Starship Asterisk*

Beyond wrote:Hmm... 3-APODS today. When was the last time Otto Posterman was oiled

Beyond wrote:
Hmm... 3-APODS today.

When was the last time Otto Posterman was oiled

Nest wrote:I just looked up the reference for the 750 lightyears distance, but there it says 467 parsec = 1523 lightyears. I'm an astronomical amateur, so if anybody has an explanation, I'd be grateful. Im just asking because I wanted to add/correct wikipedia on this.

geckzilla wrote:

Nest wrote:I just looked up the reference for the 750 lightyears distance, but there it says 467 parsec = 1523 lightyears. I'm an astronomical amateur, so if anybody has an explanation, I'd be grateful. Im just asking because I wanted to add/correct wikipedia on this.

I've noticed that distance as well as size estimates for various objects seems to vary quite a bit from one study to the next. Who could say which is correct? There's a lot of room for errors. Still, the Wikipedia article seems more reasonable than the APOD description.

Nest wrote:Thanks, I was confused, because an old version of wikipedia (german) also said 750, and maybe the factor of 2 is might have a meaning. So I'll better not touch it.

NoelC wrote:Blue Sadr is not. False color this is, hm?

Nest wrote:I just looked up the reference for the 750 lightyears distance, but there it says 467 parsec = 1523 lightyears. I'm an astronomical amateur, so if anybody has an explanation, I'd be grateful. Im just asking because I wanted to add/correct wikipedia on this.

Ann wrote:The Hipparcos measurements, on which Jim Kaler based his distance estimate, said that the parallax to Gamma Cygni is 1.78 ± 0.27 milliarcseconds...

2) If - and that's a very big if - the Hipparcos measurements are absolutely correct, then the distance to Gamma Cygni is 1830 ± 280 light-years.

Chris Peterson wrote: There is little evidence of systematic errors in Hipparcos measurements

http://en.wikipedia.org/wiki/Pleiades#Distance wrote:

Measurements of the distance have elicited much controversy. Results prior to the launch of the Hipparcos satellite generally found that the Pleiades were about 135 parsecs away from Earth. Data from Hipparcos yielded a surprising result, namely a distance of only 118 parsecs by measuring the parallax of stars in the cluster—a technique that should yield the most direct and accurate results. Later work consistently argued that the Hipparcos distance measurement for the Pleiades was erroneous.[3][4][5][15][16] In particular, distances derived to the cluster via the Hubble Space Telescope and infrared color-magnitude diagram fitting favor a distance between 135–140 pc.[3][15]

Ann wrote:I have been a little suspicious of the Hipparcos data ever since the Pleiades controversy occurred.

rhorvitz wrote:
In this photo of Gamma Cygni, many stars in the surrounding star field seem to form short chains of 8-12 stars. There are enough of these that I wonder: is this an illusion or artifact, or is it the result of an actual physical process?

http://blogs.discovermagazine.com/badastronomy/2009/04/21/pareidolia-poser/#.Ue_eWazNk5Q wrote:

[b][color=#0000FF][size=150]Question for you: which of these two images shows dots that are placed at random, and which does not?[/size][/color][/b]

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Pareidolia poser
By Phil Plait, Bad Astronomy, April 21, 2009 7:26 am

Question for you: which of these two images shows dots that are placed at random, and which does not?

<<The problem with questions like this is that you already know it’s the one on the left that’s random, and the one on the right isn’t, since you know I’m trying to trick you. But what’s going on?

Our brains love to find patterns in random noise. Look at the clumping of the dots on the left; surely that’s not random? But it is. The distance between dots will average out to some number, but statistically you expect there to be some deviation from that average, so that some dots will be closer together (making clumps) and some farther apart (making voids). That’s what’s happening on the left.

On the right, the random pattern that was generated was modified so that the dots would not be too close together. If a dot’s position was found to be too close to another, its position was redone until it was a minimum distance from all other dots. What’s left is a pattern that we think looks more random, but is in fact highly non-random.

A more detailed explanation of these images is at the blog In The Dark, and he uses it to talk about galaxy distributions. However, it also tells us a lot about our brains. We are instinctively lousy at statistics.

Another great example is this one: imagine you flip a coin ten times, and you keep track. Which of these sequences is more likely?

HHHHHTTTTT

or

TTHHTHHTTH

The answer is they are both exactly as likely. You have a 50/50 shot at a heads or tails on each throw, so any 10-throw sequence is just as likely as any other! But we look at the second sequence and see no information in it. We assume it’s just random, and therefore more likely than a sequence where we perceive there is information, like five heads in a row followed by five tails. But each is just as likely.

We view the entire Universe through our senses, and the data are processed by our brains. This gloppy computer is highly sophisticated, but also highly unreliable to give us unbiased information. We see patterns where they don’t exist, we see cause where they may be none, and we see intent where there may be randomness.

That’s why pareidolia — seeing faces or other familiar objects in random patterns like oil stains, wood grain, and the odd piece of bark of pastry item — cracks me up. The brain of a human will interpret that pattern into something familiar, and if that person is religious, they see a religious icon. But they don’t seem to hang the same connotation on seeing Abe Vigoda in a nebula and Lenin in a shower curtain, or Ben Grimm in a supernova, or any of a hundred examples I can find easily.

You can be fooled. Remember that, always. It pertains to a lot in life, and a lot in the life of an active skeptic. Fooling people is easy. Getting them to see? That’s what’s hard.>>