Object Comparison

[Anthony_B_Russo10]

This addon compares the sizes of all the Solar System asteroids in Celestia, along with 3 comets, the 9 Major bodies, a Brown Dwarf, Teegarden's Star, Proxima Cen, Alpha Cen B, Sol, Sirius A, Procyon, Rigel, and an O type star. The folder contains two builds, one for 1.6.1 with the brown dwarf with spectral type T9, and one for 1.7.0 with the brown dwarf at its correct spectral type of Y2.

The above image is of the 1.7.0 build.

These are of the 1.6.1 build.

[Joey P.]

Nice!

[Joey P.]

What about putting the Danny Phantom stars in it?

[Joey P.]

Remember this older one comparing various giant stars including the red giant Sun?
viewtopic.php?f=6&t=11257&p=145647#p145647

[Sirius_Alpha]

What about putting the Danny Phantom stars in it?

The point of the add-on was to compare the sizes of various (real) astrophysical objects.

[Lafuente_Astronomy]

What about putting the Danny Phantom stars in it?

You can make your own comparison thread with the fictional stars you've made. This one's for real objects, as what Sirius_Alpha said.

[Joey P.]

Also, the object comparison is right behind Alpha Centauri as seen from Earth, but its combined apparent and absolute magnitudes are so bright that Alpha Centauri is lost in the glare.

[Anthony_B_Russo10]

I upped the distance of the barycenter to 1000 light years.

[Joey P.]

Nice

[Joey P.]

This is the code for a modification that slightly changes the position of the comparison and turns the base star into Danny Phantom (though 12 times smaller than he should be). It also adds "2" to the stars involved so that they are not involved in anything else.

Code: Select all

Barycenter "Object Compare"
{
   RA  220.899437 # mass ratio 1.12:0.93
   Dec -70.835401 #
   Distance 1000.365
}

"Daniel Danny Fenton 2:Danny Phantom 2:Danny Clone:Daniel Fenton 2:Daniel 2:Danny 2:Danny Fenton 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "Q"
   AbsMag 4.9
   Texture "bstar.*"
    Radius 1.0

   EllipticalOrbit {            
      Period           79.85
      SemiMajorAxis    00.00 # mass ratio 1.12:0.93
      Eccentricity      0.00
      Inclination      00.00
      AscendingNode    00.00
      ArgOfPericenter   0.00
      MeanAnomaly     000.00
   }         
}

"WISEPA J182831.08+265037.8"
{
   OrbitBarycenter "Object Compare"

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.00573587709
   Eccentricity      0.0000000
   Inclination       0.1000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }

   SpectralType "T9"
   AbsMag 8.83
   Radius 85790.4
   Texture "browndwarf.jpg"

   UniformRotation
   {
       Period         609.12  # 25.38 days
       Inclination      7.25
       AscendingNode   75.77
       MeridianAngle   23.00  # standard meridian
   }
}

"Teegarden's Star 2"
{
   OrbitBarycenter "Object Compare"

   SpectralType "M6.5V"
   AppMag 15.14
   Radius 88392

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.007072794519
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Proxima Cen 2"
{
   OrbitBarycenter "Object Compare"

   SpectralType "M5.0V"
   AppMag 11.05
   Radius 107323.2

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.009078170656
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"ALF cen B 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "K1V"
   AppMag 1.34
   Radius 600787.2

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.0170996752
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }      
}

"Sol 2:Sun 2"
{
   OrbitBarycenter "Object Compare"
   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.02645809717
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }   

   SpectralType "G2V"
   AbsMag 4.83

   UniformRotation
   {
       Period         609.12  # 25.38 days
       Inclination      7.25
       AscendingNode   75.77
       MeridianAngle   23.00  # standard meridian
   }
}

"Sirius A 2:Alhabor A 2:ALF CMa A 2:9 CMa A 2:Gliese 244 A 2:ADS 5423 A 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "A1V"
   AppMag -1.43
   Radius 1340000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.04210003104
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Procyon A 2:Elgomaisa A 2:ALF CMi A 2:10 CMi A 2:Gliese 280 A 2:ADS 6251 A 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "F5IV"
   AppMag 0.37
   Radius 1425408

