Grades K–2 · Earth & Space
Why are other stars hard to see during the day?
The stars do not switch off when morning comes. Their light still travels toward Earth. The Sun is a star too, but it is much closer to us than the other stars, so it looks far brighter in our sky.
In the diagramThe stars stay when the sky brightensSunlight scattered in air brightens the day sky.Stars remain when the bright sky hides them.
Air around Earth scatters sunlight, sending some of it in new directions. That makes the daytime sky bright even where we are not looking straight toward the Sun. The faint light from distant stars is difficult to pick out against this bright background.
When our part of Earth turns away from the Sun, a clear sky can grow dark enough for more stars to stand out. Their light did not suddenly begin. What changed was the bright background that had hidden it. Something can be present even when it is hard to see.
About this explanation
Starting knowledge: Recognize daytime and nighttime skies and compare a bright background with a dark one.
Sources
- NASA Goddard Space Flight Center — Imagine the Universe: Earth Questions
- NASA — Why Can You See the Moon During the Day?