APOD: Star Size Comparisons (2013 Jun 06)

[ro-star]

Am I the only one to recognize that the moon was rotating?? The moon does not rotate on its axis. We are presented with the same face of the moon at all times. Hence the saying..."Dark Side of the Moon"

the moon rotates on its axis at the same rate that it orbits the earth so one orbit = 1 rotation; this special case is called tidally locked, and is the case for all major moons in the solar system, such as Callisto, Ganymede, Io, Titan and so on, in fact all these I enumerated here are bigger than our moon;

[rstevenson]

New Rule: If you're going to start a post with "Am I the only one to recognize that...", you should stop and do a little research. Because you shouldn't be the only one to recognize something, unless you're a leading expert in the field.

Rob

[waterlrl]

The video gives the impression that the Sun is a small star. This is not so. The Sun is larger than 90% of the stars in our local section of the Milky Way, and lies about midway in size between the smallest and largest stars.

[Chris Peterson]

The video gives the impression that the Sun is a small star. This is not so. The Sun is larger than 90% of the stars in our local section of the Milky Way, and lies about midway in size between the smallest and largest stars.

No, the Sun is a small star. The smallest are around 10% its size; the largest are more than 1000 times larger. This video only looks at the absolute size range, not the size distribution. Of course, there are many more small stars, but that's not the point.

[bystander]

Am I the only one to recognize that the moon was rotating?? The moon does not rotate on its axis. We are presented with the same face of the moon at all times. Hence the saying..."Dark Side of the Moon"

The "far side of the Moon" (the side not facing Earth) is not the "dark side of the Moon". The side not facing the Sun is always changing. That is why we get Lunar phases.

[neufer]

Am I the only one to recognize that the moon was rotating?? The moon does not rotate on its axis. We are presented with the same face of the moon at all times. Hence the saying..."Dark Side of the Moon"

The "far side of the Moon" (the side not facing Earth) is not the "dark side of the Moon". The side not facing the Sun is always changing. That is why we get Lunar phases.

<<The dark side of the Moon can refer to the far side of the Moon that is permanently turned away from the Earth (although it receives approximately the same amount of light as the near side of the moon)>>

Dark, a. [OE. dark, derk, deork, AS. dearc, deorc; cf. Gael. & Ir. dorch, dorcha, dark, black, dusky.]

1. Destitute, or partially destitute, of light; not receiving, reflecting, or radiating light; wholly or partially black, or of some deep shade of color; not light-colored; as, a dark room; a dark day; dark cloth; dark paint; a dark complexion.

2. Not clear to the understanding; not easily through; obscure; mysterious; hidden.
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• • Love's Labour's Lost Act 5, Scene 2
  ROSALINE: What's your dark meaning, mouse, of this light word?
  
  KATHARINE: A light condition in a beauty dark.
  
  ROSALINE: We need more light to find your meaning out.
  
  KATHARINE: You'll mar the light by taking it in snuff;
  Therefore I'll darkly end the argument.
  
  ROSALINE: Look what you do, you do it still i' the dark.
  
  KATHARINE: So do not you, for you are a light wench.
  
  ROSALINE: Indeed I weigh not you, and therefore light.

[JohnD]

Am I the only one to recognize that the moon was rotating?? The moon does not rotate on its axis. We are presented with the same face of the moon at all times. Hence the saying..."Dark Side of the Moon"

I was wrong about the Black Hole, but I'm sure I'm right about the Moon!
The Moon does rotate, it turns to keep the same face towards the Earth at all times, save for a little libration.
Its rotation is "tidally locked" to its orbit.

A demonstration. This won't work if you hold the apple yourself, Midday, but have someone hold an apple (or a football!!!) and walk around you, without turning, keeping their face towards one direction all the time. You will see all sides of them and the apple. Only if you allow them to turn as they move can the keep their face towrads you and hide the far side of the apple.


Oops, now I see that ro-star got there first. Never mind.
John

[Rusty Brown]

Planets and Sun are rotating in reverse.

Either that or they're upside down

They're not upside down. Look at Earth, for example. The continents are in their customary orientation. Somebody dropped the rocky and watery ball big time on this one.
RB in Canada

[Planetarian]

Venus is spinning correctly I believe

[neufer]

Venus is spinning correctly I believe

Yes...but backward spinning planets with provocative nomenclatures should have been excluded from the line-up in favor of their prettier blue twins with larger orbits (and large moons). (Which is basically why Uranus was excluded.)

