Live Sky Map — Pick a location to see the sky above it tonight: bright stars, constellation lines, the Milky Way band and planet positions, with the galactic core (Milky Way center) marked. Drag and zoom to explore.
Where to go this week? — We combine the sunset glow forecast, moonlight stargazing conditions, and weather into one score per day for the next 7 days — so you know which day is worth heading out.
Aurora Forecast — Tonight's odds of seeing the aurora from New Zealand and the Arctic, using NOAA's OVATION model together with cloud, darkness and which way to look.
Photography Golden Hour Planner — Choose a city, date, and subject to get blue hour, golden hour, moon phase, and shooting tips. Use it before heading out for sunsets, city lights, coastlines, or a moonrise in the frame.
Tide Forecast — Check today and tomorrow tide times, tide charts, high tide, and low tide information for coastal planning and outdoor activities.
Intertidal Field Guide — Move from tide tables to the shore with three Taiwan field sites, their wildlife, access rules and safety limits.
Fishing Index — Today's best fishing windows computed from tide changes and the moon (solunar theory), for fishing ports and beaches around Taiwan, with a 7-day outlook.
Sunrise & Sunset — Calculate sunrise time, sunset time, golden hour, blue hour, and twilight periods by location and date for photography, travel, and daily planning.
Moon Phases — Check today's moon phase, last night's moon, upcoming full moon dates, lunar illumination, moonrise, moonset, and a monthly moon calendar.
UV Index — Check UV index by location and understand ultraviolet exposure levels for sun protection and outdoor planning.
Astronomy Calendar — Browse astronomical events by year, including meteor showers, solar eclipses, lunar eclipses, planetary oppositions, and other sky events.
Widgets — One iframe snippet adds a daily auto-updating sunrise & sunset card to your blog, B&B or surf-shop website. Completely free.
Go Timing — Combine sunrise, sunset, golden hour, moon, weather, UV, and tide data to decide whether today is good for photography, stargazing, or outdoor plans.
Explanations of what the sky is doing and why—when things happen, and how to check them yourself. Most lessons include a diagram whose numbers are calculated on the spot from orbital elements or the Earth–Moon–Sun teaching model, not typed in.
Opposition and conjunction — Use elongation to tell when a planet is visible all night or close to the Sun, and compare different Mars oppositions.
Greatest elongation — Why the two inner planets are always twilight objects, and why Venus is brightest as a crescent.
How auroras form — Follow the chain from sunspots and CMEs to the auroral oval, then use it to plan a realistic aurora trip.
Solar and Lunar Eclipses — The Moon's orbit leans 5.16 degrees, so most new and full moons do nothing at all. Turn the nodes and build a total eclipse, a ring, and a blood moon yourself.
How a meteor lights up — Textbooks say meteors burn from friction with the air. That sentence points at the wrong heat source. Drag altitude, speed and size, and see what is doing the heating.
The ecliptic plane — The solar system is a disc. Seen from the side it is a line, which is why the diagram has to say how much it is exaggerating.
Ptolemaic and heliocentric — One geometry, two choices of origin. Move the origin and the epicycles appear on their own.
Perihelion precession — The orbit itself turns. Watch the long axis sweep a few degrees over six thousand years, and meet Mercury's extra 43 arcseconds.
Tonight: stars, the Milky Way, sunset glow, or a cloud sea?
Stop cross-checking page by page. Start with tonight's stargazing index, find a dark-sky spot, confirm the galactic-core direction, or switch to sunset and cloud-sea planning.
Is tonight good for stars? — Cloud, transparency, moonlight and darkness are combined into the best observing window tonight.
Where is the sky darker? — Compare mountains, coasts and islands with Bortle, SQM, elevation, Milky Way timing and tonight's sky.
Which way is the Milky Way? — The live sky map marks the galactic core, planets, constellations and compass directions for field use.
Sunset glow or cloud sea? — A 7-day outdoor outlook blends sunset glow, stargazing and weather for photo and mountain plans.
Japan Milky Way travel — Achi, Bisei, Iriomote-Ishigaki, Kozushima and other Japanese star destinations with tonight's conditions.
Alert me when it is good — Dark-sky spot pages can be subscribed to with Telegram for evening stargazing alerts.