Starship Asterisk*

http://en.wikipedia.org/wiki/Triangulum wrote:

Future precessional movement

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Triangulum + γ = the constellation known as [sup]MUL[/sup]APIN

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<<In the Babylonian star catalogues, Triangulum together with γ And formed the constellation known as ^MULAPIN "The Plough". It is notable as the first constellation listed in the pair of tablets containing the canonical star lists compiled around 1000 BC, which are thus known as the MUL.APIN by their incipit. The Plough was the first constellation of the "Way of Enlil", i.e. northernmost quarter of the Sun's path [containing 33 stars or constellations], corresponding to the 45 days on either side of summer solstice.

An early name of the constellation was Sicilia, because Ceres, patron goddess of Sicily, was claimed to have begged Jupiter that the island be placed in the heavens.>>

http://en.wikipedia.org/wiki/MUL.APIN wrote:
<<MUL.APIN is the conventional title given to a Babylonian compendium that deals with many diverse aspects of Babylonian astrology. It is in the tradition of earlier star catalogues, the so-called Three Stars Each lists, but represents an expanded version based on more accurate observation, likely compiled around 1000 BC. The text lists the names of 66 stars and constellations and further gives a number of indications, such as rising, setting and culmination dates, that help to map out the basic structure of the Babylonian star map.

The catalogue is the direct predecessor of the classical Neo-Babylonian zodiac as it was developed in the 7th century BC, which was in turn received by Eudoxus of Cnidus in the 4th century, giving rise to Hellenistic astrology.

The text is preserved in a 7th century BC copy on a pair of tablets, named for their incipit, corresponding to the first constellation of the year, MULAPIN "The Plough", identified with Triangulum plus Gamma Andromedae. The latest copies of Mul-Apin are currently dated to around 300 BC.

Astrophysicist Bradley Schaefer claims that the observations reported in these tablets were made in the region of Assur at around the year 1370 BC.

The text runs to two tablets and possibly a third auxiliary tablet. The first tablet is the most important resource for any potential reconstruction of the Babylonian star map as its various sections locate the constellations in relation to each other and to the calendar. Tablet 1 has six main sections:

• * All the major stars and constellations are listed and organised into three broad divisions according to celestial latitude allocating each star to three paths:
  • o the northern path of Enlil containing 33 stars or constellations
    o the presumably equatorial path of Anu containing 23 stars or constellations, and
    o the southern path of Ea containing 15 stars or constellations,
    Most of these stars and constellations are further attributed to a variety of Near Eastern deities.
  * The heliacal rising dates of 34 stars and constellations are given according to the 360-day ‘ideal’ calendar year.
  * Lists of stars and constellations that rise and set at the same time.
  * The number of days between the risings of various stars and constellations.
  * The stars and constellations that rise and culminate at the same time.
  * The stars on the path of the moon, being the major constellations close to the ecliptic, which includes all the Babylonian forerunners to the zodiac constellations.

Even though the Babylonians used a luni-solar calendar, which added an occasional thirteenth month to the calendar, Mul-Apin, like most texts of Babylonian astrology, uses an ‘ideal’ year composed of 12 ‘ideal’ months each of which was composed of an ‘ideal’ 30 days. In this scheme the equinoxes were set on the 15th day of the first and seventh month, and the solstices on the 15th day of the fourth and tenth month.>>

Magellan Starswarm wrote:
Do all galaxies spin in the same direction as the great spiral egg we call the Milky Way?

Patiently waiting Yogi wrote:Spiral arms are essentially fixed standing waves and stars orbit into the concave side of these arms and come out the convex side of these arms.

owlice wrote:

Patiently waiting Yogi wrote:Spiral arms are essentially fixed standing waves and stars orbit into the concave side of these arms and come out the convex side of these arms.

So the arms aren't rotating, the galaxy as a whole doesn't rotate? Stars pass through them as they rotate around the galactic center; the composition of the arms change as stars move through them, is that right?

Chappy wrote:
From what I understand, and it is limited, Galaxies do rotate, but unlike how you would think. Since the laws of physics state that a spinning object rotates faster the closer you get to it's rotational center, you would expect Galaxies to basically spin themselves to pieces since they are not a solid piece of matter, and the outer arms would lag so far behind that it would be a jumbled mess in no time....but they don't.

They spin at almost exactly the same rate at the center as they do at the edge, meaning that something is basically holding it all together as one solid kinda piece.

http://en.wikipedia.org/wiki/Spiral_galaxy wrote:

Explanation of spiral galaxy arms made up of elliptical orbits.

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The first acceptable theory for the spiral structure
was devised by C. C. Lin and Frank Shu in 1964.

* They suggested that the spiral arms were manifestations of spiral density waves.

* They assumed that the stars travel in slightly elliptical orbits and that the orientations of their orbits is correlated i.e. the ellipses vary in their orientation (one to another) in a smooth way with increasing distance from the galactic centre. This is illustrated in the diagram. It is clear that the elliptical orbits come close together in certain areas to give the effect of arms. Stars therefore do not remain forever in the position that we now see them in, but pass through the arms as they travel in their orbits.

