Moon, Sun & Universe
Your complete astronomy observation toolkit — from golden hour planning to deep-sky telescope alignment. Every tool runs 100% in your browser, no signup required.
Explore Astronomy Tools
Solar Insight Pro
Golden hour calculator, sunrise sunset time, sun position tracker, UV index, and laundry daylight forecast — all in your browser.
MoonSync
Moon phase calendar, lunar calendar, moonrise moonset calculator, and lunar surface illumination — all in your browser.
Sidereal Time Calculator
Local sidereal time calculator for telescope alignment — compute LST & GST from any UTC date and longitude — offline, no upload.
Coord Converter
Free latitude longitude converter: WGS84, GCJ02 (China Mars), BD09 (Baidu) coordinate systems — no upload, 100% in your browser.
Telescope FOV Calculator
Telescope FOV calculator: eyepiece field of view, magnification, exit pupil, and CCD sensor coverage — all in your browser.
Planetary Hour Calculator
Classical Chaldean planetary hours for any date and location — calculated in your browser.
Twilight Calculator
Dusk and dawn calculator: find civil, nautical, and astronomical twilight times for any date and location — zero upload.
Astronomy Fundamentals
What Is the Golden Hour?
Golden hour occurs shortly after sunrise and before sunset when sunlight travels through more atmosphere, producing soft, warm light ideal for landscape and architectural photography. Use Solar Insight Pro to find exact times for any location.
How Moon Phases Affect Observation
A bright full moon washes out faint deep-sky objects like galaxies and nebulae. The best observation nights fall around the new moon when the sky is darkest. MoonSync shows illumination percentage and rise/set times.
Why Sidereal Time Matters
Earth rotates once every 23h 56min relative to the stars (sidereal day), not 24h. Telescope mounts use local sidereal time (LST) to track celestial objects. Our calculator converts UTC to LST for precise alignment.
Astronomical vs Civil Twilight
Civil twilight is bright enough for outdoor photography without artificial light. Astronomical twilight is when the sky is truly dark — essential for deep-sky astrophotography. Know the difference to plan your session.