Bluehour

Bluehour brings you one city skyline a day, photographed during the blue hour —
that short stretch of twilight after sunset and before sunrise when the sky turns
a deep luminous blue and the city lights take over. It is the most photogenic
light a skyline ever gets, and it never lasts long. Open the app once a day and
you get that moment somewhere in the world, without hunting for it.

Every day Bluehour picks the same city for everyone, so the skyline you see is
the skyline the whole world sees that day. Tap through to read what makes the
city worth knowing, look up its tallest building, check the local time, and find
out exactly when its next blue hour begins. Save the ones you love into your own
collection, and set any of them as your wallpaper in a single tap. You can also
page back through the past week to catch up on skylines you missed.

KEY FEATURES
✓ A city of the day — a real blue-hour skyline photograph, the same one for
everyone, refreshed at midnight UTC
✓ Twilight Now — a live board of which cities on Earth are in their blue hour,
golden hour or pre-dawn glow at this exact moment, counting down in real time
✓ World atlas — all 50 cities on a twilight world map, with search, filters for
seen, saved and not-yet-visited, and sorting by name, continent or height
✓ One-tap wallpaper — set any skyline on your home and lock screens, cropped to
your screen so it looks exactly like what you saw in the app
✓ Your collection — save the skylines you love and watch your map fill in, with
a running count of cities, countries and continents
✓ City facts — the tallest building and the year it was completed, coordinates,
time zone, live local time and the next evening blue hour, all on one screen
✓ Twilight bells — tap the bell on any city to be reminded shortly before its
blue hour begins
✓ A gentle daily reminder at a time you choose, so you never miss the day's city

HOW IT WORKS
1. Open Bluehour and see today's skyline, with the city's story beneath it.
2. Tap the star to keep it, or Wallpaper to put it on your screen right away.
3. Visit Twilight Now to see where on Earth the light is happening right now.
4. Explore the atlas, and watch your collection grow one twilight at a time.

WHY BLUEHOUR
No account, no sign-up, no ads and nothing to buy. The astronomy is computed on
your device using the NOAA solar position algorithm, so the phase and countdown
for every city are accurate to the minute whether or not you have a connection.
Skylines you have saved are kept on your device and still open when you are
offline. The whole app is built around one calm daily moment rather than a feed
that wants your attention all day.