Astrophysics and Cosmology - Discuss the Universe here

[Unquenchable Angst]

https://en.wikipedia.org/wiki/Jack_Horkheimer

Dead 2010

[Agent : Orange]

I've never heard of Horkheimer before. I'm sure there are some clips on youtube

[Mind Flayer Monk]

BTW, anyone remember Jack Horkheimer (what a name!), AKA, Stargazer?  Is he still alive?

I've never heard of Horkheimer before. I'm sure there are some clips on youtube

I remember him. He used to have a 5 minute show on PBS, and it was always the last show of the evening before PBS went off air.
Because of its positioning, it was perfect for night owls. It would come on after shows like Dr Who, Fawlty Towers, or Monty Python (all usually aired in the final evening slot at PBS). Also, it was the beginning of the era of the VCR, so many people taping Monty Python or Dr Who would have the last five minutes of the tape with "the Stargazer". The Stargazer often filled up the 11:55-12:00 part of the timer.


http://youtu.be/igHOaMOzzUo

[zeebo]

I remember him. He used to have a 5 minute show on PBS, and it was always the last show of the evening before PBS went off air.
Because of its positioning, it was perfect for night owls. It would come on after shows like Dr Who, Fawlty Towers, or Monty Python (all usually aired in the final evening slot at PBS). Also, it was the beginning of the era of the VCR, so many people taping Monty Python or Dr Who would have the last five minutes of the tape with "the Stargazer". The Stargazer often filled up the 11:55-12:00 part of the timer.

Yep always loved catching those after a late nite Python/Who episode.  He was a character and I loved his catch-phrase "Keep Looking Up".  Btw, before he was the Stargazer, he was "the Star Hustler" ...


https://www.youtube.com/watch?v=LkJheh1XcAQ

[zeebo]

A:O, what gear setup do you recommend for casual stargazers? Do you use a home setup at all?

I think a reflector with around 4.5-6 in. mirror is a pretty good place to start.  I have a 135mm (5.3 in.) and it's been nice.  It's a little bulky but can def. pick up more stuff than those little 70mm tubes and is still relatively portable.

The one thing I'd like to add is one of those automatic compensators for the earth's rotation.  Very annoying to get targeted into something with high magnification and then watch it zoom right out of view.

Btw this link has some decent info:  telescope buying guide

[onan]

I've never heard of Horkheimer before. I'm sure there are some clips on youtube

https://www.youtube.com/watch?v=LkJheh1XcAQ

[Mind Flayer Monk]

https://www.youtube.com/watch?v=LkJheh1XcAQ

That video is a good representation of him, his presentation, and cheezeball humor.
"..and another planet that is easy to identify in the daytime-excluding this one we are standing on, which I daresay most anyone should be able to find..."

[Tarbaby]

Just finished reading the thread. What a ride. Applause.

[maureen]

Just finished reading the thread. What a ride. Applause.

Indeed!! Thanks to all for these brilliant postings!

[Tarbaby]

For about four days now I can't stop thinking of the M87 Virgo cluster. The size, the distances involved. Several trillion stars, was it?

[zeebo]

For about four days now I can't stop thinking of the M87 Virgo cluster. The size, the distances involved. Several trillion stars, was it?

Yes, my favorite object in the sky!  It is mind-boggling for sure.  Whereas I've seen estimates for number of stars in the Milky Way at between 100-400 billion, I've seen estimates for M87 of 2-3 trillion solar masses - but I'm not sure exactly what that means.  Perhaps Agent Orange can give a more precise definition.

I did see somewhere that just the stars that make up it's 12000 globular clusters (compared to the Milky Way's 200 or so) probably add up to around a trillion stars.

Definitely there's alot more stars in there for sure as it has a wider diameter of the Milky Way but is not a flat spiral, but rather it's spherical so it has a much bigger volume.  I read somewhere that in the past it may have merged with 100 or so smaller galaxies to get it's immense mass and the monster black hole at it's center.

M87 is one of the main centers of gravity in the Virgo cluster of around 1300 galaxies. 

[zeebo]

I did see somewhere that just the stars that make up it's 12000 globular clusters (compared to the Milky Way's 200 or so) probably add up to around a trillion stars.

Sorry: I think the math was wrong where I got that stat from.  Apparently globular clusters can range from thousands to upwards of 10 million stars, with an average of maybe a hundred thousand ... so 12,000 x 100,000 = 1.2 billion not trillion (stars in globular clusters). 