Chappy wrote:They spin at almost exactly the same rate at the center as they do at the edge, meaning that something is basically holding it all together as one solid kinda piece.
The leading hypothesis of course, is that space & time constitute a fabric like substance due to dark matter/energy, and because of being suspended, so to speak, in this fabric, the entire Galaxy spins as a single object while individual objects within the galaxies are doing there own thing...kinda...in a way...sorta.

The explanation involves the presence of a large amount of dark matter, which is like any other matter in terms of its gravitational effects, but doesn't interact with electromagnetic radiation, so is essentially invisible to us.

Alignment of spin axis with cosmic voids
Recent results suggest that the orientation of the spin axis of spiral galaxies is not a chance result, but instead they are preferentially aligned along the surface of cosmic voids. That is, spiral galaxies tend to be oriented at a high angle of inclination relative to the large-scale structure of the surroundings. They have been described as lining up like "beads on a string," with their axis of rotation following the filaments around the edges of the voids.

Don Lund wrote:Umm, OK. But if DM behaves like any other matter in terms of its gravitational effects, why doesn't it orbit the galactic center faster near the center than it does much further out? My idiot impression is that DM is sort of gluing the galaxy together so that it rotates in a semi-rigid way, and somehow that just doesn't seem to make sense...

nstahl wrote:
Thank you neufer. That's fascinating.

It explains how density waves could occur but brings up questions of how such correlated orbits came about.

Chris Peterson wrote:

Don Lund wrote:Umm, OK. But if DM behaves like any other matter in terms of its gravitational effects, why doesn't it orbit the galactic center faster near the center than it does much further out? My idiot impression is that DM is sort of gluing the galaxy together so that it rotates in a semi-rigid way, and somehow that just doesn't seem to make sense...

It is orbiting faster near the center. The dark matter halo is a lot larger, and a lot more massive, than the ordinary matter. So the entire gravitational environment around a galaxy is altered by its presence. In particular, the DM halo is spherical, and for any visible component of the galaxy, most of the mass will be outside its orbital radius.

The dark matter isn't strictly gluing anything together, although the analogy isn't too bad. And a galaxy doesn't rotate as if it were rigid- the inner stars orbit faster than the outer ones. It's just that the difference in rotational velocity is smaller than can be explained if the visible mass is all there is.

owlice wrote:Thanks, Yogi!

beyond wrote:
Baseball had it's Yogi Berra - and now i see Apod has a Yogi we have to beara.
Lets hope he doesn't 'strike-out' toooo much

http://www.brainyquote.com/quotes/authors/y/yogi_berra.html wrote:

Yogi Berra quotes:

A nickel ain't worth a dime anymore.

All pitchers are liars or crybabies.

Always go to other people's funerals, otherwise they won't come to yours.

Baseball is ninety percent mental and the other half is physical.

Congratulations. I knew the record would stand until it was broken.

Even Napoleon had his Watergate.

Half the lies they tell about me aren't true.

He hits from both sides of the plate. He's amphibious.

How can you think and hit at the same time?

I always thought that record would stand until it was broken.

I just want to thank everyone who made this day necessary.

I never blame myself when I'm not hitting. I just blame the bat and if it keeps up, I change bats.
After all, if I know it isn't my fault that I'm not hitting, how can I get mad at myself?

I never said most of the things I said.

I think Little League is wonderful. It keeps the kids out of the house.

I wish I had an answer to that because I'm tired of answering that question.

I'm a lucky guy and I'm happy to be with the Yankees. And I want to thank everyone for making this night necessary.

I'm not going to buy my kids an encyclopedia. Let them walk to school like I did.

If people don't want to come out to the ball park, nobody's gonna stop 'em.

If the world was perfect, it wouldn't be.

If you ask me anything I don't know, I'm not going to answer.

If you come to a fork in the road, take it.

If you don't know where you are going, you might wind up someplace else.

In baseball, you don't know nothing.

In theory there is no difference between theory and practice. In practice there is.

It ain't over till it's over.

It ain't the heat, it's the humility.

It gets late early out there.

It was impossible to get a conversation going, everybody was talking too much.

It's like deja-vu, all over again.

It's pretty far, but it doesn't seem like it.

Little League baseball is a very good thing because it keeps the parents off the streets.

Nobody goes there anymore. It's too crowded.

Slump? I ain't in no slump... I just ain't hitting.

So I'm ugly. So what? I never saw anyone hit with his face.

The future ain't what it used to be.

The other teams could make trouble for us if they win.

The towels were so thick there I could hardly close my suitcase.

There are some people who, if they don't already know, you can't tell 'em.

We have deep depth.

We made too many wrong mistakes.

When you arrive at a fork in the road, take it.

You better cut the pizza in four pieces because I'm not hungry enough to eat six.

You can observe a lot by just watching.

You should always go to other people's funerals, otherwise, they won't come to yours.

You wouldn't have won if we'd beaten you.

You've got to be very careful if you don't know where you are going, because you might not get there.

neufer wrote:

http://www.brainyquote.com/quotes/authors/y/yogi_berra.html wrote:

Yogi Berra quotes: