Stars and planets evolve over time. Some features, like mass, remain roughly constant throughout their lives, others change quite dramatically. At the moment the program only handles stars on the Main Sequence, when they are stable. It assumes the star and planet are formed at the same time, and counts time from Zero Age Main Sequence (ZAMS), quoting values then and now. Extrapolate between them at your peril!
After the hard numbers, some commentary is given. This is the bit most likely to reflect my prejudices, so take things with a pinch of salt.
Hope you found this program useful!
John
| Feature | Sol | 47_Ursae_Majoris | Ratio | Comment |
|---|---|---|---|---|
| Type | G2 | F5 | ||
| Mass (M0) | 1.00 | 1.40 | 1.40 | Solar mass M0 = 1.99E+30 kg |
| Distance from Earth (ly) | 0.00 | 46.00 | 3.03E+06 | Light year = 9.47E+15 m |
| Age on Main Sequence (Gyr) | 10.00 | 3.90 | 0.39 | |
| Age (Gyr) | 4.60 | 0.00 | 0.00 | |
| Radius (R0) | 1.00 | 1.10 | 1.10 | Solar radius R0 = 6.96E+08 m |
| Surface gravity (m/s²) | 274.2 | 314.5 | 1.15 | |
| Escape Velocity (km/s) | 618 | 695 | 1.13 | |
| Luminosity (L0) | 1.00 | 1.53 | 1.53 | |
| Absolute magnitude Mv | 4.7 | 4.3 | ||
| Apparent magnitude mv | -26.9 | 5.0 | ||
| Surface temperature (K) | 5796 | 6137 | 1.06 | |
| Peak wavelength (micron) | 0.50 | 0.47 | 0.94 | |
| Ecosphere inner radius (AU) | 0.99 | 1.23 | 1.24 | |
| Ecosphere outer radius (AU) | 1.38 | 1.71 | 1.24 | |
| Star formation | ||||
| Luminosity (L0) | 0.71 | 2.55 | 3.59 | Solar luminosity L0=3.90E+26 W |
| Radius (R0) | 0.92 | 1.24 | 1.35 | Solar radius R0=6.96E+08 m |
| Absolute magnitude | 5.1 | 3.7 | ||
| Apparent magnitude | -26.6 | 4.4 | ||
| Temperature (K) | 5539 | 6570 | 1.19 | |
| Peak wavelength (micron) | 0.52 | 0.44 | 0.84 | |
| Ecosphere inner radius (AU) | 0.84 | 1.59 | 1.90 | |
| Ecosphere outer radius (AU) | 1.16 | 2.20 | 1.90 |
| Terran | 47_Ursae_Majoris | ||||||
|---|---|---|---|---|---|---|---|
| Feature | Earth | The_Moon | 47_Ursae_Majoris | No_Moon | 47_Ursae_Majoris/ Earth | No_Moon/ The_Moon | Comment |
| Formation | |||||||
| Rotation period (hr) | 21.96 | 0.00 | 59.85 | 250.00 | 2.73 | inf | -ve is retrograde |
| Temperature range of orbit (°C) | -38.6 to -43.2 | -13.9 to -19.0 | -63.4 to -73.6 | -29.6 to -41.4 | |||
| General | |||||||
| Type | Terrestrial | Terrestrial | Terrestrial | Terrestrial | |||
| Mean orbital distance (106 km) | 149.60 | 0.38 | 331.36 | 0.49 | 2.21 | 1.27 | Astronomical Unit=1.50E+08 km |
| Eccentricity | 0.020 | 0.060 | 0.050 | 0.050 | 2.50 | 0.83 | |
| Axial tilt (°) | 23.4 | 0.0 | 12.2 | 0.0 | 0.52 | nan | |
| Year (Earth days) | 365.2 | 27.3 | 1017.6 | 36.8 | 2.79 | 1.35 | |
| Star system escape velocity (km/s) | 42.12 | 42.12 | 33.49 | 33.49 | 0.80 | 0.80 | From planetary orbit |