However I've seen references that M87 as a whole does contain at least a trillion stars and that it's total mass is "many" times that of the Milky Way.

[Moonbog]

[area51drone]

WTF do I repeatedly like Vladimir Putin far better than our own president?

http://www.dailymail.co.uk/news/article-2602291/We-coming-Moon-FOREVER-Russia-sets-plans-conquer-colonise-space-including-permanent-manned-moon-base.html

[Tarbaby]

quote author=Moonbog link=topic=4908.msg249818#msg249818 date=1397274486]

[/quote]Zeebo, thanks for the extra information!

Agent orange: could you briefly describe The formation of the M87 cluster? I can't visualize howthe spiral action begins. Not to mention the incredible distance in the radius of that galaxy were gravity could still exert any influence. The only way I can visualize it is if I think of the analogy of space itself being curved by gravity. But apparently this model for the laws of attraction does not work with reference to dark matter.

[area51drone]

Agent orange: could you briefly describe The formation of the M87 cluster? I can't visualize howthe spiral action begins. Not to mention the incredible distance in the radius of that galaxy were gravity could still exert any influence. The only way I can visualize it is if I think of the analogy of space itself being curved by gravity. But apparently this model for the laws of attraction does not work with reference to dark matter.

Have you ever rolled two ball magnets near each other?    Think about how even an asteroid starts spinning.   It doesn't take much to get the ball rolling, so to speak.

[Agent : Orange]

Agent orange: could you briefly describe The formation of the M87 cluster? I can't visualize howthe spiral action begins. Not to mention the incredible distance in the radius of that galaxy were gravity could still exert any influence. The only way I can visualize it is if I think of the analogy of space itself being curved by gravity. But apparently this model for the laws of attraction does not work with reference to dark matter.

A51D gives a good analogy for how you can think about it. I would also say that another useful picture is that of an ice skater who starts spinning slowly at first with her arms extended outward. As she pulls her arms in she begins to spin faster. This is a demonstration of conservation of angular momentum, which also causes galaxies (and stars, and pretty much anything else formed by condensing from a big cloud of material) to spin perpendicular to the rotation axis. There is a lot of mass within the galaxy so it generates a huge gravitational attraction, even on stuff that's very far away.

I don't really understand what you mean by your last comment with respect to dark matter. Can you explain it a bit more?
Current thinking is that dark matter produces gravity just like any other type of mass, so it causes space-time to curve just like any other type of matter.

[Agent : Orange]

This is awesome.

[Tarbaby]

A51d and AO:
Oh, thanks, I didn't realize all planetary bodies were virtual giant magnets.

And my question about dark matter was since it has virtually no interaction with regular matter how could it still respond to gravity, as regular matter does? It's as if regular matter is not the primary  cause of gravity but rather a result of it.Because dark matter doesn't have a direct relationship to regular matter.

I'm thinking of the "bullet" cluster.

Years ago when I found out there are no Tiny particles of matter or Beebes in atoms, and only vibrational nodes of energy, I started thinking of apparent reality as a gigantic virtuall holograph. And recent focus of higher octave frequencies on strings being associated with dark matter seem to further suggest this.

[area51drone]

Years ago when I found out there are no Tiny particles of matter or Beebes in atoms, and only vibrational nodes of energy, I started thinking of apparent reality as a gigantic virtuall holograph. And recent focus of higher octave frequencies on strings being associated with dark matter seem to further suggest this.

This is an interesting thought.

[Tarbaby]

still, clearly, there is some kind of relationship. And I don't think it's two forms of the same thing. They are in the same vicinity but not the same place, often. I am going to have to retract my idea that matter is an effect rather than a cause of gravity. :-) I couldn't see how matter and dark matter could  be ghosts to each other yet both cause gravity. Yet it's puzzling how dark matter can cause gravity yet not attract normal matter. But I think I get it now, more or less. The puzzlement is due to the fundamental nature of dark matter and regular matter. The different string frequencies.

[Agent : Orange]

still, clearly, there is some kind of relationship. And I don't think it's two forms of the same thing. They are in the same vicinity but not the same place, often. I am going to have to retract my idea that matter is an effect rather than a cause of gravity. :-) I couldn't see how matter and dark matter could  be ghosts to each other yet both cause gravity. Yet it's puzzling how dark matter can cause gravity yet not attract normal matter. But I think I get it now, more or less. The puzzlement is due to the fundamental nature of dark matter and regular matter. The different string frequencies.

