The Moon is the king of the night sky and almost completely absent during the day. Why does the moon appear brighter at night? Let us explore more.
Light & the Human Eyes
Human eyes see the image of the objects, which are composed of the light reflected from the things we look at (camera operates on the same principle). The greater the light from the object entering our eyes brighter the object. An object can direct light towards our eyes either by creating and emitting light of its own or by reflecting light that already exists.
Types of Objects
I. Light Emitting Objects
There are certain objects around us that produce and emit their own light such as the stars, sun (a type of star), bulbs, tube-lights etc.
II. Objects reflecting light
All other objects in the universe that do not have their own light are visible to us because they reflect the light that falls on them from light emitting objects.
Difference between the Visibility of both objects
- The objects that generate their light seem comparatively brighter than other nearby objects that reflect borrowed light.
- In space, stars produce significant amounts of visible light and hence are some of the brightest objects in the universe, unlike planets and moons that do not generate their visible light.
- The reason we can see some planets and moons is that they reflect light from the Sun.
- The brightness of these celestial objects depends on the amount of reflected light from these bodies perceived by our eyes.
Factors determining the brightness of an object
The brightness of a planet or Moon as perceived by us depends on three factors:
- The materials on its surface and atmosphere, as well as it’s surface roughness,
- The total amount of sunlight incident on the object, and
- The distance between the object and the eye or camera viewing it.
Snow, rough ice, and clouds are highly reflective but most types of rock are not. A planet or Moon surrounded by clouds and covered with snow or rough ice is generally brighter than a planet or Moon with a rocky surface with no atmosphere. Planets and moons closer to the Sun catch more sunlight and thus usually have a higher perceived brightness. Also, planets and moons more proximate to the earth generally have a higher perceived brightness as seen from the earth because more of their reflected light reaches the earth.
The Moon’s Position
- The Moon looks brighter than any other planet or Moon of the solar system because the Moon is closest to the earth.
- The Moon’s surface is dark gray and has a bumpy and rocky surface, and it can reflect only 12% of the light that falls on it.
- The Moon revolves around the earth in orbit.
- A Full Moon occurs when the Moon has moved in its orbit so that the Sun and the Moon are aligned on opposite sides of the earth, and the Moon’s face is illuminated by the Sun without any interference from the earth. During a Full moon night, the Moon is bright, and it outshines fainter objects. When the Moon is at the point in its orbit closest to The earth, it is called a super moon as it is almost 20% brighter than usual.
- Sometimes the Moon can be seen even during the day. The size and the proximity of the Moon from the earth makes it so bright that it can sometimes be seen during the day.
- During the day, the Sun’s light is so bright that it is impossible to see less bright, far away objects in the sky. These other astronomical bodies – planets and stars – can only be seen at night when the Sun’s light is not present to outshine them.
Why does the moon appear brighter at night?
The Moon appears bright in the night sky because everything else is dark in comparison. Also, the sun and its bright light is absent to outshine the moon.
The brightness of the moon can be understood with a simple example of the night lamp. Even if switched on during the day, it is almost not visible. But at night time when no other light source is present, the little lamp shines bright.
Did you know that the Moon is moving away from the earth at almost 4 cm per year? Also read more to know if the world will end in 2038.