Viewing the night sky from the surface of earth

Jonnyboy · Post #1by **Jonnyboy** » 19.04.2007, 10:32

Hello all,

Just found Celestia today and it looks amazing, just the thing I have been looking for.

Now one of the things I would like to do is use it to help find objects in the night sky, i.e. sit virtually at my location on earth and look up to the stars so that I can locate certain objects and then go outside and literally find them. A star chart basically. Is this possible?

I try going to location and enter my lat. and long. coordinates but have difficulty viewing it in such a way that I am standing on the surface looking up.

I ran the script for az/el which works nicely in conjunctur with the star finding, but it seems to be loosing its position as to where i am viewing from.

Basically how do i securely plant my "feet" on my home location and look around, getting a view of the night sky that I should be able to go outside and see for real?

Hope this is an easy question and someone can help.

Regards,

Jon Reynolds

Cham · Post #2by **Cham** » 19.04.2007, 10:36

Celestia sucks at this. Just download Stellarium. It's free too, and much nicer than Celestia.

Post #3by **selden** » 19.04.2007, 11:01

Jon,

You mentioned a script for az/el.
Did you try simply putting Celestia in az/el mode?

See the "Preliminary User's FAQ", near the top of the Users Forum, Q/A # 19

Jonnyboy · Post #4by **Jonnyboy** » 19.04.2007, 11:07

Hi,

Thanks for the replies, but for my use I think Stellarium solves all my problems.

Thanks!

Post #5by **ElChristou** » 19.04.2007, 11:52

You can use Vincent's Edu Tools (do a search on the forum), there is a cool option that will let you down feets on the ground in whatever point of any planet.

BTW, a few nights ago, comparing my night sky with Celestia one, I found the moon was really big in the sky, thing that wasn't true in Celestia; was just a tiny body amost difficul to find comparing to the presence (size/brightness) of the real body. To get an aproximation of the level of details visible at naked eyes, I had use the FOV between 2 and 3. The problem is that in that case I lose big part of the natural field of view... Anybody noticed that or am I saying a big nonsense?

Post #6by **selden** » 19.04.2007, 12:02

ElChristou,

The apparent large size of the Moon is a well known optical illusion.

This size issue in Celestia is discussed in the Prelliminary User's FAQ,
Q/A #7

Post #7by **ElChristou** » 19.04.2007, 12:17

selden wrote:ElChristou,

The apparent large size of the Moon is a well known optical illusion.

This size issue in Celestia is discussed in the Prelliminary User's FAQ,
Q/A #7

Ah ok, Tx; anyway, such illusion would be nice to see... (Celestia is not try to simulate the human vision?). On ground, a glare around the moon would be also welcome...

Hungry4info · Post #8by **Hungry4info** » 21.04.2007, 01:52

I would have to disagree. Since the moon doesn't really look bigger near the horizon, I don't believe it should in Celestia either. The thing about the moon being large is all in the mind, not the eye.

Post #9by **ElChristou** » 21.04.2007, 10:55

Hungry4info wrote:I would have to disagree. Since the moon doesn't really look bigger near the horizon, I don't believe it should in Celestia either. The thing about the moon being large is all in the mind, not the eye.

What's the difference? Do you mean you are able to control the optical illusion and see the moon small just like it is now in Celestia?

Post #10by **t00fri** » 21.04.2007, 11:07

ElChristou wrote:
Hungry4info wrote:I would have to disagree. Since the moon doesn't really look bigger near the horizon, I don't believe it should in Celestia either. The thing about the moon being large is all in the mind, not the eye.

What's the difference? Do you mean you are able to control the optical illusion and see the moon small just like it is now in Celestia?

It's not so easy to incorporate optical illusions into Celestia, though, even if we wanted to do this ;-)

. If you simply would increase the moon's size near the horizon, then e.g. Mercury or Venus transits would begin and end at the wrong times...etc.

Bye Fridger

Post #11by **ElChristou** » 21.04.2007, 13:43

t00fri wrote:It's not so easy to incorporate optical illusions into Celestia...

I can believe this, it's just I have those nights some enormous and beautifull moons over here and they equivalent within Celestia are so insignificant...

My idea is to recreate in 3D my house, garden and near vegetation (all in correct proportions and orientation of course), this to see if Celestia sky really match the reality (I'm pretty sure it will, but this will be cool to do). The annoying with the moon is that I will never see it near a tree for example as big as I can see it in reality.

Despite the technical challenge, it could be a very nice option for Celestia (having a setting to turn on/off the physiological size of the moon -> for those who don't like the idea) to make it one more step before all softs in this category...

bh · Post #12by bh » 21.04.2007, 15:01

I've been looking out of the bedroom window in the evenings lately to look at the moon and Venus. To get anywhere near the same effect with celestia I have to up the field of view and deselect the stars... comes pretty close with a bit of tweaking.

Vincent · Post #13by **Vincent** » 21.04.2007, 18:37

In Stellarium, you can set the moon scale in the configuration file. I have to say that it is really pleasant to watch the night sky in Stellarium with a moon scale set to 4.

t00fri wrote:If you simply would increase the moon's size near the horizon, then e.g. Mercury or Venus transits would begin and end at the wrong times...etc.

That's true, I hadn't thought about this issue. I'll check it out in Stellarium... :wink:

psCargile · Post #14by **psCargile** » 21.04.2007, 18:55

Just change the SMA and bring the Moon closer.

Vincent · Post #15by **Vincent** » 21.04.2007, 20:41

Chris,

Since we're talking about the moon as seen from Earth, I noticed that in OGL Vertex program/NVidia combiners render path and with star style set to scaled disks, the halo of the moon at the default FOV (Zoom = 1) is so strong that half moon can't be seen.

Here are some screenshots illustrating the problem [Click to enlarge]:

1- Zoom = 1 (default FOV) : Half Moon replaced by halo.

2- Zoom increased up to 1.72: Half Moon can be properly seen.

I'm pointing this out since default FOV (zoom = 1) should correspond to what we can see in reality with naked eyes.

Aliced1989 · Post #16by **Aliced1989** » 22.04.2007, 01:01

Cham wrote:Celestia sucks at this. Just download Stellarium. It's free too, and much nicer than Celestia.

I think so

Post #17by **ElChristou** » 22.04.2007, 20:14

about the moon illusion (not a scientific paper but seems no one really knows what happen):

http://www.lhup.edu/~dsimanek/3d/moonillu.htm

Post #18by **ElChristou** » 22.04.2007, 21:49

a better one?

http://facstaff.uww.edu/mccreadd/

psCargile · Post #19by **psCargile** » 23.04.2007, 01:30

Next time you are outside and the Moon is out, scale it with your out-stretched hand. I found that the Moon would fit inside my pinky fingernail! That's about a quarter of an inch.

Post #20by **ElChristou** » 23.04.2007, 20:11

Another simple thing to do is just to close one eye; one see the right size. Use both eyes and... big. Seems part of the illusion is due to binocular vision...