and conjunction requires three objects, not two. Earth and the sun could be in conjunction or opposition from a given third object / vantage point at any time regardless of where Earth is in its orbit.

Applying These Terms to Mars

We have a bit more we can do here if we consider Earth’s vantage point when looking at Mars and the Sun.

As before, we can look at its orbit in isolation, independent of Earth, because looking at it in some other way does not make any sense. Mars’ perihelion is about 207 million km. Mars’ aphelion is about 249 million km. (By the way, these two bits of data are available pretty much anywhere online, but I tend to use the very basic table at NASA’s Planetary Fact Sheet.) With those two numbers, we can calculate others. For example, Mars’ eccentricity is easily calculated to be 0.094: (249-207)/(249+207)=0.09. Much larger than Earth’s, but not as large as Mercury’s (0.21) or Pluto (0.24) or most comets and even Earth-crossing asteroids. We can also calculate its semi-major axis: (249+207)/2 ≈ 228 million km, which is what NASA lists as the distance from the Sun of Mars.

We can also look at the terms opposition and conjunction. Opposition is when Mars appears opposite in the sky relative to the sun. Physically, this happens with Sun-Earth-Mars would appear in a line to someone looking down/across/up towards the solar system. This means Earth can be any distance from the sun (between its perihelion and aphelion) and Mars can be any distance from the sun (between its perihelion and aphelion). It doesn’t matter. However, Earth and Mars, along their orbits, are the closest they will ever get. This means that Mars opposition means Mars will be anywhere from 102 million km from Earth to 55 million km from Earth (a factor of nearly 2 difference!). This is calculated simply by taking Mars’ aphelion minus Earth’s perihelion (249-147=102) and Mars’ perihelion minus Earth’s aphelion (207-152=55). As in, the closest, physically, that Mars can be to Earth is when opposition just happens to coincide with when Mars is at its perihelion and Earth is at its aphelion. The farthest, physically, that Mars can be from Earth during opposition is when opposition happens to coincide with when Earth is at aphelion and Mars is at aphelion.

Conjunction is when Mars appears at the same spot in the sky relative to the sun. Because it’s a superior planet (outside Earth’s orbit), it can only be in superior conjunction (on the opposite side of the sun as from Earth). This means that, during opposition, Mars can be anywhere from 354 million km to 401 million km from Earth. This closest would be when conjunction just happens to coincide with when both Earth and Mars are at perihelion; the farthest is when conjunction happens when both are at aphelion.

With all that in mind, practically speaking, the distance between Earth and Mars during conjunction and opposition varies from event to event. Because each have different years, while perihelion and aphelion tend to happen at the same longitude in their orbit (time of year — as in perihelion for Earth is in January every year, so aphelion is in July every year), the time of year that opposition and conjunction occur vary from event to event.

Earth and Mars orbiting the sun.

Earth and Mars orbiting the sun.

This is shown to some extent in this animation from Wikipedia. You can see how oppositions and conjunctions will vary from year-to-year and that the distance will, as well, given Mars’ orbital distance changing much more than Earth’s.

Some may remember back in July 2003 when opposition happened almost exactly when Earth was at aphelion and Mars at perihelion. It was widely reported, such as in this NASA press release, and it’s been widely hoaxed since then. Opposition since 2003 has not been as bright because Mars has not been as close to its perihelion and Earth has not been as close to its aphelion. They won’t line up again like that for roughly 60,000 years.

Application

This has been a lengthy explanation, but I hope that I’ve explained everything clearly by this point. Importantly, one should not confuse opposition with perihelion, and one should not confuse conjunction with aphelion. After all, Mercury and Venus cannot be in in opposition, ever, and yet both have perihelion and aphelion points, by definition.

For those wondering where this is coming from, well, back in 2011, I wrote a lengthy post about some of Mike Bara’s claims, and the last one was his definition of an ellipse. He claimed that Mars has an orbital eccentricity that is very high. Specifically, he wrote, “In fact, Mars’s orbit is so eccentric that its distance from Earth goes from 34 million miles at its closest to 249 million miles at its greatest.” Mike uses this as evidence to support his idea that planets are birthed in pairs, flung off via fission from the sun.

What he was referring to was the average distance between the two during opposition and conjunction. Which, as I’ve just explained (and explained with diagrams in that post), has nothing to do with perihelion and aphelion, which are how you get eccentricity. Opposition and conjunction have nothing to do with aphelion and perihelion. More recently on his blog, he has attacked me while defending his claim that Mars is on a highly eccentric orbit. Note that I never said Mars’ orbit is not eccentric (see 3 paragraphs below: “Except …”). It has the second-highest eccentricity of any planet (since Pluto is not a planet). It’s half as eccentric as Mercury yet around 6 times as eccentric as Earth’s. But, it’s 0.09 because of its min and max distances from the Sun, not its min and max distances from Earth.

