The dark is kept here.
Cerro Lumen sits at 2,840 m, fifty kilometres from the nearest streetlight. On moonless nights we open the dome to twelve visitors and point a 4.1 m mirror wherever they ask.
The dome
Thirty-one metres of aluminium that turns in four minutes. Inside, the floor is kept at the night's own temperature so the air above the mirror stays still.
- Across
- 31 m
- Light crosses it in
- —
The valley
A dark-sky reserve one hundred kilometres wide. The villages below agreed to amber, shielded lamps; from the summit their light is a faint ochre line on the horizon.
- Across
- 100 km
- Light crosses it in
- —
The Moon
The one thing we hide from. A full Moon brightens the sky forty times, so visitor nights follow its phase: we book the dark half of every month.
- Distance
- 384,400 km
- Its light reaches us in
- —
Saturn
The visitor favourite. Through the eyepiece the rings are sharp enough to show the gap a moon swept clean, and the light you see left the planet over an hour ago.
- Distance
- 1.43 billion km
- Its light reaches us in
- —
The galaxy
From the southern Andes the centre of the Milky Way passes straight overhead in winter. It casts a shadow on white paper. Bring some.
- Across
- 100,000 ly
- Light crosses it in
- 100,000 years
Tonight, from the summit.
Moon
—
Computed from today's date in your browser.
Sidereal time at the summit
—
The sky's own clock, at longitude 70.7° W. It runs four minutes a day faster than yours.
Next dark night
—
The first evening with less than a quarter of the Moon lit.
Choose a night.
Pick an evening to see what the sky will hold.