Comments on: David or Goliath?

By: Magnum

Magnum — Fri, 09 Mar 2007 18:54:07 +0000

I’m surprised that astronomers are still fumbling around in the dark so much that they can’t tell if a galaxy is 13 million or 150 million light years away. But after reading the linked article I see it was (presumably) quite easy to determine the distances by observing the red-shifts, and there was also some good information about chemical composition (from spectography I guess). So much to learn!

By: Mark Martin

Mark Martin — Fri, 09 Mar 2007 11:27:03 +0000

Our galaxy never got a population boom. It’s still estimated to be in the neighborhood of between 100 & 200 billion stars. The “trillion” figure was just someone’s mistake.

By: Angelo

Angelo — Fri, 09 Mar 2007 08:42:56 +0000

Gary took my question, when did our galaxy increase from approx. 1 billion stars to trilllions of stars? I think what is meant is the whole shebang is trillions of stars and more. And I also agree with Din, We ‘adapted ‘to our part of the universe, not vice versa which makes it look as if the universe was made for us.

By: Walabio

Walabio — Fri, 09 Mar 2007 06:38:18 +0000

Gary 7:

> Gary Ansorge Says:

>> So, when did the Milky Way get boosted from 100 billion or so stars to 1 trillion? I guess I missed that?

> Gary 7

They did not. The Milky Way has about four hundred billion stars. The total stellar mas in the Milky Way is about an hundred billion solar masses (most stars are less massive than the sun. The total baryonic mass of the Milky Way is about two hundred billion solar masses. About three fourths of the milky Way is nonbaryonic mass (dark matter).

Scientists hypothosize that the dark matter is neutrinoes, but no-one knows for sure. If you believe that dark matter is strange, than you should check out dark energy:

* – http://wikipedia.org/wiki/dark_matter

* – http://wikipedia.org/wiki/dark_energy

By: Gary Ansorge

Gary Ansorge — Thu, 08 Mar 2007 14:58:24 +0000

Saw the big dipper last night. Clear skiis and low light polution are more common where I live now than they were in Los Angeles.

So, when did the Milky Way get boosted from 100 billion or so stars to 1 trillion? I guess I missed that?

Gary 7

By: Mark Martin

Mark Martin — Thu, 08 Mar 2007 11:22:12 +0000

The 8th one up is “Find the Big Dipper”. Quite a feat.

By: bassmanpete

bassmanpete — Thu, 08 Mar 2007 08:28:22 +0000

So what is the 8th from bottom of the List of things to do while you’re alive? The list of things to do after is probably quite short, I imagine

By: din

din — Thu, 08 Mar 2007 06:00:17 +0000

“Another reminder that the universe is not made to suit us; we developed to suit the particular conditions of our little corner of the universe.”

Or its just another reason why god made the universe just right for us. Long may the squid rule !

its the sky being blue that interests me … from memory of Phil’s book, it wouldn’t be blue if things where slightly different, ie black if we looked up at the moon, and its red when we look at sunset.

By: JanieBelle

JanieBelle — Thu, 08 Mar 2007 02:00:41 +0000

Well now you went and made me look it up. Bugger.

The diameter of the sun is 1.4 million km, the moon about 3500 km and that does indeed work out to about 400X.

Now I know something I didn’t know yesterday.

By: Crux Australis

Crux Australis — Thu, 08 Mar 2007 01:43:09 +0000

If the Sun has 400 times the diameter (and therefore radius) then it must have 400^3 or 64 million times the volume.

By: Crux Australis

Crux Australis — Thu, 08 Mar 2007 01:41:28 +0000

750 billion solar masses? That’s big. So what’s the latest count of stars in the MW?

By: Ian Menzies

Ian Menzies — Thu, 08 Mar 2007 01:39:24 +0000

“Itâ€™s not luck, itâ€™s simple coincidece.”

I would say that luck is coincidence.

By: JanieBelle

JanieBelle — Thu, 08 Mar 2007 01:39:19 +0000

The Sun is 400 times the physical size of the Moon,

We’re talking diameter, right? I mean it has to be a way bigger difference in terms of volume, right?

By: wright

wright — Thu, 08 Mar 2007 01:22:45 +0000

I love it:

“We’re basically in the middle of a long eclipse season.”

A great way of putting it, Phil. Another reminder that the universe is not made to suit us; we developed to suit the particular conditions of our little corner of the universe.

By: The Bad Astronomer

The Bad Astronomer — Thu, 08 Mar 2007 00:59:21 +0000

It’s not luck, it’s simple coincidece. A billion years ago the Moon was so close it covered up way more than the Sun, and a billion years from now it’ll have moved far enough away that we’ll never get total eclipses any more. We’re basically in the middle of a long eclipse season.

By: Mark Martin

Mark Martin — Thu, 08 Mar 2007 00:58:47 +0000

Hey, sorry to get off-topic, but check out the full-page ad on the back cover of this week’s Newsweek. It has a list of “Things to do while you’re alive”. Check out the 8th one from the bottom. It’s not exactly bad astronomy, but including it in a list of things to accomplish (for those in the Northern Hemisphere) surely is symptomatic of a bad astronomy culture.

By: Porto

Porto — Thu, 08 Mar 2007 00:17:56 +0000

” Itâ€™s a bit like the Moon and Sun in the sky: The Sun is 400 times the physical size of the Moon, but itâ€™s also 400 times farther away, making them both about the same apparent size to the eye.”

Of all the cosmics coincidences, thats is my favorite for sure. We are very luck to be on a planet that can witness a eclipse that matches the size of moon and the sun.

By: blizno

blizno — Thu, 08 Mar 2007 00:17:55 +0000

I wonder how many old misinterpretations there are in the literature and how many of them will stay that way because there’s so much else to look at.

By: bswift

bswift — Wed, 07 Mar 2007 23:52:30 +0000

The astronomers took spectra of the two which turned out to have very different redshifts. According to the linked article “coordinate confusion and wrong distance estimates in the literature for the last 23 years.”

Doesn’t seem like it was that big of a controversy — someone just finally got around to getting spectra again.

By: kingnor

kingnor — Wed, 07 Mar 2007 23:22:10 +0000

so i’m sure this concept isn’t new to astronomers, i’m guessing they were thinking: “its either BIG and just as far away, or its small and realy close. or maybe its REALLY REALLY BIG and even farther away”

What exactly happend that allowed them to narrow down the size?

By: blizno

blizno — Wed, 07 Mar 2007 22:49:13 +0000

I thought the Milky Way was an average galaxy. The first Google hit tells me it probably contains between 750 billion and a trillion solar masses and is indeed a giant galaxy.
http://www.seds.org/messier/more/mw.html
I was taught that we’re on an average planet orbiting an average star which is part of an average galaxy (admitted, grade school science was a long time ago for me). We’re part of a giant galaxy! Yay, us!

I’m a little surprised by the picture. The lower “smear” looks like it has a hard, bright center and a diffuse outer region. My inexperienced eye would have guessed it be much smaller and much closer than the well-formed disk galaxy above it.