| Angular diameter of star (°) | 0.53 | 0.53 | 0.27 | 0.27 | 0.50 | 0.50 | |
| Angular diameter of moon (°) | 0.52 | 1.91 | 0.59 | 1.91 | 1.13 | 0.84 | |
| Solar day (hr) | 24.00 | 11110.29 | 60.00 | 348.69 | 2.50 | 0.03 | |
| Radius (km) | 6370 | 1743 | 6776 | 2500 | 1.06 | 1.43 | |
| 1/Ellipticity | 294.1 | 300.0 | 300.0 | 300.0 | 0.98 | 1.00 | |
| Lithosphere | |||||||
| Mass (Earth Masses) | 1.00 | 0.01 | 0.01 | 0.03 | 1.12 | 2.50 | Earth Mass=5.98E+24 kg |
| Maximum Mass (Earth Masses) | 3211.7 | nan | nan | nan | nan | nan | |
| Density (kg/m³) | 5523 | 2696 | 5162 | 2284 | 0.93 | 0.85 | |
| Albedo | 0.33 | 0.00 | 0.45 | 0.00 | 1.36 | nan | |
| Inertia Factor | 0.34 | nan | nan | nan | nan | nan | |
| Typical surface gravity (m/s²) | 9.83 | 1.31 | 9.77 | 1.60 | 0.99 | 1.22 | |
| Equatorial surface gravity (m/s²) | 9.81 | 1.32 | 9.80 | 1.60 | 1.00 | 1.22 | |
| Polar surface gravity (m/s²) | 9.86 | 1.31 | 9.78 | 1.60 | 0.99 | 1.22 | |
| Escape velocity (km/s) | 11.19 | 2.14 | 11.51 | 2.82 | 1.03 | 1.32 | |
| Rotation period (hr) | 23.9 | 696.0 | 59.9 | 250.0 | 2.50 | 0.36 | -ve is retrograde |
| Shortest possible period (hr) | 2.63 | 3.77 | 2.72 | 4.09 | 1.03 | 0.70 | Any faster and planet breaks up |
| Geosynchronous orbit (km) | 35724 | 84021 | 73884 | 56319 | 2.07 | 0.67 | above the surface |
| Plate tectonics end (Gyr) | 5.10 | 0.19 | 5.54 | 0.37 | 1.09 | 1.92 | After this carbon is buried in the oceans (terrestrial planets only). |
| Maximum mountain height (m) | 16570 | 124062 | 16666 | 102090 | 1.01 | 0.82 | Mountains in practice smaller, terrestrial planets only |
| Horizon distance (m) | 3091 | 1617 | 3188 | 1936 | 1.03 | 1.00 | at eye level, 1.5 m |
| Atmosphere and Ocean | |||||||
| Atmospheric pressure (mbar) | 1013 | 0 | 1005 | 0 | 0.99 | nan | |
| Minimum RMM for atmosphere (g) | 2.54 | 69.37 | 2.40 | 39.80 | 0.95 | 0.57 | Gasses lighter than this escape over geological time (Hydrogen = 1) |
| Atmospheric RMM (g) | 33.84 | 0.00 | 33.77 | 0.00 | 1.00 | nan | |
| Specific heat capacity (cp) (J mol-1 K-1) | 27.6 | 0.0 | 27.0 | 0.0 | 1.0 | nan | |
| Speed of sound at surface (m/s) | 318.8 | 0.0 | 277.3 | 0.0 | 0.87 | nan | |
| Temperature range of orbit (°C) | -17.7 to 3.6 | -88.5 to -69.2 | -88.5 to -22.8 | -58.7 to 3.6 | Without greenhouse effect | ||
| Greenhouse effect (°C) | 36.00 | 0.00 | 36.00 | 0.00 | 1.00 | nan | |
| Typical surface temperature (°C) | 15.8 | 6.4 | -57.0 | -63.9 | With greenhouse effect | ||
| Scale height (m) | 7222 | 0 | 5446 | 0 | 0.75 | nan | |
| Dry adiabatic lapse rate (°C/km) | 12.07 | 0.00 | 12.22 | 0.00 | 1.01 | nan | |
| f (Coriolis effect) at 45°N * 1E4 | 1.03 | 0.04 | 0.41 | 0.10 | 0.40 | 2.78 | |
| Mid-ocean tide height (m) | 0.46 | 16.52 | 0.43 | 15.31 | 0.94 | 0.93 | |
Commentary
Terran system:
For The_Moon:
For No_Moon:
