A faint cone of light rising along the ecliptic, in the west after dusk in spring and in the east before dawn in autumn. It is sunlight scattered by dust in the Solar System. You need a very dark sky to see it.
Related terms
- Ecliptic
The Sun’s apparent path among the stars over the year, mirroring the plane of the Earth’s orbit. It is tilted by 23.4° to the celestial equator. The Moon and planets always stay close to it, which helps to recognise them.
- Light pollution
Artificial lighting that brightens the night sky and drowns faint stars, nebulae and the Milky Way. A dome of light spreads for tens of kilometres around towns. It also harms wildlife and health; some towns now switch off street lights in the middle of the night.
- Twilight
The period when the sky darkens after sunset. It is civil until the Sun is 6° below the horizon (you can read outside), nautical until 12° (the horizon fades) and astronomical until 18°. Only then is the night truly dark for deep-sky objects.
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