Sun
Reference data for the Sun: 5,772 K effective temperature, 1.00 AU mean distance, photospheric angular diameter, and fundamental solar constants.
Provenance-Backed Scientific Measurements
Every measurement below preserves its unit, uncertainty interval, observational method, reference epoch, quality status, and primary catalog source. See Uncertainty & Provenance for how competing measurements are handled.
| Parameter | Value | Uncertainty | Method & Epoch | Quality Status | Source Archive |
|---|---|---|---|---|---|
| Apparent Magnitude (V) | -26.74 mag | ± 0.01 mag | JPL Horizons DE440/441 planetary and satellite ephemeris solution | definitive | NASA/JPL Solar System Dynamics & Planetary Fact Sheets |
| Absolute Magnitude (V) | 4.83 mag | ± 0.01 mag | JPL Horizons DE440/441 planetary and satellite ephemeris solution | definitive | NASA/JPL Solar System Dynamics & Planetary Fact Sheets |
| Mean Earth-Sun Distance | 1 AU | ± 0.00001 AU | 149,597,870.7 km (~8.317 light-minutes); varies between 0.9833 AU at perihelion and 1.0167 AU at aphelion. | definitive | NASA/JPL Solar System Dynamics & Planetary Fact Sheets |
| Mean Angular Diameter | 31.99 arcmin | ± 0.53 arcmin | Varies from 31.46′ in early July to 32.53′ in early January. | definitive | NASA/JPL Solar System Dynamics & Planetary Fact Sheets |
| Nominal Effective Temperature | 5772 K | ± 1 K | IAU 2015 Resolution B3 nominal solar effective temperature. | definitive | NASA/JPL Solar System Dynamics & Planetary Fact Sheets |
| Solar Age | 4.567 Gyr | ± 0.001 Gyr | Lead-lead radiometric dating of calcium-aluminum-rich inclusions (CAIs) in primitive chondrites. | definitive | NASA/JPL Solar System Dynamics & Planetary Fact Sheets |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots The Sun (Sol) — G2V Star & Solar System Data at RA 18h 00m 00.00s, Dec -23° 26′ 21.4″ within Sagittarius, alongside peak meridian transit altitudes for 40°N and 30°S observers. Use the RA/Dec Coordinate Converter to compute exact culmination altitude for your latitude.
Astrophysical Context & Structure
As the only star whose surface granulation, magnetic flux tubes, and interior acoustic oscillations can be resolved in exquisite detail, the Sun serves as the fundamental benchmark for stellar astrophysics. Spanning 1,391,400 kilometers across the photosphere (109.2 Earth radii) and weighing 1.9885 × 10³⁰ kilograms (332,950 Earth masses), it accounts for 99.86 percent of the total mass of the Solar System. Every 11 years, its differentially rotating convection zone reverses magnetic polarity through the Schwabe sunspot cycle, driving solar flares, coronal mass ejections, and heliospheric space weather.
In the central core—where temperatures reach 15.7 million kelvin and densities approach 150 grams per cubic centimeter—the proton-proton chain fuses roughly 600 million metric tons of hydrogen into helium every second, converting 4.26 million metric tons of mass into 3.828 × 10²⁶ watts of radiative energy. Photonsdiffuse slowly outward through the radiative zone over ~170,000 years before convective plumes carry heat to the 5,772 K photosphere. Above the visible disk, magnetic reconnection and Alfvén waves heat the tenuous solar corona above 1 to 2 million kelvin.
Because the Sun shines at visual magnitude -26.74, viewing it through any unfiltered optical instrument causes immediate, permanent retinal damage. Equipped with certified ISO 12312-2 front-aperture white-light filters or dedicated narrowband H-alpha (656.28 nm) and Calcium-Kalon etalons, amateur observers track sunspot umbrae, penumbral filaments, faculae, andarching chromospheric prominences daily.
Practical Visual Observing Guide
- NEVER view the Sun without a purpose-built, certified front-aperture solar filter; unfiltered optical concentration causes instantaneous blindness.
- White-light solar filters reveal photospheric sunspot groups, granulation, and limb darkening.
- Dedicated H-alpha solar telescopes (<0.7 Å bandpass) reveal chromospheric prominences, filaments, spicules, and active-region flares.
Catalog Cross-Identifications & Aliases
Common Aliases: Sol · Solar Star · G2V Reference Star
| Catalog Authority | Identifier |
|---|---|
| SIMBAD | Sun |
Related Objects, Comparisons & Guides
The Moon (Luna) — Orbital & Physical Data
Reference data for Earth's Moon: 27.32-day sidereal period, 384,400 km semi-major axis, laser-ranging recession, and lunar observing metrics.
Mercury — Orbital & Physical Reference Data
Reference data for Mercury: 87.97-day eccentric orbit, 3:2 spin-orbit resonance, iron-rich interior structure, and twilight elongation limits.
Sirius (Alpha Canis Majoris Binary)
Coordinates, Hipparcos parallax (379.21 mas, 8.60 ly), magnitude −1.46, Sirius B white dwarf orbit, and observing guide for Sirius.
Apparent vs Absolute Magnitude Explained
Understand the logarithmic Pogson astronomical magnitude scale, apparent visual magnitude (m), absolute magnitude (M at 10 parsecs), and bolometric corrections.
Stellar Spectral Classification (OBAFGKM)
Reference guide to Morgan-Keenan (MK) stellar classification (O B A F G K M), luminosity classes (I–V, WD), color index (B-V), and the H-R diagram.
Scientific Sources & Dataset Provenance
- NASA/JPL Solar System Dynamics & Planetary Fact Sheets (DE441 (2021/2026)): Park, R. S., et al. 2021, AJ, 161, 105 (The JPL Planetary and Lunar Ephemerides DE440 and DE441) — NASA Jet Propulsion Laboratory / GSFC