Solar system data, stellar classification, constants, deep sky objects.
Solar System
| Body | Type | Mass (kg) | Diameter (km) | Dist. from Sun (AU) | Orbital Period | Moons |
|---|---|---|---|---|---|---|
| Sun | Star | 1.989×10³⁰ | 1,392,700 | 0 | — | — |
| Mercury | Planet | 3.30×10²³ | 4,879 | 0.387 | 88 days | 0 |
| Venus | Planet | 4.87×10²⁴ | 12,104 | 0.723 | 225 days | 0 |
| Earth | Planet | 5.97×10²⁴ | 12,742 | 1.000 | 365.25 days | 1 |
| Mars | Planet | 6.42×10²³ | 6,779 | 1.524 | 687 days | 2 |
| Jupiter | Gas Giant | 1.90×10²⁷ | 139,820 | 5.203 | 11.86 years | 95 |
| Saturn | Gas Giant | 5.68×10²⁶ | 116,460 | 9.537 | 29.46 years | 146 |
| Uranus | Ice Giant | 8.68×10²⁵ | 50,724 | 19.19 | 84.01 years | 28 |
| Neptune | Ice Giant | 1.02×10²⁶ | 49,244 | 30.07 | 164.8 years | 16 |
| Pluto | Dwarf Planet | 1.31×10²² | 2,376 | 39.48 | 248 years | 5 |
| Moon | Natural satellite | 7.34×10²² | 3,475 | 1.00 (from Earth) | 27.3 days | — |
Stellar Classification (Harvard)
| Class | Color | T_surface (K) | Example Stars |
|---|---|---|---|
| O | Blue | ≥ 30,000 | Mintaka, Naos |
| B | Blue-white | 10,000–30,000 | Rigel, Spica |
| A | White | 7,500–10,000 | Sirius, Vega |
| F | Yellow-white | 6,000–7,500 | Procyon, Canopus |
| G | Yellow | 5,200–6,000 | Sun, Alpha Centauri A |
| K | Orange | 3,700–5,200 | Arcturus, Epsilon Eridani |
| M | Red | 2,400–3,700 | Betelgeuse, Proxima Centauri |
Key Constants & Units
| Constant / Unit | Value | Description |
|---|---|---|
| Astronomical Unit (AU) | 1.496 × 10¹¹ m | Earth–Sun mean distance |
| Light-year (ly) | 9.461 × 10¹⁵ m | Distance light travels in 1 year |
| Parsec (pc) | 3.086 × 10¹⁶ m = 3.26 ly | 1 AU / 1 arcsecond of parallax |
| Hubble Constant H₀ | ≈ 70 km/s/Mpc | Universe expansion rate |
| Speed of light c | 2.998 × 10⁸ m/s | Maximum signal speed |
| Schwarzschild radius | r_s = 2GM/c² | Event horizon of black hole of mass M |
| Solar luminosity L☉ | 3.828 × 10²⁶ W | Sun's total power output |
| Age of universe | 13.8 × 10⁹ years | From CMB observations |
Deep Sky Objects
| Object | Type | Distance | Notes |
|---|---|---|---|
| Andromeda (M31) | Galaxy | 2.537 Mly | Nearest major galaxy; will collide with Milky Way in ~4.5 Gyr |
| Orion Nebula (M42) | Emission nebula | 1,344 ly | Stellar nursery, visible naked eye |
| Crab Nebula (M1) | Supernova remnant | 6,500 ly | SN 1054; pulsar at center |
| Pleiades (M45) | Open cluster | 444 ly | 7 Sisters, young hot B stars |
| Sagittarius A* | Supermassive BH | 26,000 ly | Milky Way center; 4 × 10⁶ M☉ |
| Hubble Deep Field | Galaxy cluster field | Various | ~3,000 galaxies in tiny patch of sky |