Venus has the lowest eccentricity of any planet (0.007), and yet its minimum distance from Earth (its aphelion, our perihelion) is a mere 38 million km, and its farthest distance from Earth (both aphelion) is 261 million km, a factor of almost 7 difference.

But, getting back to what Mike versus I wrote, Mike wrote: “Now, let’s examine your statement that “It’s really simply incredibly stupid of Mike to claim that Mars’ orbit is highly eccentric.” Oh really?” Mike then goes on to point out that its orbit is the second-highest eccentricity-wise. And then wrote: “Excluding Pluto, which is no longer considered a planet, Mars orbit is the 2nd most elliptical of all the “planets.” You can see from the graph that it is far more eccentric than Earth’s, exactly as I characterized it. Put another way, Earth’s relative distance to the Sun varies by only about 3.1 million miles in the course of one orbit (year). Mars’ orbit, by contrast, varies by as much as 26.5 million miles over the course of a Martian year. Obviously, Mars’ orbit is more eccentric by an order of magnitude. How Stuart fails to grasp this I do not know. Maybe he’s just stupid.”

Except, what I wrote is quote-mined in that context. What I wrote, if you go to my original post, was this: “It’s really simply incredibly stupid of Mike to claim that Mars’ orbit is highly eccentric because it comes as close as about 0.38 A.U. (“astronomical unit” is the distance between the sun and Earth) but goes as far as 2.67 A.U.” Given the diagram that accompanied that text, it was clear those numbers are relative to Earth. I stand by that statement when it’s read in full context. It’s not eccentric because of its distance from Earth during opposition versus conjunction, it’s eccentric because of its distance from the sun during aphelion and perihelion. In fact, when calling me stupid for not grasping Mars’ eccentric orbit, Mike directly quotes the numbers that support what I stated and not what he did.

Final Thoughts

I suspect that if Mike reads this, he will still claim that I am mistaken somehow. It’s odd that he would fight so much over something so trivial instead of just admitting he made a mistake and moving on. After all, he claimed later in his attack that it’s not even important to his overall point.

Why then am I devoting time to pointing out and not moving on from something so trivial? Because I consider this to be the heart of this blog and what I do as education and public outreach: Using a real-life example of where someone goes wrong in their thinking to teach something. In this case, I had the context to get into some basics of orbits and definitions that people don’t often learn or remember if they had learned it. And, with the idea of how NOT to apply these terms, I find that people usually better remember how to use them correctly.

But, I don’t expect Mike to agree. Why? Well, his latest is that he’s promoting his new book, “Ancient Aliens on Mars” (there, Mike, I gave you a plug). He has put up a Picasa album with, I presume, images from the book (considering that’s the title of the album). In the second set of five images, he goes over ellipses. With specific notes to me. And, makes the same, fundamental mistakes. Including one figure labeled “”Perihelion” or Opposition” with the caption “Explanation of Mars Opposition, for Stuart Robbins.” And, there is another image showing “Aphelion” which just shows conjunction, and it has been captioned “Pay attention Stuart.”

Yup, I paid attention, and Mike, you’re still wrong in your terms and definitions. And I have been much more polite about it than you.

February 1, 2013

Podcast #63: Clip Show #1


It was bound to happen at some point, that episode that’s just a hodgepodge of short, random bits of crä-crä that I put together as a clip show. This one features five bits of silliness — or maybe six, I lost count. Big-name stars you may remember from other episodes are Brooks Agnew and Gregg Braden, but making their first time appearance we also hear from Christopher Knight and Alan Butler, Ken Parsons, and Jeffrey Grupp. Coast to Coast AM clips feature heavily, so if you don’t like ’em, you may want to skip this episode.

Other segments were Announcements and a Puzzler. You’ll need to go to about 24 minutes into the episode for the puzzler, it’s not in the usual place.

November 16, 2012

Podcast Episode 55: Interview on Extraterrestrial Life with Dr. Brian Hynek


This nearly hour-long interview on a just-over one-hour episode is with the V-est of VIPs, my boss and former thesis advisor, Dr. Brian Hynek.

Brian is a professor in geological sciences at the University of Colorado, Boulder, where he studies Mars with a focus on understanding how and when Mars could have been habitable by life as we know it. This research program includes studying craters (me!), valley networks, other evidence for water, and traipsing around Earth for analogues for Mars, including studying extremophiles on active volcanoes.

The interview is mostly main-stream, covering a lot of the basics, but we get into some of the “PR Fails” of NASA, including the GFAJ-1 “arsenic” bacteria from two years ago and the ALH84001 Martian meteorite “nano-bacteria.” And, no discussion about Mars would be complete without a Hoagland name-drop once or twice.

Since this is an interview episode, and since it’s an hour long, only the Puzzler segment is present in addition to the main interview.