Dark matter causes gravity and this attracts all kinds (both normal and dark) matter. Dark matter is essential for building up the structures we see in the universe from galaxies and galaxy clusters. So it does interact with normal matter through it's gravity, which is just the curvature of space-time. All matter and energy reacts to this curvature.

[Agent : Orange]

A51d and AO:
Oh, thanks, I didn't realize all planetary bodies were virtual giant magnets.

They're not. But magnets rolling around on a table (Drone's example of how these things move around one another) made a decent example of circular motion in a plane. By no means do the magnetic fields of planets influence one another more strongly than their gravitational fields. I apologize for confusing this issue.

[Tarbaby]

They're not. But magnets rolling around on a table (Drone's example of how these things move around one another) made a decent example of circular motion in a plane. By no means do the magnetic fields of planets influence one another more strongly than their gravitational fields. I apologize for confusing this issue.

Oh. So then I'm back to my original question of what causes the spiral motion to begin. What causes the ice skater to start spinning. Why don't the clumps of matter that are attracted by gravity simply fall straight into the source of the gravity? In drones model I thought they were repelled by opposite magnetic forces while being attracted by gravity but now that cause of spiral action is ruled out.

And by the way, your explanation of dark matter and regular matter above
does that imply that there is probably dark matter at the center of every or many planets?

I hope you have enough patients for me to throw in another more esoteric question: we know that regular matter either produces or is influenced by life itself since we can move our bodies around and they're made of regular matter. So what do you think may be the relationship of life too dark matter? Dark matter neither reflects or creates or absorbs light. And it has no direct interaction with regular matter except gravitic as you say. So could there be entire planets composed of dark matter with my forms on their composed of dark matter?

[area51drone]

Oh. So then I'm back to my original question of what causes the spiral motion to begin. What causes the ice skater to start spinning. Why don't the clumps of matter that are attracted by gravity simply fall straight into the source of the gravity? In drones model I thought they were repelled by opposite magnetic forces while being attracted by gravity but now that cause of spiral action is ruled out.

Matter is attracted together by gravity, not repelled.    If two points (meaning like something smaller than a proton) of equal mass were sitting there all by themselves, still, then they'd fall directly at each other and maybe there would be no movement.    But, there is more than just two points, so you have interaction with a lot of different mass particles, molecules, rocks, etc.

Depending on their relative masses, as they hit each other, they collide and they will go in different directions.  Once in motion, they will  move *past* other lumps of mass, where gravity just tugs on them, causing them to spin around one another if there is enough force and correct particle velocity.   Assuming they start orbiting one another because their velocities are such to allow it,  eventually they spiral into each other and collide.   When they finally hit and stick together, the entire mass will be spinning.

Eventually there are enough collisions that the mass becomes bigger lumps, and new lumps coming in that do it also do not hit on center, causing more spin, etc etc.  Eventually it is all spinning, and it will spin faster as the mass gets crushed by gravity towards the center of rotation - just like Agent's figure skater tucking in her arms example.

[Tarbaby]

I didn't say matter was repelled by gravity, I said in your model of the magnets matter was repelled by magnetism.  which would easily explain a rotating movement beginning. agent orange has clarified that above. and to me your explanation of how the spiral begins his implausible. and by the way, do all galaxies been in clockwise or counterclockwise directions randomly? Or is the direction of spin somehow influenced by the curvature of the space time bubble?

And here's another thing: we exist on the surface of the space time continuum that was created by the Big Bang. So does a supermassive black hole tear through and rupture the surface of the continuum. And what's inside the bubble?

[area51drone]

and to me your explanation of how the spiral begins his implausible.

Why?

[Tarbaby]

There is another model that could explain the spiral effect. The same principles that cause water to spiral as it goes down the drain.

Next: how do we resolve the following two sentences, one, "matter and energy can be neither created nor destroyed", two, "matter and energy were  formed at the time of the Big Bang".

And thank you both for your civility and patience with me.

[zeebo]

For those who missed it, Keppler mission found an Earth-sized exoplanet in the habitable zone.  Who wants to go on a field trip!

http://www.cbc.ca/news/technology/earth-sized-planet-found-in-star-s-habitable-zone-1.2613794

[area51drone]

I've not watched it yet, but I just noticed today that Netflix added (or has) Neil Degrasse Tyson's The Great Courses seminars "The Inexplicable Universe".    I hope they add more great courses titles, the ones I have watched so far are all worth watching.