[Beyond]

Uranus is sort of on the backside of the solar system, isn't it

[rochelimit]

Inaccuracies:

Venus's atmosphere should be included!
Rotation! like clockwise Venus, but that doesn't really matter
Saturn's bulge should be squat, ellipse like, instead of a perfect sphere
Why forget Uranus? but that doesn't really matter

[Chris Peterson]

Inaccuracies:

Venus's atmosphere should be included!
Rotation! like clockwise Venus, but that doesn't really matter
Saturn's bulge should be squat, ellipse like, instead of a perfect sphere
Why forget Uranus? but that doesn't really matter

To bad, however, that you entirely missed the point of the video! Ever heard the one about the forest and the trees?

[neufer]

Inaccuracies:

Venus's atmosphere should be included!
Rotation! like clockwise Venus, but that doesn't really matter
Saturn's bulge should be squat, ellipse like, instead of a perfect sphere
Why forget Uranus? but that doesn't really matter

To bad, however, that you entirely missed the point of the video! Ever heard the one about the forest and the trees?

• Nevertheless, the APOD was asking for "inaccuracies" (if not "inconsistencies"):

Explanation: ... Although an inspiring learning tool that is mostly accurate, APOD readers are encouraged to complete the learning experience -- and possibly help make future versions more accurate -- by pointing out slight inaccuracies in the video.

[mttopman]

isn't "no, you are not the center of the universe" a double negative? So we are the center after all. Go figure

[Chris Peterson]

isn't "no, you are not the center of the universe" a double negative? So we are the center after all. Go figure :)

No, "no, you are not the center of the universe" is not a double negative.

And indeed, we are at the center of the Universe, both geometrically and in terms of expansion. But we are not at the center figuratively, in the sense of our importance (except to ourselves). And it's pretty clear the author was using that latter sense.

[bystander]

isn't "no, you are not the center of the universe" a double negative?

I guess it would depend on what the original question was. If the original question was "Am I the center of the Universe?", then the answer to your question is "Yes, it isn't a double negative." On the other hand, if the original question was "Am I not the center of the Universe?", then your answer would be "No, it is a double negative." But in that case the correct response to the original question would have been "Yes, you are not the center of the universe."

[Anthony Barreiro]

Am I the only one to recognize that the moon was rotating?? The moon does not rotate on its axis. We are presented with the same face of the moon at all times. Hence the saying..."Dark Side of the Moon"

The Moon rotates once each month. http://curious.astro.cornell.edu/questi ... number=142

[Awda]

Excellent video to get people thinking. But if we want to engage the public into looking up and wondering about where we are and how we fit in, we'll have to do away with posts from the likes of "Bergerac". It's that kind of quasi-academic piffle that will stifle today's students from becoming tomorrow's visionaries.

[soad22]

There is an inaccuracy near the end of the movie: I am indeed the center of the universe.

Center of your observable universe

[DougHuggem]

Hugo,
By definition, a Black Hole has no size. It is a point in space with no diameter at all.
Perhaps a BH should be the focus of a similar size comparison video going smaller rather than larger.
This video ends at the Plank length - a BH should be smaller than that!
https://www.youtube.com/watch?v=MKtfBd8QnYE

John

I would assume it was intended that the black hole's event horizon diameter be used as the basis for comparison

[felixfelixby]

diametr, km 2 800 000 000
circle lenth, formula diam.*3,14159
distance, km 8 796 452 000
hours in a day 24
velocity 900
distane per day, km 21 600
days in a year 365
distane per year, km 7 884 000
trip duration, years 1 116

[neufer]

diametr, km 2 800 000 000
circle lenth, formula diam.*3,14159
distance, km 8 796 452 000
hours in a day 24
velocity 900
distane per day, km 21 600
days in a year 365
distane per year, km 7 884 000
trip duration, years 1 116

That's only if there are no flight delays.

[Chris Peterson]

There is an inaccuracy near the end of the movie: I am indeed the center of the universe.

Center of your observable universe :wink:

No, physically at the geometric center of the entire Universe. That is almost certainly accurate for every 3D point in the spatial universe.

[neufer]

There is an inaccuracy near the end of the movie: I am indeed the center of the universe.

Center of your observable universe

No, physically at the geometric center of the entire Universe. That is almost certainly accurate for every 3D point in the spatial universe.

But, in the case of the entire Universe the term "center" has no meaning.

Whereas, the center of yannick's universe does have a meaning.

(Say "the center of yannick's universe" five times fast.)