Example

Moon and stars, friends true and bright, ready listeners in the silent night, Their counsel, a wisdom from afar, the best companions beneath the cosmic star.

If we know the intrinsic brightness of an object in space - that is, how bright an object really is - then we can estimate its distance from how bright it appears to us from Earth.

• One type of standard candle is a 'Cepheid variable'. Cepheid variables are a...

Bright light in the mornings is crucial for an alertness boost, so a daily morning outdoors exercise routine is recommended.

Apart from that, warm and dim lighting at night promotes sleep.