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.06656561991
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Rigel 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "B8I-a"
   AppMag -36.25
   Radius 50500000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.454271673
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Pismis 24-1 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "O3"
   AppMag -38.68
   Radius 149000000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     2.11873386644
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}




[Fafers_br]

Talking about object comparison, and apologizing for drifting a little offtopic, this topic reminded me of an issue I observed in my Celestia 1.6.0 (Yes, I know...).
Once upon a time, in a not so far away galaxy, I had the idea of making a comparison of object sizes putting them side by side in a vertically splited view. To my total surprise, I observed that a Brown Dwarf with a radius of 74400Km was visually larger than a planet with a radius of 78171Km, both seen from the same distance and FOV. Please, see the image below.

Well, I figured out that the issue arises in the planet side. When one calculates the angular diameter for the Brown Dwarf, the value is correct. The same does not happen to the planet. The angular diameter of the planet should be ~27°52' using the equation:
angdiam=2arcsin[diameter/(2*dist)]
But as you can see in the image, the apparent diameter of the planet, given by Celestia, is ~22°23'.

Is this an issue? Or a silly mistake of mine?

[Anthony_B_Russo10]

It's fine.

[Joey P.]

This update adds more stars:

Code: Select all

Barycenter "Object Compare"
{
   RA  220.899437 # mass ratio 1.12:0.93
   Dec -70.835401 #
   Distance 1000.365
}

"Daniel Danny Fenton 2:Danny Phantom 2:Danny Clone:Daniel Fenton 2:Daniel 2:Danny 2:Danny Fenton 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "Q"
   AbsMag 4.9
   Texture "daniel.*"
    Radius 1.0

   EllipticalOrbit {           
      Period           79.85
      SemiMajorAxis    00.00 # mass ratio 1.12:0.93
      Eccentricity      0.00
      Inclination      00.00
      AscendingNode    00.00
      ArgOfPericenter   0.00
      MeanAnomaly     000.00
   }         
}

"WISEPA J182831.08+265037.8"
{
   OrbitBarycenter "Object Compare"

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.00573587709
   Eccentricity      0.0000000
   Inclination       0.1000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }

   SpectralType "T9"
   AbsMag 8.83
   Radius 85790.4
   Texture "browndwarf.jpg"

   UniformRotation
   {
       Period         609.12  # 25.38 days
       Inclination      7.25
       AscendingNode   75.77
       MeridianAngle   23.00  # standard meridian
   }
}

"Teegarden's Star 2"
{
   OrbitBarycenter "Object Compare"

   SpectralType "M6.5V"
   AppMag 15.14
   Radius 88392

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.007072794519
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Proxima Cen 2"
{
   OrbitBarycenter "Object Compare"

   SpectralType "M5.0V"
   AppMag 11.05
   Radius 107323.2

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.009078170656
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"ALF cen B 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "K1V"
   AppMag 1.34
   Radius 600787.2

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.0170996752
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }       
}

"Sol 2:Sun 2"
{
   OrbitBarycenter "Object Compare"
   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.02645809717
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }   

   SpectralType "G2V"
   AbsMag 4.83

   UniformRotation
   {
       Period         609.12  # 25.38 days
       Inclination      7.25
       AscendingNode   75.77
       MeridianAngle   23.00  # standard meridian
   }
}

"Sirius A 2:Alhabor A 2:ALF CMa A 2:9 CMa A 2:Gliese 244 A 2:ADS 5423 A 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "A1V"
   AppMag -1.43
   Radius 1340000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.04210003104
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Procyon A 2:Elgomaisa A 2:ALF CMi A 2:10 CMi A 2:Gliese 280 A 2:ADS 6251 A 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "F5IV"
   AppMag 0.37
   Radius 1425408

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.06656561991
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Vega 2:ALF Lyr 2:3 Lyr 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "A0V"
   AppMag -0.03
   Radius 1961891.6

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.1
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Regulus 2:ALF Leo 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "B8IV"
   AppMag -1.35
   Radius 2436700