November 12, 2012

Falling through Earth

Filed under: general science,movies,physics — Stuart Robbins @ 8:18 pm
Tags: , , , , , ,

Just a quick post for today (busy busy here as usual, stuff should settle down a bit come December …). What would it be like to take an elevator trip through Earth from one side to the other?

Apparently, in the remake of the hilariously (poor science-)fiction movie Total Recall, the remake which I have not seen, there is a plot point of taking an elevator trip through Earth’s center from one side of the other. Apparently this is the only way to safely travel from one city to the other … I hope it’s not just some stupid thing that seems “cool” that serves no other purpose than to spend a budget on special effects.

Anyway, I came across a Wired article today where a physicist spends great detail explaining what would it actually be like to travel through Earth’s center. As with all great investigations when we have too much time on our hands, he even does numerical simulations, though it looks like he graphed in Excel … but I won’t hold it against him.

He shows several interesting things, including that the elevator would reach speeds no slower than 8 km/sec (around 5-6 miles/second). That’s really really fast. If he includes the higher density of Earth’s core, then you reach speeds up to 50% faster than that, even.

He also addresses the concept of weightlessness. This is something that all physics majors learn about in detail in Classical Mechanics classes (Physics I on steroids after your first and usually second year). But, I’ve always found it somewhat difficult to easily convey why, without drawing diagrams of circles and triangles, you would be weightless if you were stationary at Earth’s center. He goes through that in agonizing detail before letting you know that, actually, in the scenario in this version of Total Recall, you’d be weightless the whole time because you’re in free fall.

So, as I said, quick post for today, head over to Wired if you have a few minutes to reach about the physics of taking an elevator trip through the Center of the Earth.

April 11, 2010

What Happens When All the Planets Line Up Against Us?


Introduction

This is a claim that has persisted for a long time, and though people who believe in the 2012 stuff have propagated it, it is not specifically a Planet X / 2012 claim: If all the planets (plus our moon) lined up opposite the sun, they would pull us out of orbit. As the “lolcatz” say, “Oh noez!”

Gravity

The force felt by an object due to gravity is a very simple mathematical function, codified by Newton’s Universal Law of Gravity:

In this equation, F is the force felt, G is the Gravitational Constant, M m are masses of the two objects in question, and r is the distance that separates them.

To figure out how much more or less two different objects will pull on the same object, we can simply remove one of the two masses, so the equation simplifies to F = G * m / r2.

The Math

To determine the relative forces, one simply needs to know the mass of the planets and sun, and the distances between Earth and those objects. This can be found in any basic astronomy textbook or online source. One then can simply plug in the numbers and figure out the forces.

For the sake of argument, let’s say the sun is on one side of this tug-of-war, and the moon, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, and even Pluto are all on the other (Venus and the sun don’t count ’cause they would have to be on the sun’s side). Let’s calculate the force first due to the sun:

Object
Mass (1024 kg)
Distance from Sun (106 km)
Distance from Earth (106 km)
Relative Force
Sun 1,989,100 149.6 0.0059

Alright, now let’s do all the rest, remembering that for the planets, we’ll need to subtract out the distance between Earth and the sun from what are commonly quoted as the planets’ distances:

Object
Mass (1024 kg)
Distance from Sun (106 km)
Distance from Earth (106 km)
Relative Force
Moon 0.07349 0.3844 3.32·10-5
Mars 0.6419 227.9 78.32 6.98·10-9
Jupiter 1,899 778.6 629.0 3.20·10-7
Saturn 568.5 1434 1284 2.30·10-8
Uranus 86.83 2872 2723 7.82·10-10
Neptune 102.4 4495 4345 3.62·10-10
Pluto 0.00125 5906 5756 2.52·10-14
Ceres 0.00095 415 265.4 9.00·10-13

Final Thoughts

This is a really short post because it doesn’t need to be long. To be perfectly honest, I was actually surprised at how small the force of Jupiter actually is on Earth relative to the sun. If we add up the force from all of the other objects, we only get a force that is 0.566% as strong as the sun’s. And then if we take the moon out of the equation because that would be the first to move out of the alignment, then we have a force of only 0.000592% as strong as the sun’s.

If we look at Venus if it were also lined up, helping the sun, its force is 1.90·10-7, or about half as much as all the other planets (again, leaving out the moon), so it would cancel 54% of the effect of all those other objects (again leaving out the moon). The force from Mercury is only about 1/3 that of Mars.

So really, if anyone who makes this claim were to bother to spend about 10 minutes looking up the numbers and plugging them into an Excel equation (what I did), they would quickly see that this claim is simply and utterly nonsense. And this is besides the fact that the planets aren’t lining up any time soon on the other side of Earth to try to pull us out of orbit.

Create a free website or blog at WordPress.com.