Eclipse Shadows and red giants
Posted: 15.11.2004, 08:02
I dunno if this is a bug or how it's actually supposed to be, but try this in 1.4.0pre6:
First, edit the nearstars.stc so that Sol is a K5III star with AbsMag -0.6 (this is basically replacing Sol with Aldebaran - I wanted to see what the solar system would be like with a red giant in the middle of it
).
While mucking around and marvelling at the fact that the sun would take about 2.5 hours to rise from Earth... I noticed something a bit strange. Head on over to this URL:
cel://PhaseLock/Sol:Earth/Sol/2003-11-22T14:52:11.23767?x=VGY+iq7rFYPFDA&y=JBX0xEF59////////////w&z=neO+6AiF3oHy/////////w&ow=0.258718&ox=0.103411&oy=-0.959997&oz=0.027873&select=Sol:Earth&fov=30.626108&ts=1.000000<d=0&rf=104343&lm=2
Here, we're hovering over the Earth, looking at the swollen sun. Off to the right there is the Moon, which is about to "eclipse" the sun - well, actually, it's going to transit it, since it only covers a tiny fraction of the disc now.
Now split the view between the Earth and the Sun, and fastforward time. Watch what happens to Earth as the moon crosses the solar disc - it gets very much darker as the transit progresses, and between about 23:00 and 24:00 UTC on 23rd November you can even see what looks like the top of a solid shadow clipping Antarctica.
Now, I don't think this is what would really happen. The moon is only blocking out about 1/40th of the solar disc, and the illumination shouldn't drop THAT much (especially given that it seems to be darkest when the moon is nearest the centre of the solar disc as seen from Earth). And you shouldn't see any solid shadow of the moon either. Either way, it's not very realistic - there should only be a slight drop in illumination on Earth as the moon transits the red giant disc.
So is this a bug, or is this just something that Celestia can't handle yet?
First, edit the nearstars.stc so that Sol is a K5III star with AbsMag -0.6 (this is basically replacing Sol with Aldebaran - I wanted to see what the solar system would be like with a red giant in the middle of it
).
While mucking around and marvelling at the fact that the sun would take about 2.5 hours to rise from Earth... I noticed something a bit strange. Head on over to this URL:
cel://PhaseLock/Sol:Earth/Sol/2003-11-22T14:52:11.23767?x=VGY+iq7rFYPFDA&y=JBX0xEF59////////////w&z=neO+6AiF3oHy/////////w&ow=0.258718&ox=0.103411&oy=-0.959997&oz=0.027873&select=Sol:Earth&fov=30.626108&ts=1.000000<d=0&rf=104343&lm=2
Here, we're hovering over the Earth, looking at the swollen sun. Off to the right there is the Moon, which is about to "eclipse" the sun - well, actually, it's going to transit it, since it only covers a tiny fraction of the disc now.
Now split the view between the Earth and the Sun, and fastforward time. Watch what happens to Earth as the moon crosses the solar disc - it gets very much darker as the transit progresses, and between about 23:00 and 24:00 UTC on 23rd November you can even see what looks like the top of a solid shadow clipping Antarctica.
Now, I don't think this is what would really happen. The moon is only blocking out about 1/40th of the solar disc, and the illumination shouldn't drop THAT much (especially given that it seems to be darkest when the moon is nearest the centre of the solar disc as seen from Earth). And you shouldn't see any solid shadow of the moon either. Either way, it's not very realistic - there should only be a slight drop in illumination on Earth as the moon transits the red giant disc.
So is this a bug, or is this just something that Celestia can't handle yet?