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Do Planets Make Shadows?

Planets have been a fascination of people since the beginning of time.  We know much more today than the ancient people did, and yet the list of unanswered questions is endless. One of which is…can planets make shadows?  

Planets cannot make shadows. Solid bodies that come in the way of light cast a shadow but don’t cause shadows.  Since planets are solid bodies and not light sources, they can cast shadows when light shines on them, but they cannot be the light that makes the shadows appear.  

The planet Venus appears bright in the night sky, and it is for that reason it is referred to as the evening star. The reason Venus appears so bright is that a thick cloud covers it. This dense cloud reflects the sunlight that reaches it back into space, making it appear bright. Can a planet that seems bright make shadows?  

Does Venus Make a Shadow? 

For a shadow to be called a shadow, it has to have three parts: 

  • The Umbra: the darker inner part of a shadow
  • The Penumbra: the lighter part of the shadow where the light is only slightly obscured.
  • Ant-umbra:  is the area outside the shadow where the light is visible.

For a shadow to be called a shadow it also has to have the characteristics of a shadow, meaning it has to be cast because a solid object is in the way of a light source and is not permitting the light to travel through.  

Because Venus is a planet, it does not shine, but it reflects 70% of the Sun’s light, which gives it the appearance of a bright world. Venus is so bright that it can cause ‘shadows’ to form on the celestial bodies around it.  These shadows are not cast because of a source of light, it is caused by a reflection of light.  

The shadows caused by Venus are not classified as natural shadows because it only has the umbra part of the shadow and the ant-umbra, which is the light itself.  The Penumbra part of the shadow is absent.  Since the shadow cast by Venus is not light that is blocked by an object but rather reflected light blocked by an object.  

What Does the Shadow of Planet Earth do?  

Earth is a planet that casts a shadow. When the earth rotates around its axis, the part of the earth turned away from the Sun is in shadow. We can see the formation of this shadow as twilight turns to night.  When it is nighttime where you are, you are standing in the shadow that the earth casts on itself.  

The earth’s shadow is so big that it casts its shadow on the celestial bodies around it.  We see this in the phases of the moon.  The moon does not throw light but instead reflects the Sun’s light, so when the earth moves in the way of this light, it casts a shadow on the moon.

These shadows are visible to us as the moon appears to take different shapes during the phases. These phases are called: 

  • New moon
  • Waxing crescent moon
  • First-quarter  moon
  • Waxing gibbous moon
  • Full moon
  • Waning gibbous moon
  • Last quarter moon
  • Waning crescent moon

A solar eclipse is caused when the moon moves between the Sun and the earth.  The moon’s shadow will block the Sun’s light from reaching the planet, and this will appear to us in the form of a solar eclipse.  Since the moon is a lot smaller than the earth, the shadow it casts will not reach the entire globe therefor; the solar eclipse will only be seen in parts of the world.  

A lunar eclipse happens when the earth moves between the moon and the Sun.  The shadow of the planet is much bigger than the moon, and since the moon reflects the Sun’s light, the moon will be completely dark.  As the shadow of the earth moves over the moon, you will be able to see the moon fade away.  

When the earth moves in-between the moon and the Sun during a full moon, a total lunar eclipse takes place. Typically, a shadow will cast over the moon, making it dark, but during a blood moon, the Sun’s rays shine through the earth’s atmosphere, which in turn is reflected on the moon, making the moonshine red.  When the moon shines red, it is called a blood moon.  

Does the Sun have a Shadow? 

The Sun is a solid object, and tangible things that come in the path of light casts shadows, so we can say that the Sun could have a shadow.

However, the Sun is a solid object that is also a source of light, and therefore it cannot cause a shadow unless the light source the Sun is in the way of is brighter than the Sun itself.  

There are celestial bodies, such as the star Sirius, that is brighter than the Sun, but it is too far away from the Sun to affect it or cause the Sun to have a shadow.  

What Does Shadows in Space Mean for NASA? 

Shadows are very useful to the scientists at NASA because shadows could be signs of heavenly bodies that cannot be seen. Between 2015 and 2016, the Hubble Space Telescope at NASA detected a rotating shadow while researching a young star TW Hydrae.  

This rotating shadow is believed to be a hidden planet approximately the size of Jupiter.  

The discovery of the planet is a recent discovery, but it is not the first and not the last discovery because of shadows cast by surrounding heavenly bodies. New starts and moons are regularly discovered in this manner, and it is instrumental when the findings are too far into space to be seen clearly by our technology.  

Photometry is a method used by NASA to measure the brightness of a star.  When the star’s brightness is decreased over a length of time, it is believed to be a solar eclipse of the star because a planet is casting a shadow on the start.  

By using this method, NASA can discover planets that exist outside our solar system.  These planets are called Exoplanets.  The method of Photometry is using shadows to predict the existence of new worlds beyond our solar system.  

Conclusion

Shadows are created when light passes through a solid body.  This body does not allow the light to pass through, and a shadow is formed.  The only thing that can make a shadow is a source of light; it is, therefore, impossible for shadows to be made by a solid body like a planet.  

The earth casts a shadow on itself, called night, and on the space around it.  The shadow cast on the moon causes the phases of the moon.  The earth’s shadow also causes solar and lunar eclipses and is responsible for the red moon known as the blood moon.  

Venus is a planet that appears bright because its thick cloud cover causes it to reflect the Sun’s light.  This planet seems so bright that it can cause shadows to form. However, these shadows lack the Penumbra that regular shadows have and are not actual shadows.  

The Sun is a source of light and can only cast a shadow if it comes in the path of a more powerful source of light.  There are celestial bodies brighter than the Sun, but it is too far from the Sun to allow the Sun to cast a shadow.  

Shadows are very useful to scientists a NASA.   Shadows that pass over a star can prove the existence of a new planet outside our solar system.  These planets are called Exoplanets.

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