-
Asked by anon-251648 to Rosanna on 30 Apr 2020.
Question: if the moon is a mirror of the sun then why does the sky get dark
- Keywords:
-
Rosanna Tilbrook answered on 30 Apr 2020:
Nice question! You’re right, the Moon does reflect the Sun’s light, but it doesn’t reflect enough of it to make the night sky bright. The amount that something reflects light is called its albedo, with 1 meaning all light is reflected and 0 meaning no light is reflected (instead, it’s all absorbed). The moon has an albedo of around 0.12, so it only reflects about 12% of the light that shines on its surface. As well as this, the Moon only intercepts a small amount of the light that the Sun radiates into space. If the moon was larger, it would be able to reflect more light.
Comments
olegshebanits commented on :
To add to Rosanna’s answer, the sky during a full moon sure is dark, but not as dark as the sky with no moon. For instance, faint stars and Milky Way will not be visible during a full moon.
The moon is bright enough to cause a cool optical phenomenon called halo – when there is a light haze in the sky, there will be a rainbow ring around the moon. The colours may be difficult to see with just your eyes because when light is faint we only see in black-and-white – but a camera should pick it up.
A fun comparison of objects illuminated by sunlight vs moonlight: even the darkest fabric like black velvet under sunlight is brighter than fresh white snow under moonlight.
NuclearJames commented on :
You are right the moon does reflect a great deal of sunlight. But the moon is also orbiting around the earth, and is much smaller, this means sometimes earth either partly or completely blocks light from from the sun reaching the moon, just like when you step in the shade. The moon might even be on the other side (day side) of earth, sometimes you may have seen the moon in the sky during the day, or you may have been lucky enough to see a solar eclipse.