Light pollution does not blot stars out. It raises the floor. Every streetlight, shop sign and floodlight in the west of Singapore throws light upward, the atmosphere scatters it, and the whole sky starts glowing faintly. A star is only visible when it is brighter than the background it sits on — so as the background brightens, the faintest stars stop standing out, one after another, from the bottom up.
That is why the effect is so uneven, and why the observatory still works. The Moon is about 400,000 times brighter than the sky glow. Jupiter, Saturn, Venus and the bright double stars are also far above the floor. Raising the floor does nothing to them at all. But the Milky Way is a broad, faint, low-contrast glow — almost exactly the same kind of light as the pollution itself — so it is the first thing to drown, and it drowns completely.
| Target | From here | Why |
|---|---|---|
| The Moon | Perfect | Utterly unaffected. Craters, mountains and the terminator look exactly as good from a city car park as from a desert. Our best object, most nights. |
| Planets — Jupiter, Saturn, Venus, Mars | Perfect | Thousands of times brighter than the sky glow. Saturn's rings and Jupiter's belts are a matter of steady air, not dark skies. |
| Double & coloured stars | Perfect | Splitting a pair depends on the telescope and the seeing, never on darkness. Albireo's gold-and-blue is as good here as anywhere. |
| Bright star clusters — M13, Omega Centauri, the Pleiades | Good | Concentrated points of light punch through the glow. You lose the faint outer halo; the core is still spectacular. |
| The brightest nebulae — Orion, Lagoon, Eta Carinae | Reduced | Visible, but a ghost of a dark-sky view. This is where a narrowband filter earns its keep, blocking the streetlight wavelengths while passing the nebula's own. |
| Galaxies beyond Andromeda | Mostly lost | Large, faint and diffuse — the worst possible combination. Most are simply not there from Jurong, and no filter helps, because a galaxy emits across all wavelengths. |
| The Milky Way to the naked eye | Gone | Needs a genuinely dark sky. From here the galactic centre is high overhead in mid-year and still invisible without a camera. |
1. Your eyes are still adapting. Full dark adaptation takes 20–30 minutes and a single glance at a phone screen undoes most of it. The difference between arriving and half an hour later is larger than most people expect — this is why we ask for red light only.
2. It is recent, and it is reversible. Nearly everyone alive in Singapore before the 1970s could see the Milky Way from here. Light pollution is unusual among environmental problems in that it stops the instant the light is switched off or aimed downward — nothing has to be cleaned up, and nothing is permanent.
3. The sky is still there. Every object in the eyepiece tonight is the real thing, at the real distance, and the photons landing on your retina left Saturn about eighty minutes ago. A bright sky changes what is easy to see. It changes nothing at all about what is up there.