One thing I can’t reconcile is the size of the universe versus its age. If /c/ is the universal speed limit (and we know it’s a constant) and the age of the universe is 13.6 billion years, I don’t get how the universe can be larger than 27.2 billion light years across the widest point.

So far most of what I’ve read has used analogies similar to compound interest, but — at least in these explanations — it seems to imply a changing /c/, something that can’t happen without drastically distorting all the other numbers.

Care to give this one a shot? I’ll try to be on-line for the live show.

I found this on a Nasa page:

“However, at the point in the night sky opposite of where the Sun is on the daylight portion of the Earth (antisolar point), the feeble band brightens slightly. It’s not all that obvious, but nonetheless it’s pretty impressive to think that in the middle of the night, a spot of light opposite the Sun can be detected with the unaided eye. This oval-shaped spot is known as the gegenshein or the counterglow and the time to look for it is around midnight (in February and March and again in October and November). The myriad dust grains along the ecliptic, when they’re opposite the Sun, act like little moons that reflect light back toward the Earth. Even though it’s very faint, the gegenschein is surprisingly big, about the size of your fist held at arm’s length, and it’s not a stationary feature – it migrates across the night sky during the course of several months.”

This is the exact phenomenon that was photographed.

Then it’s only new for me

Going through the archives to find my Omega Cen questions sure takes a while .. These were asked on 11th April – & on the 5th too. Still now at last I’ve found them – once & still unanswered here :

http://www.badastronomy.com/bablog/2008/04/10/spitzer-bags-omega-cen/

(Hope my netiquette is ok – apologies if not.)

Not meaning to hog this thread (& yeah I wouldn’t mind hearing about Wolf-Rayet stars & other stuff too) but I’ve tried three times now toget answers to these & I don’t think that that bad questions so please BA can I have answers to these somewhere .. even just quickly here?

Fascinating news about Omega Centauri – some implications and questions I’ve got are :

1) If Omega Centauri is reclassified as a dwarf galaxy does that make it the nearest dwarf elliptical or is the Sagittarius dwarf or another of those captured shredded dwarfs actually closer?

2) If it is a galaxy won’t it join the list of just a handful of galaxies visible to the unaided eye – the two Magellanic Clouds, Andromeda, Triangulum – M33, & now the Omega Centauri dwarf galaxy? Has the Local Group of galaxies gained a new member and, if so, where does Omega Cen sit in the hierarchy – would it be the smallest dwarf or is it larger than some of the other very faint dwarfs?

3) Can Omega be considered as being *both* a galaxy and a globular cluster (like eg. Ceres = largest asteroid & dwarf planet) or would we it be better to say instead that it used to be an independent galaxy but has since been transformed via capture (?) into a globular cluster? Can a galaxy be part of another galaxy and how long should it be before a smaller galaxy is considered fused into or a component part of a larger galaxy?

4) To be a galaxy does Omega need to boast globular clusters of its own? Does it have – or are there any signs it might have had – its own orbiting globulars or extended stellar halo or even dark matter halo?

Which leads on to the question of :

Should the IAU be trusted to define what a galaxy is after their botch-up with Pluto!

5) Is it the only object like this or could there be more – both around our galaxy and inside others? What are the implications for other globulars and their evolution? Could there be two separate populations or types of globulars – those that used to be separate galaxies and those that were always part of their primary galaxy?

Third time lucky for getting a response here?
Has my persistence paid off at last?

Or have I missed some answers there already? Sorry if so …

Anyhow thanks again, kind Bad Astronomer , for giving me the opportunity to ask & hopefully I’ve given you enough & not more than enough questions to work on!
———————
PS. Another suggestion for your suggestion box : Please could we have the archives in some sort of just “by title – then link” style listing format to make a whole lot easier to find? A constructive suggestion, I hope.
PPS. All this time & no other posters? Hmm .. must be late night / early morn over in the Us of A! (As well as here in Oz now!)

Sorry … Take II :
________________________________________

How about these questions which I asked on the meteor___
censored thread :

… that source asteroid is Pallas – one of the larger & first discovered main belt asteroids I’m guessing – hence the name?

Plus also, is the asteroid belt (well both asteroid belts really) getting noticeably smaller over the millennia along with the size of the largest objects in it as impacts erode down the size & mass of the largest objects? ….

Or the whole heap of questions I asked about the Omega Centauri =elliptical galaxy? thing? They’re all on that thread if you want to check them out & haven’t answered already ..

Or & here’s a new one or three (I think!) :

1) Is it possible for the Earth-Moon system to capture a comet in orbit about it the way Jupiter did Shoemaker-Levy 9 & if so what would it look it & could it last & become a second moon?

2) How different (temp. /climate~wise?) would our planet be if the Sun was just one spectral class different ie. a G1 or G3 star? How about two types different eg,. G0 or G4 or a full spectral class eg. a K2 or F2 star?

&

3) If our Sun had a Hot Jupiter (or Hot Neptune or Super-Earth?) type planet orbiting it in about every 2 days or every 7 days then how would it appear in our skies? Would we see it & could we tell it was there?

There’s a few thoughts for ya anyway!

(Hope the HTML (?) tags have worked this time around … )