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.175
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Spica 2:ALF Vir 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "B1V"
   AppMag -0.97
   Radius 5200614

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.25
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}


"Pollux 2:BET Gem 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "K0III"
   AppMag 1.14
   Radius 6126560

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.3656561991
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Alnitak 2:ZET Ori 2:50 Ori 2:126 G. Ori 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "O9.5Iab"
   AppMag -6
   Radius 13924000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.5356561991
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Arcturus 2:ALF Boo 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "K0III"
   AppMag -0.05
   Radius 17683480

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     0.7756561991
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Aldebaran 2:ALF Tau 2:87 Tau 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "K5III"
   AppMag 0.75
   Radius 30723306

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     1.16561991
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Rigel 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "B8I-a"
   AppMag -36.25
   Radius 50500000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     2.0454271673
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Pismis 24-1 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "O3"
   AppMag -38.68
   Radius 149000000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     3.91873386644
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"V382 Carinae 2:x Car 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "G5I"
   AppMag 3.68
   Radius 520000000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     10.91873386644
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Antares 2:Madeline Maddie Fenton 2:Madeline Fenton 2:Madeline 2:Maddie 2:Maddie Fenton 2:ALF Sco 2:21 Sco 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "M1.5Iab"
   AppMag -5.28
   Radius 557000000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     23.91873386644
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Betelgeuse 2:Jack Fenton 2:Jack 2:ALF Ori 2:58 Ori 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "M2Iab"
   AppMag -5.85
   Radius 661000000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     38.92773386644
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"Dash Baxter:Dash:DU Cru:SAO 252073"
{
   OrbitBarycenter "Object Compare"
   SpectralType "M2Iab"
   AppMag -5.52
   Radius 821516000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     50.92773386644
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}


[Sirius_Alpha]

Is this an issue? Or a silly mistake of mine?

The issue arises in the way Celestia calculates the "distance." For a planet, the distance is between the observer and the surface, whereas for a star, it is defined with respect to the centre of the star. If you "land" on the star's surface, you'll note you will have quite some "distance" still.

[Joey P.]

Mu Cephei, VV Cephei, and VY Canis Majoris (this uses textures only found in Celestia-ED):

Code: Select all

"MU Cep 2:Herschel's Garnet Star 2:Garnet Star 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "M2Iab"
   AppMag -5.52
   Texture "sunred3.*"
   Radius 988000000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     70.92773386644
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"VV Cep B 2:HD 208816 B 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "B0V"
   AppMag -1
   Radius 9050000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     80.92773386644
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"VV Cep A 2:HD 208816 A 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "M"
   AppMag -4.91
   Radius 1322780000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     95.92773386644
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}

"VY CMa 2"
{
   OrbitBarycenter "Object Compare"
   SpectralType "M4Ia"
   Texture "sunred4.*"
   AppMag -7
   Radius 1466000000

   EllipticalOrbit
   {
   Epoch       2452000.5        # 2001 Apr 1 00:00UT
   Period            1.0000
   SemiMajorAxis     115.92773386644
   Eccentricity      0.0000000
   Inclination       0.0000
   AscendingNode    00.00000
   ArgOfPericenter 000.00000
        MeanAnomaly     000.00000000
   }
}


[Fafers_br]

The issue arises in the way Celestia calculates the "distance." For a planet, the distance is between the observer and the surface, whereas for a star, it is defined with respect to the centre of the star. If you "land" on the star's surface, you'll note you will have quite some "distance" still.

Oh! Thank you, Sirius! So many years using Celestia and I had never noticed that! Shame on me.
After being enlighted on this matter, I was able to correctly display the comparison the way it was meant to be.

[Joey P.]

Full size comparison including large stars and Danny Phantom objects:

objectcomparewithdannyphantomandbigstars.zip

(1.2 MiB) Downloaded 413 times

[Joey P.]

Also, how do you tweak the glow color for the stars like what you have done with the red dwarf in the first picture? Thanks.

[SevenSpheres]

Also, how do you tweak the glow color for the stars like what you have done with the red dwarf in the first picture? Thanks.

It's toggled by the "%" key.

[Joey P.]

Oh, thanks!