天文学与空间

免费的500规则计算器用于天文摄影 — 立即找到避免星轨的最大快门速度，使用500规则、NPF规则和所有规则变体，适用于任何相机传感器。

免费天文摄影曝光计算器 — 使用500规则、400规则、300规则、NPF规则和板尺度方法计算最大未跟踪快门速度，以及基于信噪比的跟踪深空成像子曝光规划。

Free Delta-V (Δv) rocket equation calculator using the Tsiolkovsky equation. Solve for velocity change, initial mass, final mass, or Isp with multi-stage support, engine presets, and mission budgets.

Free Habitable Zone (HZ) Calculator using Kopparapu et al. (2013/2014) polynomial model — compute conservative and optimistic HZ boundaries, equilibrium temperature, stellar lifetime, snow line, ESI score, and more for any star.

Free Hohmann Transfer Orbit Calculator — compute delta-V burns, transfer time, orbital velocities, and propellant mass for transfers between two circular orbits or between planets.

免费哈勃常数 (H₀) 计算器 — 双向求解哈勃定律以获取退行速度、距离、红移和宇宙年龄，带有光谱线预设。

Free Light Year to Parsec Converter — instantly convert between light-years (ly), parsecs (pc), kiloparsecs (kpc), megaparsecs (Mpc), gigaparsecs (Gpc), astronomical units (AU), kilometers, and miles. Includes all-unit breakdown, cosmic scale indicator, famous distances reference, light travel time, parallax converter, and preset famous astronomical objects.

Free Lunar Eclipse Calculator — browse upcoming total, partial, and penumbral lunar eclipses from 2026 to 2032 with contact times, magnitude, visibility regions, and local time conversion.

Free Moon Phase Calculator — instantly find the current lunar phase for any date, including illumination percentage, moon age, upcoming phases, gardening guidance, and more.

Free Planet Orbital Period Calculator using Kepler's Third Law — compute orbital period, semi-major axis, or central body mass for any planet, moon, or exoplanet orbiting any star.

Free Stellar Parallax Distance Calculator — convert parallax angles to distances in parsecs, light-years, AU, and km. Includes preset famous stars, bidirectional mode, distance modulus, and precision tier analysis.

Free cosmological Redshift Calculator — compute recession velocity, luminosity distance, lookback time, and more from spectral wavelengths or redshift z using the ΛCDM model with Planck 2018 parameters.

Free Schwarzschild Radius (event horizon) calculator — compute the critical radius at which any mass becomes a black hole, surface gravity, average density, Hawking temperature, photon sphere, and ISCO radius.

Free Solar Eclipse Calculator — browse upcoming solar eclipses from 2025 to 2030, explore eclipse types (total, annular, partial, hybrid), view magnitude and obscuration data, contact times, Saros series, and countdown to the next solar eclipse event.

Free Star Magnitude Calculator — compute apparent magnitude, absolute magnitude, luminosity, distance modulus, and brightness ratios using the Pogson scale and distance modulus formula.

Free Sunrise and Sunset Calculator — find exact sunrise, sunset, solar noon, twilight, golden hour, and blue hour times for any location and date using the Jean Meeus / NOAA solar algorithm.

Free Telescope Magnification Calculator — instantly compute magnification, exit pupil, true field of view, resolution limits, and light grasp for any telescope and eyepiece combination. Supports Barlow lenses, focal reducers, and multi-eyepiece comparison.