MICHAEL A.  For any people who have ever found that jumping around to different places in Google Earth was an addictive adventure, this is even better...  
(Version 1.5)

ENRICO NENCINI  Awesome software. AND free. Tested on PPC and Intel (leopard): works seamlessly.  
(Version 1.5)

JAZZJOHANNES  Brilliant, I love the complete StarTrek TNG add-on.  
(Version 1.5)

TICE  This app is great. I used it since the early days and it still gets me. Wonderful work. Only the navigation could be more intuitive (i.e. the arrows left and right could change the direction instead of turning and up and down shouldn't be opposite).

Anyway, thanks for this great piece of freeware! : )  
(Version 1.5)

VERSANICK  First, let me reccomend this to anyone with an interest in Astronomy, or who is taking in Astronomy-related class somewhere (I sure wish I had this years ago when I was taking Astronomy in college).

Now, an amazing 3-dimensional adventure through the solar system and much more. To this minute, I've been through mostly the entire Milky Way, and I don't even know how far this program maps. This is amazing.

Very easy to learn how to navigate around. Drag around with the mouse, or use your arrow keys, travel at 100 m/sec or 100 times the speed of light, or on the scale of astronomical units per second (1 AU is the distance from earth to sun)... impressive, easy to turn on/off labels of orbits, planets, constellations, and much more (all easy to find in Preferences). You can even see cities, mountains, and other things, all at the click of the mouse.

Great choices of rendering paths (for graphics) from Basic to OpenGL 2.0, and many things in between (which will work better with different video cards, old and new). It will even tell you (in most cases) if you cannot use the selected rendering option. There's something for anyone. Beautiful graphics. I suggest that you see for yourself. It's hard to describe the fact that I can see almost every detail of the moon, as deeply as I've ever studied its surface. Very, very impressive on my 19" monitor on my G5 tower.

There's even a 'Favorites' menu (akin to Bookmarks). Zoom from planet to start to constellation in seconds. There is so much you can do with this program. Or just leisurely show your friends what a cool program you found.

I highly suggest this for anyone _teaching_ astronomy as a professor or teacher. Chris Laurel, and anyone else involved in developing this deserves credit for the most impressive and comprehensive (yet simple in nature) space exploration app I've seen that is so easy to use, even a relative computer novice can tool around.

And free. Props. I honestly can't say anything negative. Congrats on an amazing app. I wish I found this a long time ago.  
(Version 1.4.1)

SELF-INFLICTED  Wow. Seriously... wow.

Space is big. No, bigger than you're thinking. Really, really, mind-bogglingly big. Wow.

Easy to get lost in, too -- in time as well as space. I've lost track of how many hours I've spent tonight cruising the cosmos.

This is really an amazing visualization tool. It's not as if I need it in my daily work, but I sure like having it to escape to.  
(Version 1.4.1)

APPLECRYPT MODS  incredible - i love this s/w!!!

thank you :)  
(Version 1.4.1)

ANONYMOUS  At least one fan hopes for an update with:

-toggle on/off full screen

-the tenth planet!

-solar system guide (wide view of orbits)

-satellite mission guides with links to nasa pics

Thank you for a brilliant program, Celestia is the bomb.  
(Version 1.3.2)

ANCIENTYGER  a pre-release of 1.4x it has some issues (i've not seen them...) but, seems to work well on a mini.

http://shatters.net/forum/viewtopic.php?t=7457

please, follow the forums and post there show your support for the mac version, but know that it is under development and hasn't been ignored.

This, is some great software!  
(Version 1.3.2)

ANONYMOUS  Celsetia worked fine on my G3 iBook when running 10.2. But on my G4 iBook running 10.3 it crashes the whole system.

And I did do everything the ReadMe file says.  
(Version 1.3.2)